EXHIBIT 23.1 CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS We consent to the use of our report dated February 21, 2002, included in the Annual Report on Form 10-K of Epimmune, Inc. for the year ended December 31, 2001, with respect to the consolidated financial statements, as amended, included in this Form 10-K/A. /s/ Ernst & Young LLP San Diego, California April 4, 2002