July 15, 2003

News Release: Vical to Manufacture West Nile Virus Vaccine

Vical Incorporated (Nasdaq: VICL) announced today that the company has been requested to manufacture clinical-grade supplies of an experimental DNA vaccine against the West Nile Virus for development planned by the Vaccine Research Center (VRC), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH). The new West Nile Virus vaccine manufacturing agreement is in addition to Vical's large-scale DNA vaccine manufacturing subcontract announced in May 2003, and Vical's Ebola DNA vaccine manufacturing subcontract announced in July 2002; all of the contracts are issued and managed on behalf of NIAID's Vaccine Research Center by SAIC Frederick, Inc. under the umbrella of a federally funded prime contract with NIH. Vical's President and Chief Executive Officer, Vijay B. Samant, said, 'Vical's DNA delivery technology offers a unique opportunity to shorten vaccine development timelines. The 'plug and play'nature of our gene delivery method allows rapid evaluation of candidate immunogens, which can cut years from the total vaccine development cycle. We already have begun production of the West Nile Virus vaccine under this new agreement. Another benefit of using Vical's technology platform for such virulent agents is that development and production of vaccines do not involve any handling of the pathogen itself. These speed and safety advantages are extremely important for emerging diseases such as West Nile Virus, Ebola, SARS and others, which can spread rapidly if unchecked by either natural or conferred immunity. DNA vaccines for a wide variety of infectious diseases are under development by Vical, its licensees, and others.

'Through this collaboration, our technology has the potential to yield the first approvable human vaccine for West Nile Virus. The vaccine construct incorporates West Nile Virus gene sequences known to be immunogenic. We are pleased to apply our expertise and manufacturing resources in support of the VRC's West Nile Virus vaccine program, and we look forward to the development of an effective vaccine against this emerging disease.'

West Nile Virus has been an increasing seasonal threat in the United States over the past several years, causing growing numbers of cases and deaths in birds, horses, and humans each summer. The disease is spread by many species of mosquitoes, which carry the virus from host to host. Most infected people have no disease symptoms, and some have only mild symptoms. But approximately one out of every 150 infected people develops serious disease symptoms of the central nervous system, including headache, high fever, tremors, convulsions, numbness, vision loss, coma, and paralysis lasting several days to several weeks, potentially with some permanent neurological damage. Most West Nile Virus deaths are caused by encephalitis, a severe swelling of the brain, or meningitis, a severe swelling of the membrane surrounding the brain and spinal cord.

Conventional vaccines, using whole killed West Nile Virus, are available for horses and for some species of birds. To develop a human vaccine using this approach, however, could require many years of further development and testing to provide sufficient proof of safety and effectiveness.

This new activity does not affect the company's net loss forecast for 2003.

About Vical

Vical researches and develops biopharmaceutical products based on our patented DNA delivery technologies for the prevention and treatment of serious or life-threatening diseases. Potential applications of our DNA delivery technology include DNA vaccines for infectious diseases or cancer, in which the expressed protein is an immunogen; cancer immunotherapeutics, in which the expressed protein is an immune system stimulant; and cardiovascular therapies, in which the expressed protein is an angiogenic growth factor. We have retained all rights to our internally developed product candidates. In addition, we collaborate with major pharmaceutical companies and biotechnology companies that give us access to complementary technologies or greater resources. These strategic partnerships provide us with mutually beneficial opportunities to expand our product pipeline and serve significant unmet medical needs.

This press release contains forward-looking statements subject to risks and uncertainties that could cause actual results to differ materially from those projected. Forward-looking statements include statements about the advantages of using Vical's DNA delivery technology in the development of vaccines against West Nile Virus or other infectious diseases, the makeup, development, uses and beneficial effects of such vaccines, the lack of impact upon Vical's financial forecast, as well as the company's focus, collaborative partners, product candidates, and developmental status. Risks and uncertainties include whether vaccines for West Nile Virus or other infectious diseases will be developed and approved, whether use of Vical's technology in such vaccines will provide protective immune responses to such diseases and will result in products that are safer, simpler and faster to manufacture than traditional vaccines, whether any product candidates will be shown to be safe and efficacious in clinical trials, the timing of clinical trials, whether Vical or its collaborative partners will seek or gain approval to market any product candidates, the dependence of the company on its collaborative partners, and additional risks set forth in the company's filings with the Securities and Exchange Commission. These forward-looking statements represent the company's judgment as of the date of this release. The company disclaims, however, any intent or obligation to update these forward-looking statements.

For further information, please contact Investors, Alan R. Engbring of Vical Incorporated, +1-858-646-1127; or Media, Janeen Hicks of Atkins + Associates, +1-858-527-3486, for Vical Incorporated.

SOURCE Vical Incorporated

Investors, Alan R. Engbring of Vical Incorporated, +1-858-646-1127; or Media, Janeen Hicks of Atkins + Associates, +1-858-527-3486, for Vical Incorporated

http://www.vical.com

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