Acambis to collaborate with Cangene to develop West Nile hyperimmune

Cambridge, UK and Cambridge, Massachusetts - 3 September 2003 - Acambis plc
("Acambis") (LSE: ACM, NASDAQ: ACAM) announces that it has entered into a
collaboration with Cangene Corporation ("Cangene") (TSE: CNJ) to develop a
hyperimmune globulin for prevention and treatment of West Nile virus disease.

The agreement brings together the vaccine Acambis is developing against West
Nile, ChimeriVax-West Nile, and Cangene's capability in the development and
manufacture of hyperimmune products. Hyperimmune globulins are highly purified
antibodies produced from human plasma. A hyperimmune globulin against West Nile
can be used to treat people who have become infected with the virus and to give
immediate protection to immunocompromised individuals, such as the elderly,
whose immune systems may not be able to generate a sufficient immune response.

Acambis and Cangene will both participate in the development work for the West
Nile hyperimmune globulin and share the costs of funding the project. Acambis
will make available to Cangene its ChimeriVax-West Nile vaccine, which will be
used to vaccinate Cangene's plasma donors to generate the hyperimmune globulin
against West Nile virus.

West Nile virus is a flavivirus transmitted by mosquitoes. It was first
identified in North America in 1999 when an outbreak in New York City and four
US States resulted in 62 cases and seven deaths. By the end of 2002, it had
spread to a total of 44 US States, resulting in 4,156 diagnosed cases and the
death of 284 people. The first human cases were also identified in five
Canadian provinces and the virus spread south into Mexico.

Acambis has developed its vaccine using its proprietary ChimeriVaxTM technology
and has recently filed an Investigational Drug Application with the US Food and
Drug Administration to undertake a Phase I trial of its ChimeriVax-West Nile
vaccine.

Dr John Brown, CEO of Acambis, commented:

"This collaboration is an ideal pairing of the West Nile vaccine that Acambis
has developed with Cangene's technology and considerable expertise in the
generation of hyperimmune products. This is an interesting opportunity to
explore the potential for a product against West Nile that complements the
vaccine we are currently developing and could enable us to provide protection
for as wide a range of people as possible."

Dr John Langstaff, President and CEO of Cangene, said:

"West Nile spread across North America at an astonishing rate and has rapidly
established itself as a public health concern. With operations in Manitoba and
Ontario, we are acutely aware of the threat of mosquito-borne infections and we
believe that hyperimmune technology is well suited to meet the challenge."

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Enquiries:

Acambis plc                              Cangene Corporation                   
                                                                               
Dr John Brown, Chief Executive Officer   Jean Compton, Manager, Investor       
                                         Relations                             
Gordon Cameron, Chief Financial Officer                                        
                                         Tel: +1 (905) 405 2900                
Tel: +1 (617) 761 4200                                                         
                                                                               
Lyndsay Wright, Director of                                                    
Communications                                                                 
                                                                               
Tel: +44 (0) 1223 275 300                                                      
                                                                               
Financial Dynamics                                                             
                                                                               
David Yates/Jonathan Birt                                                      
                                                                               
Tel: +44 (0) 20 7831 3113                                                      

Notes to editors:

Acambis plc

Acambis is a leading developer of vaccines to prevent and treat infectious
diseases. Recognised internationally as the leading producer of smallpox
vaccines, Acambis provides governments around the world with the full portfolio
of related smallpox vaccine products required to protect their citizens against
the threat of smallpox virus being used as a bioterrorist weapon. Acambis is
establishing a travel vaccines franchise, including vaccines against yellow
fever, Japanese encephalitis, dengue fever and typhoid. Acambis also has the
most advanced vaccine in development targeting the West Nile virus, which has
spread to over 40 US States in the last three years.

Acambis is based in Cambridge, UK and Cambridge, Massachusetts, US. Its primary
listing is on the London Stock Exchange (ACM) and its shares are listed in the
form of American Depositary Receipts on Nasdaq (ACAM). More information is
available at www.acambis.com.

Cangene Corporation

Cangene is one of Canada's largest biotechnology companies. Founded in 1984 in
Mississauga, Cangene is headquartered in Winnipeg and carries on research and
development activities in both cities. It uses patented manufacturing processes
to produce plasma-derived and recombinant therapeutic proteins. The Company
currently has two approved products and a significant clinical trial program
including a Vaccinia immunoglobulin (VIG), two products nearing regulatory
submission, and one that has been submitted for FDA review. Cangene is also
expanding its contract research and manufacturing businesses using its
drug-manufacturing expertise and the resources of Chesapeake Biological
Laboratories, Inc. (a wholly-owned subsidiary). The Company's
internationally-compliant, ISO 9001-registered manufacturing facilities are
located in Winnipeg, Manitoba and Baltimore, Maryland. Cangene's website, 
www.cangene.com, includes product and investor information, including past news
releases. Chesapeake's website is www.cblinc.com.

"Safe Harbor" statement under the Private Securities Litigation Reform Act of
1995:

The statements in this news release that are not historical facts are
forward-looking statements that involve risks and uncertainties, including the
timing and results of clinical trials, product development, manufacturing and
commercialisation risks, the risks of satisfying the regulatory approval
process in a timely manner, the need for and the availability of additional
capital. For a discussion of these and other risks and uncertainties see "Risk
factors" in the Company's Annual Report and Form 20-F for the most recently
ended fiscal year, in addition to those detailed in the Company's filings made
with the Securities and Exchange Commission from time to time. 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.



END