UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

(Rule 13d-101)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO § 240.13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO

§ 240.13d-2(a)

(Amendment No. 1)¹

Aviragen Therapeutics, Inc.

(Name of Issuer)

Common Stock, par value $0.10 per share

(Title of Class of Securities)

053761102

(CUSIP Number)

(Name, Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

January 11, 2018

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box ¨.

Note:  Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits.  See § 240.13d-7 for other parties to whom copies are to be sent.

1              The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

¹ Based on 38,649,237 shares of common stock of the Issuer outstanding as of November 3, 2017, as reported in the Issuer’s Form 10-Q for the quarter ended September 30, 2017, filed with the SEC on November 7, 2017.

² Based on 38,649,237 shares of common stock of the Issuer outstanding as of November 3, 2017, as reported in the Issuer’s Form 10-Q for the quarter ended September 30, 2017, filed with the SEC on November 7, 2017.

³ Based on 38,649,237 shares of common stock of the Issuer outstanding as of November 3, 2017, as reported in the Issuer’s Form 10-Q for the quarter ended September 30, 2017, filed with the SEC on November 7, 2017.

The following constitutes Amendment No. 1 to the Schedule 13D filed by the undersigned (the “Amendment No. 1”). This Amendment No. 1 amends the Schedule 13D as specifically set forth herein.

Item 2 is hereby amended and restated to read as follows:

(a)       This statement is filed by:

Each of the foregoing is referred to as a “Reporting Person” and collectively as the “Reporting Persons.” Each of the Reporting Persons is party to that certain Joint Filing and Solicitation Agreement, as further described in Item 6. Accordingly, the Reporting Persons are hereby filing a joint Schedule 13D.

EHM is the investment manager of East Hill Hedge Fund, LLC, a Delaware limited liability company (“EHHF”) and the EHM Managed Accounts, each of which directly owns Shares. Mr. Thomas M. Clay is the sole Manager of EHM. Each of EHHF and the EHM Managed Accounts has delegated to EHM the sole authority to vote and dispose of the securities held by them pursuant to an Investment Management Agreement. As a result, each of EHM and Thomas M. Clay may be deemed to beneficially own the Shares held by each of EHHF and the EHM Managed Accounts. Thomas M. Clay is a Trustee of the Landon T. Clay 2009 Revocable Trust (the “LTC Trust”), which directly owns Shares. As Trustee, Mr. Thomas M. Clay has been delegated sole authority to vote and dispose of the securities held in the LTC Trust. As a result, Mr. Thomas M. Clay may be deemed to beneficially own the Shares held by the LTC Trust.

(b)       The address of the principal office of Digirad is 1048 Industrial Court, Suwanee, Georgia 30024. The principal business address of EHM and Mr. Thomas M. Clay is c/o East Hill Management Company, LLC, 70 Main Street, Suite 300, Peterborough, New Hampshire 03458. The principal business address of Mr. Broenniman is c/o Varana Capital, LLC, 81 Prospect Street, Brooklyn, New York 11201. The principal business address of Mr. Elbaor is 222 W. Merchandise Mart Plaza #1212, Chicago, Illinois 60654. The principal business address of Mr. Evans is 633 N. Ironwood Dr., Arlington Heights, Illinois 60004. The principal business address of Mr. Gardner is c/o Varana Capital, LLC, 81 Prospect Street, Brooklyn, New York 11201. The principal business address of Mr. Halas is 38 Pheasant Run Place, Danville, California 94506. The principal business address of Mr. Harper is 6680 Gunpark Drive, Suite 202B, Boulder, Colorado 80301. The principal business address of Mr. Keddie is 8719 258^th Avenue NE, Redmond, Washington 98053. The principal business address of Mr. Keyes is c/o Digirad Corporation, 1048 Industrial Court, Suwanee, Georgia 30024. The principal business address of Mr. Kravetz is One International Place, 14^th Floor, Boston, Massachusetts 02110. The principal business address of Mr. Large is 304 S. Jones Blvd #3367, Las Vegas NV 89107. The principal business address of Mr. Nelson is c/o Invenire Capital, LLC, 90 Grove Street, Suite 206, Ridgefield, Connecticut 06877. The officers and directors of Digirad, and their principal occupations and business addresses are set forth on Schedule A and are incorporated by reference in this Item 2.

(c)       The principal business of Digirad is providing mobile healthcare solutions and medical equipment and services, including diagnostic imaging and patient monitoring, to hospitals, physician practices, and imaging centers throughout the U.S. The principal business of EHM is as a registered investment advisory firm which acts as investment manager to EHHF and the EHM Managed Accounts. The principal occupation of Mr. Thomas M. Clay is as a Vice President and sole Manager of EHM. Mr. Thomas M. Clay is also a Trustee of the LTC Trust, the President of LTC Corporation and a director and the chief executive officer of Golden Queen Mining Co. Ltd. (Toronto Stock Exchange: GQM), and chairman of ThromboGenics, NV (Euronext: THR). The principal occupation of Mr. Broenniman is as Portfolio Manager and Managing Partner for Varana Capital, LLC. The principal occupation of Mr. Elbaor is as a consulting advisor to Lucus Advisors LLC. The principal occupation of Mr. Evans is as the Interim Chief Executive Officer of Hill International, Inc. The principal occupation of Mr. Gardner is as Partner and Co-Founder of Varana Capital, LLC. The principal occupation of Mr. Halas is as a consultant to Central Garden & Pet Company, various private equity groups and a number of hedge funds. The principal occupation of Mr. Harper is as the founder and president of Harper Asset Management, LLC. The principal occupation of Mr. Keddie is as President & CEO of Value Creation Management Group LLC. The principal occupation of Mr. Keyes is as Chief Financial Officer and Corporate Secretary of Digirad. The principal occupatoin of Mr. Kravetz is as President and Chief Investment Officer of Esplanade Capital LLC. The principal occupation of Mr. Large is as the Managing Partner at Nutmeg Investments LLC. The principal occupation of Mr. Nelson is as the Managing Partner of Invenire Capital, LLC.

(d)       No Reporting Person, nor any person listed on Schedule A, annexed hereto, has, during the last five years, been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).

(e)       Except as otherwise set forth on Schedule A, annexed hereto, no Reporting Person, nor any person listed on Schedule A, has, during the last five years, been party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

(f)       Messrs. Clay, Broenniman, Elbaor, Evans, Gardner, Halas, Harper, Keyes, Kravetz, Large and Nelson is a citizen of the United States of America. Mr. Evans is also a citizen of Britain. Mr. Gardner is also a citizen of Israel. Mr. Keddie is a citizen of Canada. The citizenship of the persons listed on Schedule A is set forth therein.

Item 4 is hereby amended to add the following:

On January 11, 2018, Digirad, on behalf of itself, EHM and Thomas M. Clay, delivered a letter to the Issuer nominating Philip R. Broenniman, James C. Elbaor, Paul J. Evans, Ezra M. Gardner, Gus D. Halas, Brian J. Harper, Lee D. Keddie, Jeffry R. Keyes, Shawn W. Kravetz, Benjamin E. Large and Chad M. Nelson (the “Nominees”) to the Board of Directors of the Issuer (the “Board”) at the next annual meeting of stockholders (the “Annual Meeting”).

On January 12, 2018, Digirad, on behalf of itself, EHM and Thomas M. Clay, filed a preliminary proxy statement with the SEC in connection with the Special Meeting of stockholders of the Issuer with respect to the proposed Merger between the Issuer and Vaxart Inc.

Item 5(a)-(c) is hereby amended and restated to read as follows:

The aggregate percentage of Shares reported owned by each person named herein is based upon 38,649,237 Shares outstanding as of November 3, 2017, which is the total number of Shares outstanding as reported in the Issuer’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on November 7, 2017.

Percentage: Less than 1%

Percentage: Approximately 7.5%

Percentage: Approximately 8.3%

Percentage: 0%

The Reporting Persons, as members of a “group” for the purposes of Section 13(d)(3) of the Securities Exchange Act of 1934, as amended, may be deemed the beneficial owner of the Shares directly owned by the other Reporting Persons. As of the close of business on January 12, 2018, the aggregate beneficial ownership by the members of the group was 3,196,106 Shares, or approximately 8.3% of the outstanding Shares. Each Reporting Person disclaims beneficial ownership of such Shares except to the extent of his or its pecuniary interest therein.

Item 6 is hereby amended to add the following:

On January 11, 2018, the Reporting Persons entered into an Amended and Restated Joint Filing and Solicitation Agreement (the “Joint Filing and Solicitation Agreement”), in which, among other things, the Reporting Persons agreed to (a) the joint filing on behalf of each of them of statements on Schedule 13D, and any amendments thereto, with respect to the securities of the Issuer and (b) form a group (collectively, the “Concerned Aviragen Shareholders Group” or “CAS Group”) for the purposes of (i) seeking representation on the Board of Directors of the Issuer (the “Board”) at the next meeting of stockholders of the Issuer at which directors can be elected, (ii) for soliciting stockholder support for director nominations and any other proposal submitted by the CAS Group and (iii) for such other actions as the members of the CAS Group agree to take, including, but not limited to, soliciting stockholder support against the proposed merger between the Issuer and Vaxart, Inc., and for the purpose of taking all other action necessary to achieve the foregoing. Pursuant to the Joint Filing and Solicitation Agreement, the Reporting Persons agreed that (a) any director candidates to be nominated to the Board by the CAS Group shall be selected by mutual agreement, (ii) all strategic decisions regarding the actions taking by the CAS Group shall be decided by mutual agreement and (iii) Digirad alone shall have the right to pre-approve all expenses incurred in connection with the CAS Group’s activities and agrees to pay directly all such pre-approved expenses. Under the Joint Filing and Solicitation Agreement, East Hill agreed that it will not, and it will cause its affiliates not to, sell to the Issuer any shares of the Issuer beneficially owned by East Hill or its affiliates unless (i) East Hill reasonably believes that any large shareholder (beneficial owner of at least 3% of the outstanding shares) of the Issuer intends to sell, or has sold, any shares of the Issuer to the Issuer at a premium over the then current trading price of the shares of the Issuer, or (ii) East Hill reasonably believes that the CAS Group will be unsuccessful in its efforts to elect directors to the Board. In addition, the Reporting Persons agreed that if the CAS Group is successful in its nomination of directors to the Board, the CAS Group will seek reimbursement for (i) East Hill’s legal expenses relating to its previous efforts to effect change at the Issuer and (ii) the CAS Group’s and Digirad’s legal expenses relating to the CAS Group’s activities. The Joint Filing and Solicitation Agreement entered into on January 11, 2018 is substantially the same as the Joint Filing and Solicitation Agreement entered into by the Reporting Persons on December 29, 2017. The foregoing description of the Joint Filing and Solicitation Agreement is qualified in its entirety by reference to the Joint Filing and Solicitation Agreement, which is attached as Exhibit 99.1 hereto and is incorporated herein by reference.

On January 11, 2018, each of the Nominees entered into a Joinder Agreement (the “Joinder Agreement”) to that certain Joint Filing and Solicitation Agreement, dated January 11, 2018, pursuant to which the Nominees agreed to be bound by the terms and conditions set forth therein, including, among other things, the joint filing on behalf of each party of statements on Schedule 13D, and any amendments thereto, with respect to the securities of the Issuer. The foregoing description of the Joinder Agreement is qualified in its entirety by reference to the Joinder Agreement, which is attached hereto as Exhibit 99.2 and is incorporated herein by reference.

Pursuant to letter agreements, Digirad has agreed to indemnify each of the Nominees against claims arising from the Solicitation and any related transactions.  A form of the indemnification letter agreement is attached hereto as Exhibit 99.3 and is incorporated herein by reference.

Item 7 is hereby amended to add the following exhibits:

SIGNATURES

After reasonable inquiry and to the best of his or its knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

Dated: January 16, 2018

SCHEDULE A

Directors and Officers of Digirad Corporation

Lone Star Value Management, LLC, Mr. Eberwein and Mr. Gillman are each subject to a Securities and Exchange Commission (“SEC”) administrative order, dated February 14, 2017 (Securities Exchange Act Release No. 80038), relating to alleged violations of Section 13(d) of the Securities Exchange Act of 1934 (the “Exchange Act”) and the rules promulgated thereunder, including failing to disclose the members of a stockholder group, and further allegations that Messrs. Eberwein and Gillman violated Section 16(a) of the Exchange Act and the rules promulgated thereunder, including failing to timely file initial statements of beneficial ownership on Form 3 and changes thereto on Form 4. Without admitting or denying any violations, (i) Lone Star Value Management agreed to cease and desist from committing or causing any violations of Section 13(d) of the Exchange Act and Rules 13d-1 and 13d-2 promulgated thereunder, and paid a civil penalty of $120,000 to the SEC and (ii) Messrs. Eberwein and Gillman agreed to cease and desist from committing or causing any violations of (x) Section 13(d) of the Exchange Act and Rules 13d-1 and 13d-2 promulgated thereunder and (y) Section 16(a) of the Exchange Act and Rules 16a-2 and 16a-3 promulgated thereunder, and each paid a civil penalty to the SEC in the respective amounts of $90,000 and $30,000.

Exhibit 99.1

AMENDED AND RESTATED JOINT FILING AND SOLICITATION AGREEMENT

WHEREAS, certain of the parties hereto are stockholders, direct or beneficial, of Aviragen Therapeutics, Inc., a Delaware corporation (the “Company”);

WHEREAS, Digirad Corporation, a Delaware corporation (“Digirad”), East Hill Management Company, LLC, a Delaware limited liability company (“East Hill Management”) and Thomas M. Clay (collectively with East Hill Management, “East Hill”) and any person added as a party to this Joint Filing and Solicitation Agreement (this “Agreement”) wish to form a group for the purpose of seeking representation on the Board of Directors of the Company (the “Board”) at the next meeting of stockholders of the Company at which directors can be elected (including any other meeting of stockholders held in lieu thereof, and any adjournments, postponements, reschedulings or continuations thereof, the “Meeting”), for soliciting stockholder support for director nominations and any other proposal submitted by the CAS Group (as defined below), for such other actions as the members of the CAS Group agree to take, including, but not limited to, soliciting stockholder support against the proposed merger between the Company and Vaxart, Inc., and for the purpose of taking all other action necessary to achieve the foregoing.

NOW, IT IS AGREED, this 11th day of January 2018 by the parties hereto:

1.       In accordance with Rule 13d-1(k)(1)(iii) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), each of Digirad and East Hill and each person added as a party to this Agreement (collectively, the “Concerned Aviragen Shareholders Group” or “CAS Group”) agrees to the joint filing on behalf of each of them of statements on Schedule 13D, and any amendments thereto, with respect to the securities of the Company, provided such filings are made in accordance with this Agreement. Each member of the CAS Group shall be responsible for the accuracy and completeness of his/its own disclosure therein, and is not responsible for the accuracy and completeness of the information concerning the other members, unless such member knows or has reason to know that such information is inaccurate.

2.       So long as this agreement is in effect, Digirad, on the one hand and East Hill, on the other hand, shall provide written notice to the other party of, and Digirad, East Hill and any person who is added as a party to this Agreement shall provide written notice to Olshan Frome Wolosky LLP (“Olshan”), of (i) any of its purchases or sales of securities of the Company; or (ii) any securities of the Company over which it acquires or disposes of beneficial ownership. Such notice shall be provided within 24 hours of each transaction.

3.       Each party hereto agrees that (i) any director candidates to be nominated to the Board by the CAS Group shall be selected by mutual agreement of Digirad and East Hill, (ii) all strategic decisions regarding the actions taking by the CAS Group shall be decided by mutual agreement of Digirad and East Hill, and (iii) Digirad alone shall have the right to pre-approve all expenses incurred in connection with the CAS Group’s activities hereunder and Digirad agrees to pay directly all such pre-approved expenses, including but not limited to Olshan’s fees and expenses.

4.       Each party hereto agrees that (a) any SEC filing, press release or stockholder communication required or proposed to be made or issued by the CAS Group or any member of the CAS Group in connection with the CAS Group’s activities shall be first approved by both Digirad and East Hill, or their representatives, which approval shall not be unreasonably withheld, and (b) any calls or meetings with, or other communications between, any member of the CAS Group or its representatives, on the one hand, and the Company or any other shareholder of the Company (or their respective representatives), on the other hand, shall not be made or held unless a representative of each member of the CAS Group participates in such call, meeting or other communication.

5.       East Hill agrees that it will not, and it will cause its affiliates not to, sell to the Company any shares of the Company beneficially owned by East Hill or its affiliates unless (i) East Hill reasonably believes that any large shareholder of the Company intends to sell, or has sold, any of such large shareholder’s shares of the Company to the Company at a premium over the then current trading price of the shares of the Company, or (ii) East Hill reasonably believes that the CAS Group will be unsuccessful in its efforts to elect directors to the Board. For the purposes of this Agreement, (a) a “large shareholder” is any shareholder who at any point during the term of this Agreement beneficially owns at least 3% of the outstanding shares of the Company, and (b) “affiliate” of East Hill means an affiliate of East Hill over whom East Hill has control.

6.       The relationship of the parties hereto shall be limited to carrying out the purposes of the CAS Group in accordance with the terms of this Agreement. Such relationship shall be construed and deemed to be for the sole and limited purpose of carrying out such purposes as described herein. Nothing herein shall be construed to authorize any party to act as an agent for any other party, or to create a joint venture or partnership, or to constitute an indemnification. Except as provided in Section 5 above, nothing herein shall restrict any party’s right to purchase or sell securities of the Company, as he/it deems appropriate, in his/its sole discretion, provided that all such sales are made in compliance with all applicable securities laws.

7.       This Agreement may be executed in counterparts, each of which shall be deemed an original and all of which, taken together, shall constitute but one and the same instrument, which may be sufficiently evidenced by one counterpart.

8.       In the event of any dispute arising out of the provisions of this Agreement or the parties’ investment in the Company, the parties hereto consent and submit to the nonexclusive jurisdiction of the Supreme Court of the State of New York sitting in New York County and of the United States District Court for the Southern District of New York, and any appellate court from any thereof. This Agreement is a contract under the laws of the State of New York and shall for all purposes be construed in accordance with and governed by the laws of said State without reference to its conflict or choice of laws principles (other than Sections 5-1401 and 5-1402 of the New York General Obligations Law, which shall apply to this Agreement).

9.       The parties’ rights and obligations under this agreement (other than the rights and obligations set forth in Section 3 and Section 8 which shall survive any termination of this agreement) shall terminate immediately after the conclusion of the activities for which the CAS Group was formed, including upon entry into any settlement agreement with the Company, or as otherwise agreed to by the parties.  Notwithstanding the foregoing, any party hereto may terminate his/its obligations under this agreement on 24 hours’ written notice to all other parties, with a copy by fax to Adam W. Finerman at Olshan, Fax No. (212) 451-2222.

10.       All notices, requests and demands to or upon the respective parties hereto to be effective shall be in writing (including by facsimile or .pdf), and, unless otherwise expressly provided herein, shall be deemed to have been duly given or made (a) when delivered by hand, (b) when transmitted via facsimile to the number set out herein, (c) when delivered by electronic mail, when delivered, or (d) the second Business Day following the day on which the same has been delivered prepaid to a reputable national express air courier service, addressed as follows, or to such other address as may be hereafter notified by the respective parties hereto:

If to Digirad:

Digirad Corporation

1048 Industrial Court

Suwanee, GA 30024

Attention: Jeffrey R. Keyes

Facsimile: (858) 726-1546

Email: jeffry.keyes@digirad.com

with a copy to (which shall not constitute notice):

Olshan Frome Wolosky LLP

1325 Avenue of the Americas

New York, New York 10019

Attention: Adam W. Finerman, Esq. and Timothy D. Knox, Esq.

Facsimile: (212) 451-2222

Email: afinerman@olshanlaw.com, tknox@olshanlaw.com

If to East Hill:

East Hill Management Company, LLC

70 Main Street

Suite 300

Petersborough, NH 03458

Attention: Thomas M. Clay

Facsimile: (603) 371-9034

Email: thomas.clay@easthillmgt.com

with a copy to (which shall not constitute notice):

Sullivan & Worcester LLP

One Post Office Square

Boston, MA 02109

Attention: William A. Levine, Esq. and Benjamin J. Armour

Facsimile: (617) 338-2880

E-mail: wlevine@sandw.com, barmour@sandw.com

11.       Each party acknowledges that Olshan shall act as counsel for both the CAS Group and Digirad and its affiliates relating to their investment in the Company and each party agrees that Olshan will prepare, file and/or issue all SEC and other regulatory filings, press releases or stockholder communications proposed to be made or issued by the CAS Group in connection with the actions of the CAS Group with respect to the Company and approved as provided in this Agreement, unless otherwise agreed by the parties. The parties agree that if the CAS Group is successful in its nomination of directors to the Board, the CAS Group will seek reimbursement for (i) East Hill’s legal expenses relating to its previous efforts to effect change at the Company prior to the date hereof and (ii) the CAS Group’s and Digirad’s legal expenses relating to the CAS Group’s activities.

12.       The terms and provisions of this Agreement may not be modified, waived or amended without the written consent of each of the parties hereto. 

13.       Each party hereto hereby agrees that this Agreement shall be filed as an exhibit to a Schedule 13D pursuant to Rule 13d-1(k)(1)(iii) under the Exchange Act.

[Signature pages follow]

IN WITNESS WHEREOF, the parties hereto have caused this Joint Filing and Solicitation Agreement to be executed as of the day and year first above written.

Signature Page to A&R Joint Filing and Solicitation Agreement

Exhibit 99.2

JOINDER AGREEMENT

This JOINDER AGREEMENT (the “Joinder”) is dated as of January 11, 2018 by and among Digirad Corporation, a Delaware corporation, East Hill Management Company, LLC, a Delaware limited liability company and Thomas M. Clay (collectively, the “Existing Members”) and Philip R. Broenniman, James C. Elbaor, Paul J. Evans, Ezra M. Gardner, Brian J. Harper, Gus D. Halas, Lee D. Keddie, Jeffry R. Keyes, Shawn W. Kravetz, Benjamin E. Large and Chad M. Nelson (the “New Members”). Capitalized terms not defined herein shall have the meanings set forth in the Agreement (as defined below).

WHEREAS, the Existing Members are parties to that certain Amended and Restated Joint Filing and Solicitation Agreement dated as of January 11, 2018 (the “Agreement”), pursuant to which the Existing Members formed a “group” (as contemplated by Section 13(d) of the Securities Exchange Act of 1934, as amended) for the purposes of seeking representation on the Board of Directors (the “Board”) of Aviragen Therapeutics, Inc. (the “Company”) at the next meeting of stockholders of the Company at which directors can be elected (including any other meeting of stockholders held in lieu thereof, and any adjournments, postponements, reschedulings or continuations thereof, the “Meeting”), for soliciting stockholder support for director nominations and any other proposal submitted by the CAS Group, for such other actions as the members of the CAS Group agree to take, including, but not limited to, soliciting stockholder support against the proposed merger between the Company and Vaxart, Inc., and for the purpose of taking all other action necessary to achieve the foregoing; and

WHEREAS, the New Members desire to join the group formed by the Existing Members.

NOW, THEREFORE, in consideration of the premises and of the mutual covenants and agreements of the parties herein contained, the parties hereby agree as follows:

1.       Effective immediately, the New Members are joined as a party to the Agreement.

2.       The New Members agree to be bound by the terms of the Agreement, the terms of which are incorporated herein and made a part hereof.

3.       This Joinder may be executed in counterparts, each of which shall be deemed an original and all of which, taken together, shall constitute but one and the same instrument, which may be sufficiently evidenced by one counterpart.

[Signature page on next page] 

IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be executed as of the day and year first above written. 

Signature Page to Joinder Agreement

Signature Page to Joinder Agreement

Exhibit 99.3

DIGIRAD CORPORATION

1048 Industrial Court

Suwanee, GA 30024

January ____, 2018

Name of Nominee:

Address of Nominee:

Re: Aviragen Therapeutics, Inc.

Dear ____________:

Thank you for agreeing to serve as a nominee for election to the Board of Directors of Aviragen Therapeutics, Inc. (the “Company”) in connection with the proxy solicitation that Digirad Corporation (“DRAD”), together with East Hill Management Company, LLC and Thomas M. Clay, or any of their affiliates (collectively, the “Group”) is considering undertaking to approve certain business proposals and to nominate and elect directors at the Company’s next annual meeting of stockholders of the Company, including any other meeting of stockholders held in lieu thereof, and any adjournments, postponements, reschedulings or continuations thereof and to take such other actions as the members of the Group agree to take, including, but not limited to, soliciting stockholder support against the proposed merger between the Company and Vaxart, Inc. (collectively, the “Solicitation”). Your outstanding qualifications, we believe, will prove a valuable asset to the Company and all of its stockholders. This letter (this “Agreement”) will set forth the terms of our agreement.

DRAD agrees to jointly and severally indemnify and hold you harmless against any and all claims of any nature, whenever brought, arising from the Solicitation and any related transactions, irrespective of the outcome; provided, however, that you will not be entitled to indemnification for claims arising from your gross negligence, willful misconduct, intentional and material violations of law, criminal actions or material breach of the terms of this agreement; provided further, that upon your becoming a director of the Company, this indemnification shall not apply to any claims made against you in your capacity as a director of the Company. This indemnification will include any and all losses, liabilities, damages, demands, claims, suits, actions, judgments, or causes of action, assessments, costs and expenses, including, without limitation, interest, penalties, reasonable attorneys’ fees, and any and all reasonable costs and expenses incurred in investigating, preparing or defending against any litigation, commenced or threatened, any civil, criminal, administrative or arbitration action, or any claim whatsoever, and any and all amounts paid in settlement of any claim or litigation asserted against, resulting, imposed upon, or incurred or suffered by you, directly or indirectly, as a result of or arising from the Solicitation and any related transactions (each, a “Loss”).

In the event of a claim against you pursuant to the prior paragraph or the occurrence of a Loss, you shall give DRAD prompt written notice of such claim or Loss (provided that failure to promptly notify DRAD shall not relieve us from any liability which we may have on account of this Agreement, except to the extent we shall have been materially prejudiced by such failure). Upon receipt of such written notice, DRAD will provide you with counsel to represent you. Such counsel shall be reasonably acceptable to you. In addition, you will be reimbursed promptly for all Losses suffered by you and as incurred as provided herein. DRAD may not enter into any settlement of loss or claim without your consent unless such settlement includes a release of you from any and all liability in respect of such claim.

You hereby agree to keep confidential and not disclose to any party, without the consent of DRAD, any confidential, proprietary or non-public information (collectively, “Information”) of DRAD, its affiliates or members of its Schedule 13D group which you have heretofore obtained or may obtain in connection with your service as a nominee hereunder. Notwithstanding the foregoing, Information shall not include any information that is publicly disclosed by DRAD, its affiliates or members of its Schedule 13D group or any information that you can demonstrate is now, or hereafter becomes, through no act or failure to act on your part, otherwise generally known to the public.

Notwithstanding the foregoing, if you are required by applicable law, rule, regulation or legal process to disclose any Information you may do so provided that you first promptly notify DRAD so that DRAD or any member thereof may seek a protective order or other appropriate remedy or, in DRAD’s sole discretion, waive compliance with the terms of this Agreement. In the event that no such protective order or other remedy is obtained or DRAD does not waive compliance with the terms of this Agreement, you may consult with counsel at the cost of DRAD and you may furnish only that portion of the Information which you are advised by counsel is legally required to be so disclosed and you will request that the party(ies) receiving such Information maintain it as confidential.

All Information, all copies thereof, and any studies, notes, records, analysis, compilations or other documents prepared by you containing such Information, shall be and remain the property of DRAD and, upon the request of a representative of DRAD, all such information shall be returned or, at DRAD’s option, destroyed by you, with such destruction confirmed by you to DRAD in writing.

This letter agreement shall be governed by the laws of the State of New York, without regard to the principles of the conflicts of laws thereof.

* * *

If you agree to the foregoing terms, please sign below to indicate your acceptance.

Very truly yours,

ACCEPTED AND AGREED:

________________________

Exhibit 99.4

POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby constitutes and appoints Jeffry R. Keyes and Thomas M. Clay or either of them as the undersigned’s true and lawful attorney-in-fact to take any and all action in connection with (i) the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of Aviragen Therapeutics, Inc. (the “Company”) directly or indirectly beneficially owned by Digirad Corporation, East Hill Management Company, LLC, Thomas M. Clay, or any of their affiliates or other persons added as members of the group (collectively, the “Group”) and (ii) any proxy solicitation of the Group (a) to elect the Group’s slate of director nominees to the board of directors of the Company and approve any proposals submitted by the Group at the next meeting of stockholders of the Company at which directors are elected and (b) for such other actions as the members of the CAS Group agree to take, including, but not limited to, soliciting stockholder support against the proposed merger between the Company and Vaxart, Inc., and for the purpose of taking all other action necessary to achieve the foregoing (collectively, the “Solicitation”). Such action shall include, but not be limited to:

1.       executing for and on behalf of the undersigned any Schedule 13D, and amendments thereto, filed by the Group that are required to be filed under Section 13(d) of the Securities Exchange Act of 1934 (the “Exchange Act”) and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

2.       executing for and on behalf of the undersigned all Forms 3, 4 and 5 required to be filed under Section 16(a) of the Securities Exchange Act of 1934 and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

3.       executing for and on behalf of the undersigned all Joint Filing and Solicitation Agreements or similar documents pursuant to which the undersigned shall agree to be a member of the Group;

4.       performing any and all acts for and on behalf of the undersigned that may be necessary or desirable to complete and execute any such document, complete and execute any amendment or amendments thereto, and timely file such form with the United States Securities and Exchange Commission and any stock exchange or similar authority; and

5.       taking any other action of any type whatsoever in connection with the Solicitation, including entering into any settlement agreement, that in the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required by, the undersigned, it being understood that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to this Power of Attorney shall be in such form and shall contain such terms and conditions as such attorney-in-fact may approve in such attorney-in-fact's discretion.

The undersigned hereby grants to such attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact’s substitutes, shall lawfully do or cause to be done by virtue of this Power of Attorney and the rights and powers herein granted. The undersigned acknowledges that each of the foregoing attorneys-in-fact, in serving in such capacity at the request of the undersigned, is not assuming any of the undersigned's responsibilities to comply with Section 13(d), Section 16 or Section 14 of the Exchange Act.

This Power of Attorney shall remain in full force and effect until the undersigned is no longer a member of the Group unless earlier revoked by the undersigned in a signed writing delivered to the foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed as of this 11th day of January 2018.

/s/ PHILIP R. BROENNIMAN

Philip R. Broenniman

POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby constitutes and appoints Jeffry R. Keyes and Thomas M. Clay or either of them as the undersigned’s true and lawful attorney-in-fact to take any and all action in connection with (i) the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of Aviragen Therapeutics, Inc. (the “Company”) directly or indirectly beneficially owned by Digirad Corporation, East Hill Management Company, LLC, Thomas M. Clay, or any of their affiliates or other persons added as members of the group (collectively, the “Group”) and (ii) any proxy solicitation of the Group (a) to elect the Group’s slate of director nominees to the board of directors of the Company and approve any proposals submitted by the Group at the next meeting of stockholders of the Company at which directors are elected and (b) for such other actions as the members of the CAS Group agree to take, including, but not limited to, soliciting stockholder support against the proposed merger between the Company and Vaxart, Inc., and for the purpose of taking all other action necessary to achieve the foregoing (collectively, the “Solicitation”). Such action shall include, but not be limited to:

1.       executing for and on behalf of the undersigned any Schedule 13D, and amendments thereto, filed by the Group that are required to be filed under Section 13(d) of the Securities Exchange Act of 1934 (the “Exchange Act”) and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

2.       executing for and on behalf of the undersigned all Forms 3, 4 and 5 required to be filed under Section 16(a) of the Securities Exchange Act of 1934 and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

3.       executing for and on behalf of the undersigned all Joint Filing and Solicitation Agreements or similar documents pursuant to which the undersigned shall agree to be a member of the Group;

4.       performing any and all acts for and on behalf of the undersigned that may be necessary or desirable to complete and execute any such document, complete and execute any amendment or amendments thereto, and timely file such form with the United States Securities and Exchange Commission and any stock exchange or similar authority; and

5.       taking any other action of any type whatsoever in connection with the Solicitation, including entering into any settlement agreement, that in the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required by, the undersigned, it being understood that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to this Power of Attorney shall be in such form and shall contain such terms and conditions as such attorney-in-fact may approve in such attorney-in-fact's discretion.

The undersigned hereby grants to such attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact’s substitutes, shall lawfully do or cause to be done by virtue of this Power of Attorney and the rights and powers herein granted. The undersigned acknowledges that each of the foregoing attorneys-in-fact, in serving in such capacity at the request of the undersigned, is not assuming any of the undersigned's responsibilities to comply with Section 13(d), Section 16 or Section 14 of the Exchange Act.

This Power of Attorney shall remain in full force and effect until the undersigned is no longer a member of the Group unless earlier revoked by the undersigned in a signed writing delivered to the foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed as of this 11th day of January 2018.

/s/ JAMES C. ELBAOR

James C. Elbaor

POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby constitutes and appoints Jeffry R. Keyes and Thomas M. Clay or either of them as the undersigned’s true and lawful attorney-in-fact to take any and all action in connection with (i) the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of Aviragen Therapeutics, Inc. (the “Company”) directly or indirectly beneficially owned by Digirad Corporation, East Hill Management Company, LLC, Thomas M. Clay, or any of their affiliates or other persons added as members of the group (collectively, the “Group”) and (ii) any proxy solicitation of the Group (a) to elect the Group’s slate of director nominees to the board of directors of the Company and approve any proposals submitted by the Group at the next meeting of stockholders of the Company at which directors are elected and (b) for such other actions as the members of the CAS Group agree to take, including, but not limited to, soliciting stockholder support against the proposed merger between the Company and Vaxart, Inc., and for the purpose of taking all other action necessary to achieve the foregoing (collectively, the “Solicitation”). Such action shall include, but not be limited to:

1.       executing for and on behalf of the undersigned any Schedule 13D, and amendments thereto, filed by the Group that are required to be filed under Section 13(d) of the Securities Exchange Act of 1934 (the “Exchange Act”) and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

2.       executing for and on behalf of the undersigned all Forms 3, 4 and 5 required to be filed under Section 16(a) of the Securities Exchange Act of 1934 and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

3.       executing for and on behalf of the undersigned all Joint Filing and Solicitation Agreements or similar documents pursuant to which the undersigned shall agree to be a member of the Group;

4.       performing any and all acts for and on behalf of the undersigned that may be necessary or desirable to complete and execute any such document, complete and execute any amendment or amendments thereto, and timely file such form with the United States Securities and Exchange Commission and any stock exchange or similar authority; and

5.       taking any other action of any type whatsoever in connection with the Solicitation, including entering into any settlement agreement, that in the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required by, the undersigned, it being understood that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to this Power of Attorney shall be in such form and shall contain such terms and conditions as such attorney-in-fact may approve in such attorney-in-fact's discretion.

The undersigned hereby grants to such attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact’s substitutes, shall lawfully do or cause to be done by virtue of this Power of Attorney and the rights and powers herein granted. The undersigned acknowledges that each of the foregoing attorneys-in-fact, in serving in such capacity at the request of the undersigned, is not assuming any of the undersigned's responsibilities to comply with Section 13(d), Section 16 or Section 14 of the Exchange Act.

This Power of Attorney shall remain in full force and effect until the undersigned is no longer a member of the Group unless earlier revoked by the undersigned in a signed writing delivered to the foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed as of this 11th day of January 2018.

/s/ PAUL J. EVANS

Paul J. Evans

POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby constitutes and appoints Jeffry R. Keyes and Thomas M. Clay or either of them as the undersigned’s true and lawful attorney-in-fact to take any and all action in connection with (i) the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of Aviragen Therapeutics, Inc. (the “Company”) directly or indirectly beneficially owned by Digirad Corporation, East Hill Management Company, LLC, Thomas M. Clay, or any of their affiliates or other persons added as members of the group (collectively, the “Group”) and (ii) any proxy solicitation of the Group (a) to elect the Group’s slate of director nominees to the board of directors of the Company and approve any proposals submitted by the Group at the next meeting of stockholders of the Company at which directors are elected and (b) for such other actions as the members of the CAS Group agree to take, including, but not limited to, soliciting stockholder support against the proposed merger between the Company and Vaxart, Inc., and for the purpose of taking all other action necessary to achieve the foregoing (collectively, the “Solicitation”). Such action shall include, but not be limited to:

1.       executing for and on behalf of the undersigned any Schedule 13D, and amendments thereto, filed by the Group that are required to be filed under Section 13(d) of the Securities Exchange Act of 1934 (the “Exchange Act”) and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

2.       executing for and on behalf of the undersigned all Forms 3, 4 and 5 required to be filed under Section 16(a) of the Securities Exchange Act of 1934 and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

3.       executing for and on behalf of the undersigned all Joint Filing and Solicitation Agreements or similar documents pursuant to which the undersigned shall agree to be a member of the Group;

4.       performing any and all acts for and on behalf of the undersigned that may be necessary or desirable to complete and execute any such document, complete and execute any amendment or amendments thereto, and timely file such form with the United States Securities and Exchange Commission and any stock exchange or similar authority; and

5.       taking any other action of any type whatsoever in connection with the Solicitation, including entering into any settlement agreement, that in the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required by, the undersigned, it being understood that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to this Power of Attorney shall be in such form and shall contain such terms and conditions as such attorney-in-fact may approve in such attorney-in-fact's discretion.

The undersigned hereby grants to such attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact’s substitutes, shall lawfully do or cause to be done by virtue of this Power of Attorney and the rights and powers herein granted. The undersigned acknowledges that each of the foregoing attorneys-in-fact, in serving in such capacity at the request of the undersigned, is not assuming any of the undersigned's responsibilities to comply with Section 13(d), Section 16 or Section 14 of the Exchange Act.

This Power of Attorney shall remain in full force and effect until the undersigned is no longer a member of the Group unless earlier revoked by the undersigned in a signed writing delivered to the foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed as of this 11th day of January 2018.

/s/ Ezra M. Gardner

Ezra M. Gardner

POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby constitutes and appoints Jeffry R. Keyes and Thomas M. Clay or either of them as the undersigned’s true and lawful attorney-in-fact to take any and all action in connection with (i) the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of Aviragen Therapeutics, Inc. (the “Company”) directly or indirectly beneficially owned by Digirad Corporation, East Hill Management Company, LLC, Thomas M. Clay, or any of their affiliates or other persons added as members of the group (collectively, the “Group”) and (ii) any proxy solicitation of the Group (a) to elect the Group’s slate of director nominees to the board of directors of the Company and approve any proposals submitted by the Group at the next meeting of stockholders of the Company at which directors are elected and (b) for such other actions as the members of the CAS Group agree to take, including, but not limited to, soliciting stockholder support against the proposed merger between the Company and Vaxart, Inc., and for the purpose of taking all other action necessary to achieve the foregoing (collectively, the “Solicitation”). Such action shall include, but not be limited to:

1.       executing for and on behalf of the undersigned any Schedule 13D, and amendments thereto, filed by the Group that are required to be filed under Section 13(d) of the Securities Exchange Act of 1934 (the “Exchange Act”) and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

2.       executing for and on behalf of the undersigned all Forms 3, 4 and 5 required to be filed under Section 16(a) of the Securities Exchange Act of 1934 and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

3.       executing for and on behalf of the undersigned all Joint Filing and Solicitation Agreements or similar documents pursuant to which the undersigned shall agree to be a member of the Group;

4.       performing any and all acts for and on behalf of the undersigned that may be necessary or desirable to complete and execute any such document, complete and execute any amendment or amendments thereto, and timely file such form with the United States Securities and Exchange Commission and any stock exchange or similar authority; and

5.       taking any other action of any type whatsoever in connection with the Solicitation, including entering into any settlement agreement, that in the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required by, the undersigned, it being understood that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to this Power of Attorney shall be in such form and shall contain such terms and conditions as such attorney-in-fact may approve in such attorney-in-fact's discretion.

The undersigned hereby grants to such attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact’s substitutes, shall lawfully do or cause to be done by virtue of this Power of Attorney and the rights and powers herein granted. The undersigned acknowledges that each of the foregoing attorneys-in-fact, in serving in such capacity at the request of the undersigned, is not assuming any of the undersigned's responsibilities to comply with Section 13(d), Section 16 or Section 14 of the Exchange Act.

This Power of Attorney shall remain in full force and effect until the undersigned is no longer a member of the Group unless earlier revoked by the undersigned in a signed writing delivered to the foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed as of this 11th day of January 2018.

/s/ GUS D. HALAS

Gus D. Halas

POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby constitutes and appoints Jeffry R. Keyes and Thomas M. Clay or either of them as the undersigned’s true and lawful attorney-in-fact to take any and all action in connection with (i) the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of Aviragen Therapeutics, Inc. (the “Company”) directly or indirectly beneficially owned by Digirad Corporation, East Hill Management Company, LLC, Thomas M. Clay, or any of their affiliates or other persons added as members of the group (collectively, the “Group”) and (ii) any proxy solicitation of the Group (a) to elect the Group’s slate of director nominees to the board of directors of the Company and approve any proposals submitted by the Group at the next meeting of stockholders of the Company at which directors are elected and (b) for such other actions as the members of the CAS Group agree to take, including, but not limited to, soliciting stockholder support against the proposed merger between the Company and Vaxart, Inc., and for the purpose of taking all other action necessary to achieve the foregoing (collectively, the “Solicitation”). Such action shall include, but not be limited to:

1.       executing for and on behalf of the undersigned any Schedule 13D, and amendments thereto, filed by the Group that are required to be filed under Section 13(d) of the Securities Exchange Act of 1934 (the “Exchange Act”) and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

2.       executing for and on behalf of the undersigned all Forms 3, 4 and 5 required to be filed under Section 16(a) of the Securities Exchange Act of 1934 and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

3.       executing for and on behalf of the undersigned all Joint Filing and Solicitation Agreements or similar documents pursuant to which the undersigned shall agree to be a member of the Group;

4.       performing any and all acts for and on behalf of the undersigned that may be necessary or desirable to complete and execute any such document, complete and execute any amendment or amendments thereto, and timely file such form with the United States Securities and Exchange Commission and any stock exchange or similar authority; and

5.       taking any other action of any type whatsoever in connection with the Solicitation, including entering into any settlement agreement, that in the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required by, the undersigned, it being understood that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to this Power of Attorney shall be in such form and shall contain such terms and conditions as such attorney-in-fact may approve in such attorney-in-fact's discretion.

The undersigned hereby grants to such attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact’s substitutes, shall lawfully do or cause to be done by virtue of this Power of Attorney and the rights and powers herein granted. The undersigned acknowledges that each of the foregoing attorneys-in-fact, in serving in such capacity at the request of the undersigned, is not assuming any of the undersigned's responsibilities to comply with Section 13(d), Section 16 or Section 14 of the Exchange Act.

This Power of Attorney shall remain in full force and effect until the undersigned is no longer a member of the Group unless earlier revoked by the undersigned in a signed writing delivered to the foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed as of this 11th day of January 2018.

/s/ BRIAN J. HARPER

Brian J. Harper

POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby constitutes and appoints Jeffry R. Keyes and Thomas M. Clay or either of them as the undersigned’s true and lawful attorney-in-fact to take any and all action in connection with (i) the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of Aviragen Therapeutics, Inc. (the “Company”) directly or indirectly beneficially owned by Digirad Corporation, East Hill Management Company, LLC, Thomas M. Clay, or any of their affiliates or other persons added as members of the group (collectively, the “Group”) and (ii) any proxy solicitation of the Group (a) to elect the Group’s slate of director nominees to the board of directors of the Company and approve any proposals submitted by the Group at the next meeting of stockholders of the Company at which directors are elected and (b) for such other actions as the members of the CAS Group agree to take, including, but not limited to, soliciting stockholder support against the proposed merger between the Company and Vaxart, Inc., and for the purpose of taking all other action necessary to achieve the foregoing (collectively, the “Solicitation”). Such action shall include, but not be limited to:

1.       executing for and on behalf of the undersigned any Schedule 13D, and amendments thereto, filed by the Group that are required to be filed under Section 13(d) of the Securities Exchange Act of 1934 (the “Exchange Act”) and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

2.       executing for and on behalf of the undersigned all Forms 3, 4 and 5 required to be filed under Section 16(a) of the Securities Exchange Act of 1934 and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

3.       executing for and on behalf of the undersigned all Joint Filing and Solicitation Agreements or similar documents pursuant to which the undersigned shall agree to be a member of the Group;

4.       performing any and all acts for and on behalf of the undersigned that may be necessary or desirable to complete and execute any such document, complete and execute any amendment or amendments thereto, and timely file such form with the United States Securities and Exchange Commission and any stock exchange or similar authority; and

5.       taking any other action of any type whatsoever in connection with the Solicitation, including entering into any settlement agreement, that in the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required by, the undersigned, it being understood that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to this Power of Attorney shall be in such form and shall contain such terms and conditions as such attorney-in-fact may approve in such attorney-in-fact's discretion.

The undersigned hereby grants to such attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact’s substitutes, shall lawfully do or cause to be done by virtue of this Power of Attorney and the rights and powers herein granted. The undersigned acknowledges that each of the foregoing attorneys-in-fact, in serving in such capacity at the request of the undersigned, is not assuming any of the undersigned's responsibilities to comply with Section 13(d), Section 16 or Section 14 of the Exchange Act.

This Power of Attorney shall remain in full force and effect until the undersigned is no longer a member of the Group unless earlier revoked by the undersigned in a signed writing delivered to the foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed as of this 11th day of January 2018.

/s/ LEE D. KEDDIE

Lee D. Keddie

POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby constitutes and appoints Jeffry R. Keyes and Thomas M. Clay or either of them as the undersigned’s true and lawful attorney-in-fact to take any and all action in connection with (i) the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of Aviragen Therapeutics, Inc. (the “Company”) directly or indirectly beneficially owned by Digirad Corporation, East Hill Management Company, LLC, Thomas M. Clay, or any of their affiliates or other persons added as members of the group (collectively, the “Group”) and (ii) any proxy solicitation of the Group (a) to elect the Group’s slate of director nominees to the board of directors of the Company and approve any proposals submitted by the Group at the next meeting of stockholders of the Company at which directors are elected and (b) for such other actions as the members of the CAS Group agree to take, including, but not limited to, soliciting stockholder support against the proposed merger between the Company and Vaxart, Inc., and for the purpose of taking all other action necessary to achieve the foregoing (collectively, the “Solicitation”). Such action shall include, but not be limited to:

1.       executing for and on behalf of the undersigned any Schedule 13D, and amendments thereto, filed by the Group that are required to be filed under Section 13(d) of the Securities Exchange Act of 1934 (the “Exchange Act”) and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

2.       executing for and on behalf of the undersigned all Forms 3, 4 and 5 required to be filed under Section 16(a) of the Securities Exchange Act of 1934 and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

3.       executing for and on behalf of the undersigned all Joint Filing and Solicitation Agreements or similar documents pursuant to which the undersigned shall agree to be a member of the Group;

4.       performing any and all acts for and on behalf of the undersigned that may be necessary or desirable to complete and execute any such document, complete and execute any amendment or amendments thereto, and timely file such form with the United States Securities and Exchange Commission and any stock exchange or similar authority; and

5.       taking any other action of any type whatsoever in connection with the Solicitation, including entering into any settlement agreement, that in the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required by, the undersigned, it being understood that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to this Power of Attorney shall be in such form and shall contain such terms and conditions as such attorney-in-fact may approve in such attorney-in-fact's discretion.

The undersigned hereby grants to such attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact’s substitutes, shall lawfully do or cause to be done by virtue of this Power of Attorney and the rights and powers herein granted. The undersigned acknowledges that each of the foregoing attorneys-in-fact, in serving in such capacity at the request of the undersigned, is not assuming any of the undersigned's responsibilities to comply with Section 13(d), Section 16 or Section 14 of the Exchange Act.

This Power of Attorney shall remain in full force and effect until the undersigned is no longer a member of the Group unless earlier revoked by the undersigned in a signed writing delivered to the foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed as of this 11th day of January 2018.

/s/ SHAWN W. KRAVETZ

Shawn W. Kravetz

POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby constitutes and appoints Jeffry R. Keyes and Thomas M. Clay or either of them as the undersigned’s true and lawful attorney-in-fact to take any and all action in connection with (i) the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of Aviragen Therapeutics, Inc. (the “Company”) directly or indirectly beneficially owned by Digirad Corporation, East Hill Management Company, LLC, Thomas M. Clay, or any of their affiliates or other persons added as members of the group (collectively, the “Group”) and (ii) any proxy solicitation of the Group (a) to elect the Group’s slate of director nominees to the board of directors of the Company and approve any proposals submitted by the Group at the next meeting of stockholders of the Company at which directors are elected and (b) for such other actions as the members of the CAS Group agree to take, including, but not limited to, soliciting stockholder support against the proposed merger between the Company and Vaxart, Inc., and for the purpose of taking all other action necessary to achieve the foregoing (collectively, the “Solicitation”). Such action shall include, but not be limited to:

1.       executing for and on behalf of the undersigned any Schedule 13D, and amendments thereto, filed by the Group that are required to be filed under Section 13(d) of the Securities Exchange Act of 1934 (the “Exchange Act”) and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

2.       executing for and on behalf of the undersigned all Forms 3, 4 and 5 required to be filed under Section 16(a) of the Securities Exchange Act of 1934 and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

3.       executing for and on behalf of the undersigned all Joint Filing and Solicitation Agreements or similar documents pursuant to which the undersigned shall agree to be a member of the Group;

4.       performing any and all acts for and on behalf of the undersigned that may be necessary or desirable to complete and execute any such document, complete and execute any amendment or amendments thereto, and timely file such form with the United States Securities and Exchange Commission and any stock exchange or similar authority; and

5.       taking any other action of any type whatsoever in connection with the Solicitation, including entering into any settlement agreement, that in the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required by, the undersigned, it being understood that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to this Power of Attorney shall be in such form and shall contain such terms and conditions as such attorney-in-fact may approve in such attorney-in-fact's discretion.

The undersigned hereby grants to such attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact’s substitutes, shall lawfully do or cause to be done by virtue of this Power of Attorney and the rights and powers herein granted. The undersigned acknowledges that each of the foregoing attorneys-in-fact, in serving in such capacity at the request of the undersigned, is not assuming any of the undersigned's responsibilities to comply with Section 13(d), Section 16 or Section 14 of the Exchange Act.

This Power of Attorney shall remain in full force and effect until the undersigned is no longer a member of the Group unless earlier revoked by the undersigned in a signed writing delivered to the foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed as of this 11th day of January 2018.

/s/ BENJAMIN E. LARGE

Benjamin E. Large

POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby constitutes and appoints Jeffry R. Keyes and Thomas M. Clay or either of them as the undersigned’s true and lawful attorney-in-fact to take any and all action in connection with (i) the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of Aviragen Therapeutics, Inc. (the “Company”) directly or indirectly beneficially owned by Digirad Corporation, East Hill Management Company, LLC, Thomas M. Clay, or any of their affiliates or other persons added as members of the group (collectively, the “Group”) and (ii) any proxy solicitation of the Group (a) to elect the Group’s slate of director nominees to the board of directors of the Company and approve any proposals submitted by the Group at the next meeting of stockholders of the Company at which directors are elected and (b) for such other actions as the members of the CAS Group agree to take, including, but not limited to, soliciting stockholder support against the proposed merger between the Company and Vaxart, Inc., and for the purpose of taking all other action necessary to achieve the foregoing (collectively, the “Solicitation”). Such action shall include, but not be limited to:

1.       executing for and on behalf of the undersigned any Schedule 13D, and amendments thereto, filed by the Group that are required to be filed under Section 13(d) of the Securities Exchange Act of 1934 (the “Exchange Act”) and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

2.       executing for and on behalf of the undersigned all Forms 3, 4 and 5 required to be filed under Section 16(a) of the Securities Exchange Act of 1934 and the rules thereunder in connection with the undersigned’s beneficial ownership of, or participation in a group with respect to, securities of the Company or the Solicitation;

3.       executing for and on behalf of the undersigned all Joint Filing and Solicitation Agreements or similar documents pursuant to which the undersigned shall agree to be a member of the Group;

4.       performing any and all acts for and on behalf of the undersigned that may be necessary or desirable to complete and execute any such document, complete and execute any amendment or amendments thereto, and timely file such form with the United States Securities and Exchange Commission and any stock exchange or similar authority; and

5.       taking any other action of any type whatsoever in connection with the Solicitation, including entering into any settlement agreement, that in the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required by, the undersigned, it being understood that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to this Power of Attorney shall be in such form and shall contain such terms and conditions as such attorney-in-fact may approve in such attorney-in-fact's discretion.

The undersigned hereby grants to such attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact’s substitutes, shall lawfully do or cause to be done by virtue of this Power of Attorney and the rights and powers herein granted. The undersigned acknowledges that each of the foregoing attorneys-in-fact, in serving in such capacity at the request of the undersigned, is not assuming any of the undersigned's responsibilities to comply with Section 13(d), Section 16 or Section 14 of the Exchange Act.

This Power of Attorney shall remain in full force and effect until the undersigned is no longer a member of the Group unless earlier revoked by the undersigned in a signed writing delivered to the foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed as of this 11th day of January 2018.

/s/ CHAD M. NELSON

Chad M. Nelson