AVANT Immunotherapeutics and Select Vaccines Announce Partnership to Develop Improved Viral Vaccines.

Novel Virus-Like Particle Technology to be Initially Applied to Influenza Vaccines

NEEDHAM, Mass. -- AVANT Immunotherapeutics, Inc. (NASDAQ: AVAN) and Select Vaccines Limited (ASX: SLT), an Australian biotechnology company, today announced a research and development (R&D) partnership focused on the use of Select Vaccines' virus-like particles (VLPs) as a platform technology for the development of viral vaccines. The R&D efforts will initially target the development of vaccines against influenza including both epidemic and pandemic forms of vaccine, with the opportunity to expand the collaboration to other disease targets. In preclinical studies, Select Vaccines has demonstrated proof-of-principle for expressing vaccine antigens on Select VLPs with approximately 10 different antigens. Completion of the partnership agreement is subject to the approval of Select's shareholders.

"Select Vaccines' novel virus-like particles due to their specific size have the potential to generate stronger immune responses than current VLP-based vaccines," commented Una S. Ryan, Ph.D., President and Chief Executive Officer of AVANT Immunotherapeutics, Inc. "The Select Vaccine technology is particularly promising for addressing viral disease targets, which complements AVANT's bacterial vaccine pipeline and allows AVANT to more fully address the total vaccine market, which industry experts estimate will exceed $20 billion by 2010."

Under the terms of the agreement, AVANT will make an upfront equity investment in Select Vaccines and fund influenza vaccine R&D for two years, as well as provide payments to Select Vaccines for the achievement of specific preclinical and clinical development milestones. AVANT also gains the exclusive right to apply Select Vaccines' technology to a second target within the next two years, and a third target within the next three years. Select Vaccines would also be eligible to receive royalties based on net sales of any approved products arising out of this collaboration that are successfully marketed.

"We are very pleased to partner with AVANT Immunotherapeutics on the application of our VLP platform technology to this major commercial opportunity," said Martin Soust, Ph.D., Chief Executive Officer of Select Vaccines Limited. "The expression of influenza antigens identified by AVANT on Select VLPs could provide a novel vaccine candidate, distinct from other influenza VLP vaccine candidates, and could potentially stimulate a stronger immune response."

About Select Vaccines' Virus-Like Particles

Virus-like particles (VLPs) in their second-generation application are constructs that can be engineered to carry foreign antigens on their surface and mimic viruses in their ability to stimulate strong immune responses, in this case against foreign antigens. Two types of licensed vaccines (hepatitis B and human papilloma virus vaccines) and several vaccine candidates employ first-generation VLP technology, thus providing proof-of-concept for this approach to vaccine delivery.

"Select Vaccines has developed novel VLPs that differ from previous approaches in several ways that suggest they may offer a particularly robust and flexible platform for vaccine development," said Ronald W. Ellis, Ph.D., AVANT's Senior Vice President, R&D. First, Select VLPs have a specific size and assembly process different from other VLPs which enables the expression of much larger vaccine antigens than can be expressed on other types of VLPs and also offers the prospect for distinctive antigen processing. At the same time, Select VLPs are themselves more weakly immunogenic than other VLPs, which should better focus the induced antibody response on the expressed vaccine antigen instead of on the VLP carrier itself." A further benefit of Select's technology is the ability to manufacture their VLPs in yeast, thus doing away with the need to grow flu vaccines in eggs, a slow, time-consuming and inefficient process.

Market Opportunity for Influenza Vaccines

The global influenza vaccine market is projected to grow to as much as 370 million doses with a value of $3.7 billion by 2010, up from an estimated $1.3 billion in the 2003-2004 season as a result of commercial drivers encouraging higher influenza vaccine availability in the near to long term. The U.S. market alone will potentially account for 176 million doses and $1.8 billion in value by 2010.1

About Select Vaccines Limited

Select Vaccines listed on the ASX on 3 July 2003. It is developing products which identify and protect against infectious diseases of global and national importance and which satisfy the needs of other pharmaceutical and biotechnology companies. Select Vaccine's pipeline includes products targeting flu, hepatitis C, and malaria. It is in partnership with Melbourne's Burnet Institute to commercialize research outcomes in the area of infectious disease. The Burnet Institute, established in 1986, is Australia's leading research organization in the field of infectious diseases caused by viruses and other agents. Further information can be found on the company's website: www.selectvaccines.com.au.

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 five of AVANT's products are in clinical development. AVANT's pipeline includes products for biodefense, travelers' vaccines, global health, and pandemic flu needs based on AVANT's oral, rapid-protecting, single-dose and temperature stable vaccine technology. AVANT is also developing a treatment to reduce complement- mediated tissue damage associated with cardiac bypass surgery and a novel vaccine for cholesterol management.

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 development and commercialization of TP10, CETi-1, CholeraGarde[R] (Peru-15), Ty800, ETEC E. coli and other products; (4) the cost, timing, scope and results of ongoing safety and efficacy trials of TP10, CETi-1, CholeraGarde[R] (Peru-15), Ty800, ETEC E. coli and other preclinical and clinical testing; (5) the ability to successfully complete product research and further development, including animal, pre-clinical and clinical studies of TP10, CETi-1, CholeraGarde[R] (Peru-15), Ty800, ETEC E. coli and other products; (6) the ability of the Company to manage multiple late stage clinical trials for a variety of product candidates; (7) the volume and profitability of product sales of Megan[R]Vac 1, Megan[R]Egg and other future products; (8) the process of obtaining regulatory approval for the sale of Rotarix[R] in major commercial markets, as well as the timing and success of worldwide commercialization of Rotarix[R] by our partner, Glaxo; (9) Glaxo's strategy and business plans to launch and supply Rotarix[R] worldwide, including in the U.S. and other major markets and its payment of royalties to AVANT; (10) changes in existing and potential relationships with corporate collaborators; (11) the availability, cost, delivery and quality of clinical and commercial grade materials supplied by contract manufacturers; (12) the timing, cost and uncertainty of obtaining regulatory approvals to use TP10, CETi-1, CholeraGarde[R] (Peru-15) and Ty800, ETEC E. coli, among other purposes, for adults undergoing cardiac surgery, to raise serum HDL cholesterol levels and to protect travelers and people in endemic regions from diarrhea causing diseases, respectively; (13) the ability to obtain substantial additional funding; (14) the ability to develop and commercialize products before competitors and that are superior to the alternatives developed by competitors; (15) the ability to retain certain members of management;(16) AVANT's expectations regarding research and development expenses and general and administrative expenses; (17) DVC's ability to complete clinical trials and perform under its agreement; (18) AVANT's expectations regarding CETP's ability to improve cholesterol levels and AVANT's ability to develop and commercialize CETP; (19) AVANT's expectations regarding cash balances, anticipated royalty payments (including those from Glaxo) and expenses, including infrastructure expenses; and (20) other factors detailed from time to time in filings with the Securities and Exchange Commission. 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 report, and we do not promise to update any forward-looking statements to reflect changes in underlying assumptions or factors, new information, future events or other changes.

1 Datamonitor report: Stakeholder Perspectives: Influenza Vaccines; DMHC2156, December 2005.