Filed by: V.I. Technologies, Inc.

Pursuant to Rule 425 under the Securities Act of 1933

and deemed filed pursuant to Rule 14a-12 of the

Securities Exchange Act of 1934

Subject Company: Panacos Pharmaceuticals, Inc.

Exchange Act File No. 000-24241

Notice to Shareholders

Vitex filed a Registration Statement on Form S-4, as amended, in connection with the merger, and Vitex and Panacos mailed a Joint Proxy Statement/Prospectus to their stockholders containing information about the merger. Investors and security holders are urged to read the Registration Statement and the Joint Proxy Statement/Prospectus carefully. The Registration Statement and the Joint Proxy Statement/Prospectus contain important information about Vitex, Panacos, the merger and related matters. Investors and security holders can obtain free copies of these documents through the web site maintained by the U.S. Securities and Exchange Commission at http//www.sec.gov, and by calling Vitex Investor Relations at 617-926-1551.

Vitex and Panacos, and their respective directors, executive officers and certain members of management and employees will be soliciting proxies from Vitex and Panacos stockholders in favor of the adoption of the merger agreement and the transactions associated with the merger. A description of any interests that Vitex’s and Panacos’ directors and executive officers have in the merger are available in the Joint Proxy Statement/Prospectus.

PRESS RELEASE ISSUED 8/9/04

CONTACTS:

John R. Barr

President and CEO

617-926-1551

john.barr@vitechnologies.com

Thomas T. Higgins

Executive Vice President, Operations and CFO

617-926-1551

tom.higgins@vitechnologies.com

Proposed Merger Between V.I. Technologies and Panacos Pharmaceuticals

Receives Recommendation From Institutional Shareholder Services

Watertown, MA (August 9, 2004) — V.I. Technologies, Inc. (Nasdaq: VITX) (“Vitex” or “the Company”), a biotechnology company dedicated to developing the next generation of anti-infective products, today announced it has learned that Institutional Shareholder Services, Inc (“ISS”), a leading provider of proxy advisory services to institutional investors,

mutual funds and other fiduciaries, has recommended to its clients that they vote FOR the merger agreement between Vitex and Panacos Pharmaceuticals. ISS has also recommended that its clients vote FOR the proposal to approve the adoption of a supplemental stock option plan and FOR the proposal to increase the Company’s authorized common stock.

About Vitex

Vitex is developing the next generation of anti-infective products. The Company’s proprietary INACTINE^™ technology, currently in a Phase III clinical trial for use in acute transfusions, is designed to inactivate a wide range of viruses, bacteria and parasites in units of red blood cells, and has also demonstrated its ability to remove prion proteins from red cell units. Over 40 million red cell units are transfused annually in the U.S., Europe and Japan. For more information on Vitex, please visit our web site at: http://www.vitechnologies.com.

Vitex recently announced that it has entered into a definitive merger agreement with privately-held Panacos Pharmaceuticals, a biotechnology company discovering and developing novel antiviral drugs for the treatment of HIV and other major human viral diseases. Terms of the merger, which is subject to the approval of the shareholders of Vitex and Panacos, are contained in the Joint Proxy Statement/ Prospectus dated July 13, 2004 and in the Form S-4 Registration Statement on file with the Securities and Exchange Commission. The merger is expected to close during August 2004.

Vitex makes no warranty, express or implied, regarding the accuracy, completeness, or usefulness of the information contained in the ISS report, and assumes no liability with respect to the consequences of relying on the information contained in the ISS report for investment or other purposes.

Except for the historical information contained herein, the matters discussed are forward-looking statements made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. These statements involve risks and uncertainties, such as execution of the Company’s financing plans, quarterly fluctuations in operating results, anticipated clinical trial timelines or results, the timely availability of new products, market acceptance of the Company’s products, the impacts of competitive products and pricing, government regulation of the Company’s products and other risks and uncertainties set forth in the Company’s filings with the Securities and Exchange Commission. These risks and uncertainties could cause actual results to differ materially from any forward-looking statements made herein.

Vitex filed a Registration Statement on Form S-4, as amended, in connection with the merger, and Vitex and Panacos have mailed a Joint Proxy Statement/Prospectus to their stockholders containing information about the merger. Investors and security holders are urged to read the Registration Statement and the Joint Proxy Statement/Prospectus carefully. The Registration Statement and the Joint Proxy Statement/Prospectus contain

important information about Vitex, Panacos, the merger and related matters. Investors and security holders can obtain free copies of these documents through the web site maintained by the U.S. Securities and Exchange Commission at http://www.sec.gov, and by calling Vitex Investor Relations at 617-926-1551.

Vitex and Panacos, and their respective directors, executive officers and certain members of management and employees will be soliciting proxies from Vitex and Panacos stockholders in favor of the adoption of the merger agreement and the transactions associated with the merger. A description of any interests that Vitex’s and Panacos’ directors and executive officers have in the merger is available in the Joint Proxy Statement/Prospectus.