Exhibit 23.3

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the use in this Amendment No. 4 to the Registration Statement on Form S-4 of Trimeris, Inc. of our report dated July 12, 2011 relating to the financial statements of Synageva BioPharma Corp., which appears in such Registration Statement. We also consent to the reference to us under the heading “Experts” in such Registration Statement.

/s/ PricewaterhouseCoopers LLP

PricewaterhouseCoopers LLP

Boston, Massachusetts

October 11, 2011