AVANT Commences Phase 2 Clinical Trial of Its Single Dose, Oral Typhoid Fever Vaccine.

NEEDHAM, Mass. -- AVANT Immunotherapeutics, Inc. (Nasdaq: AVAN) announced today the initiation of enrollment in a randomized, placebo-controlled, double-blind Phase 2 study of its typhoid fever vaccine candidate, Ty800, in approximately 180 healthy adult volunteers. The Phase 2 study is an out-patient, dose-ranging clinical trial that will evaluate two dose levels of the single-dose, oral Ty800 vaccine and will follow each subject for six months post-vaccination. The objectives of this Phase 2 study are to determine the optimal dose of Ty800 for further development based on the safety, reactogenicity, and immunogenicity of the vaccine. The study is being conducted by Accelovance Inc. of Rockville, MD at five clinical sites across the United States.

"We are delighted to be initiating clinical testing of our single-dose, oral Ty800 vaccine," said Una S. Ryan, President and Chief Executive Officer of AVANT Immunotherapeutics, Inc. "The development of a safe and effective typhoid fever vaccine is important for protecting residents, travelers and military personnel from typhoid fever in endemic areas. We see the commencement of this trial as serving the dual role of addressing a significant health issue in the developing world and advancing development of AVANT's bacterial vaccine franchise. AVANT is advancing its programs towards creating a "Super Combination Traveler's Vaccine". Our "Super Vaccine" is designed to capture the potential of our single-dose oral delivery platforms to combine protection against multiple bacterial diseases including cholera, typhoid, ETEC (enterotoxigenic E. coli) and paratyphoid into one convenient and efficient vaccine for world travelers."

AVANT has designed the Ty800 vaccine to offer rapid, oral, single-dose protection against Salmonella typhi, the cause of typhoid fever. The Ty800 vaccine was developed using genetic techniques to delete specific genes known to be essential to the virulence of S. typhi. The clinical trial is designed to show that Ty800 is well tolerated in humans and rapidly elicits strong immune responses.

About Typhoid Fever

Typhoid fever is a potentially life-threatening infection of the intestinal tract caused by the bacterium Salmonella typhi. It is transmitted by ingestion of food or water contaminated by the feces from an infected person. According to the Centers for Disease Control, an estimated 22 million cases of typhoid fever and 200,000 related deaths occur worldwide each year. In the United States, incidence of the disease is reported mainly in recent travelers to areas of the world where typhoid fever is endemic. Risk is greatest for travelers to South Asia and developing countries in Asia, Africa, the Caribbean and Central and South America. There are two current vaccines for typhoid fever, a four-dose oral vaccine and an intramuscularly injected vaccine, both of which provide protection to only 50-80% of recipients.

About AVANT Immunotherapeutics, Inc.

AVANT Immunotherapeutics, Inc. discovers and develops innovative vaccines and therapeutics that harness the human immune system to prevent and treat disease. AVANT has three products on the market and four of AVANT's products are in clinical development. AVANT's pipeline includes products for travelers' vaccines and global health needs based on AVANT's oral, rapid-protecting, single-dose and temperature-stable vaccine technology. Additional information on AVANT Immunotherapeutics, Inc. can be obtained through our site on the World Wide Web: http://www.avantimmune.com.

Safe Harbor Statement Under the Private Securities Litigation Reform Act of 1995: This release includes forward-looking statements that are subject to a variety of risks and uncertainties and reflect AVANT's current views with respect to future events and financial performance. There are a number of important factors that could cause the actual results to differ materially from those expressed in any forward-looking statement made by AVANT. These factors include, but are not limited to: (1) the integration of multiple technologies and programs; (2) the ability to adapt AVANT's vectoring systems to develop new, safe and effective orally administered vaccines against anthrax and plague or other any other microbes used as bioweapons and other disease causing agents; (3) the ability to successfully complete product research and further development, including animal, pre-clinical and clinical studies, and commercialization of CholeraGarde[R] (Peru-15), Ty800, ETEC E. coli vaccine, VLPs and other products and AVANT's expectations regarding market growth; (4) the cost, timing, scope and results of ongoing safety and efficacy trials of CholeraGarde[R] (Peru-15), Ty800, ETEC E. coli vaccine and other preclinical and clinical testing; (5) the ability to negotiate strategic partnerships or other disposition transactions for AVANT's cardiovascular programs, including TP10 and CETi; (6) the ability of AVANT to manage multiple clinical trials for a variety of product candidates; (7) AVANT's expectations regarding its technological capabilities and expanding its focus to broader markets for vaccines; (8) the Company's expectations regarding the cost of funding its development partnership with Select Vaccines Limited for the influenza vaccine, the opportunity to extend to other disease targets, and AVANT's ability to develop products through this collaboration; (9) changes in existing and potential relationships with corporate collaborators; (10) the availability, cost, delivery and quality of clinical and commercial grade materials produced at AVANT's own Manufacturing facility or supplied by contract manufacturers and partners; (11) the timing, cost and uncertainty of obtaining regulatory approvals; (12) the ability to develop and commercialize products before competitors that are superior to the alternatives developed by competitors; (13) the ability to retain certain members of management;(14) AVANT's expectations regarding research and development expenses and general and administrative expenses; (15) AVANT's expectations regarding cash balances, capital requirements, anticipated royalty payments (including those from Paul Royalty Fund), revenues and expenses, including infrastructure expenses; (16) our belief regarding the validity of our patents and potential litigation; and (17) certain other factors that might cause AVANT's actual results to differ materially from those in the forward-looking statements including those set forth under the headings "Business," "Risk Factors" and Management's Discussion and Analysis of Financial Condition and Results of Operations" in each of AVANT's Annual Report on Form 10-K, its Quarterly Reports on Form 8-K, as well as those described in AVANT's other press releases and filings with the Securities and Exchange Commission, from time to time. You should carefully review all of these factors, and you should be aware that there may be other factors that could cause these differences. These forward-looking statements were based on information, plans and estimates at the date of this press release, and AVANT does not promise to update any forward-looking statements to reflect changes in underlying assumptions or factors, new information, future events or other changes.