Acambis Identifies West Nile Vaccine Candidate

CAMBRIDGE, UK, Sept. 19, 2001 (PRIMEZONE) -- Acambis plc ("Acambis") (LSE:ACM) (Nasdaq:ACAM), announces that it has selected a vaccine candidate for the prevention of West Nile encephalitis in humans.

Acambis has developed the vaccine using its proprietary ChimeriVax technology, which is derived from the live, attenuated 17D strain of yellow fever, giving ChimeriVax vaccines a good safety profile, the ability to induce protection within a short interval after a single dose, and the potential of long-lasting immunity.

The ChimeriVax-West Nile vaccine has successfully undergone pre-clinical testing to establish its safety profile, immunogenicity and ability to protect against the West Nile virus. Acambis will now initiate manufacture of clinical trial supplies and anticipates commencing a clinical trial in 2002.

West Nile is a life-threatening virus transmitted by mosquitoes. Outbreaks have occurred in Africa, the Middle East and parts of Europe, and the virus appeared in the US for the first time in 1999. That year, 62 cases of severe disease were reported and seven deaths occurred. Since then, the virus has spread south to Florida and as far west as Illinois, and has been detected in 21 US states. In these states, more than 30 million people fall within the demographic group most at risk from the disease - those aged 55 and over.

Acambis' program to develop ChimeriVax-West Nile is being supported with a $3m grant from the US National Institutes of Health, which is expected to cover the development costs up to the point of initial human trials.

There is also a significant animal health product opportunity as horses are highly susceptible to West Nile virus. Acambis is progressing discussions on the commercialization of a veterinary vaccine with several animal health companies.

Dr John Brown, Chief Executive Officer of Acambis, said:

"We are pleased to have developed the first vaccine designed to protect against West Nile encephalitis in humans. This disease has now become established in the US and has become a significant threat to the US population."

Notes to editors:


Acambis is a biopharmaceutical company discovering, developing and manufacturing vaccine to prevent and treat infectious diseases. It has operations in Cambridge, UK, and in Cambridge and Canton, Massachusetts, USA. It has a broad portfolio of vaccine product candidates undergoing clinical trials and technology platforms that provide the basis for further vaccine product candidates.


The ChimeriVax technology platform enables the construction of vaccines against a number of viral infections caused by flaviviruses. It is derived from the live, attenuated 17D strain of the yellow fever virus, which is the basis for existing yellow fever vaccines. The genes that encode the two structural proteins in the yellow fever 17D virus are known to contain the critical antigens that confer immunity against yellow fever. To create a ChimeriVax vaccine, these genes are replaced with the corresponding genes from the target flavivirus. The resulting vaccines are designed to have a similar profile of safety and immunogenicity to that found in the yellow fever vaccine but directed against the virus whose structural protein genes are incorporated into the 17D viral genome.

The ChimeriVax technology is being used by Acambis to develop vaccines against a number of life-threatening viral diseases, including JE, dengue fever, West Nile encephalitis and Hepatitis C. The target markets for these vaccines include travelers and residents in the growing number of countries affected by these diseases.

This, and other news releases relating to Acambis, can be found on the Company's website at

This news release contains forward looking statements that involve risks and uncertainties, including the timing and results of clinical trials and other product development and commercialization risks, the risks of satisfying the regulatory approval process in a timely manner, the need for and the availability of additional capital, and other risks detailed in the Company's filings with the Securities and Exchange Commission. These forward-looking statements are based on estimates and assumptions made by the management of Acambis and are believed to be reasonable, though are inherently uncertain and difficult to predict. Actual results or experience could differ materially from the forward-looking statements.


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