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Vical Reports Publication of Key Research Findings for Immunotherapeutic Herpes Vaccine

SAN DIEGO, April 23, 2009 (GLOBE NEWSWIRE) -- Vical Incorporated (Nasdaq:VICL) today announced the publication in the May 1 issue of the Journal of General Virology(1) of data from preclinical studies identifying potential targets for development of a herpes simplex virus type 2 (HSV-2) vaccine. HSV-2 is a sexually transmitted virus which is the leading cause of genital herpes. The vaccine under development will be designed for use in people already infected with HSV-2, with the goal of reducing or eliminating periodic viral flare-ups and the associated viral shedding and transmission. The HSV-2 vaccine, being developed under a previously disclosed grant(2), will be evaluated with Vical's novel Vaxfectin(r) adjuvant.

HSV-2 Disease Burden

All HSV-2 infections are persistent and result in periodic virus shedding. In the United States, at least 40 million people are infected with HSV-2, and approximately 1.6 million people are newly infected each year, with approximately 500,000 of those suffering from disease symptoms. Even higher infection rates are evident in developing countries, with further complications in people also infected with HIV. There is currently no approved vaccine for HSV-2. Although antiviral regimens have become a standard of care, their inconvenience, cumulative cost over the years and potential for drug resistance highlight the need for safe, new approaches to reducing HSV-2 lesions, shedding, and transmission. Estimated direct costs of treating HSV-2 in the United States alone are close to $1 billion annually, primarily for drugs and outpatient medical care, plus additional indirect costs of more than $200 million.

Research Findings

David Koelle, M.D., professor of medicine in the Division of Allergy and Infectious Diseases at the University of Washington School of Medicine, an investigator supported by Vical's grant and the article's senior author, said, "We are encouraged that the CD8 T-cell responses observed in mice after DNA vaccination matched those observed after natural HSV-2 infection, suggesting that the appropriate tegument protein epitopes together with surface glycoproteins may provide interventional vaccine opportunities. We believe these responses may be important in controlling HSV-2 reactivation and the related genital lesions. Our goal is to manage established HSV-2 infection to reduce both disease symptoms and the potential to infect others. We look forward to advancing a suitable vaccine candidate toward human clinical testing."

The article's authors identified key epitopes, or sections, of the HSV-2 tegument proteins VP11/12, VP/13/14 and VP22. Tegument proteins are structural components between the inner core and outer envelope of the virus. Tegument-specific T cells are prevalent and abundant in humans, suggesting their importance in control of the virus. The authors demonstrated that pDNA vaccination encoding these antigens induced the same specificities of T cells produced after natural HSV-2 infection. Based on these studies the authors concluded that mice, like humans, generate T-cell responses against tegument protein epitopes and that these tegument proteins, together with the HSV-2 envelope glycoprotein D (gD) also evaluated in the experiments, are rational candidates for further HSV-2 vaccine research.

About Vical

Vical researches and develops biopharmaceutical products based on its patented DNA delivery technologies for the prevention and treatment of serious or life-threatening diseases. Potential applications of the company's 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. The company is developing certain infectious disease vaccines and cancer therapeutics internally. In addition, the company collaborates with major pharmaceutical companies and biotechnology companies that give it access to complementary technologies or greater resources. These strategic partnerships provide the company with mutually beneficial opportunities to expand its product pipeline and address significant unmet medical needs. Additional information on Vical is available at

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This press release contains forward-looking statements subject to risks and uncertainties that could cause actual results to differ materially from those projected, including: whether all funding under the grant will be received by the company; whether the development efforts will result in a vaccine that can generate immune responses sufficient to reduce or eliminate periodic viral flare-ups and the associated viral shedding and transmission; whether the Vaxfectin(r) adjuvant will effectively enhance the performance of the HSV-2 vaccine; whether Vical or others will advance the HSV-2 vaccine candidate into human clinical testing; whether Vical or its collaborative partners will seek or gain approval to market any product candidates; whether Vical or its collaborative partners will succeed in marketing any product candidates; 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.

(1) Muller WJ et al. Herpes simplex virus type 2 tegument proteins contain subdominant T-cell epitopes detectable in BALB/c mice after DNA immunization and infection. J Gen Virol 2009; 90:1153-1163.

(2) Vical is collaborating in the preclinical development of an immunotherapeutic HSV-2 pDNA vaccine with the University of Washington School of Medicine and the University of Texas Medical Branch under a two-year, $2.0 million Phase II Small Business Technology Transfer grant from the U.S. National Institute of Allergy and Infectious Diseases of the National Institutes of Health, an agency of the U.S. Department of Health and Human Services.

CONTACT: Vical Incorporated Alan R. Engbring (858) 646-1127

Posted: April 2009