Date: 5/23/2007 6:35:00 AM

MALAGA, Spain, May 23 /PRNewswire-FirstCall/ -- Vical Incorporated (Nasdaq: VICL) today announced that in a recently completed animal study, a DNA vaccine formulated with the company's patented Vaxfectin(TM) adjuvant and delivered by needle-free injection yielded significantly higher antibody responses than an unformulated DNA vaccine delivered by needle and syringe. In a separate animal study, electroporation following injection of unformulated vaccine yielded comparable improvements in antibody responses, but electroporation required anesthesia of the animals while needle-free injection of Vaxfectin(TM)-formulated vaccine was administered safely and tolerably without anesthesia.

"The dose-sparing and immunogenicity-enhancing capabilities of the Vaxfectin(TM) adjuvant have been demonstrated in a range of vaccine applications in various animal models," said Alain P. Rolland, Pharm.D., Ph.D., Vical's Senior Vice President of Product Development, "but the potential safety and tolerability advantages of Vaxfectin(TM) compared with alternative DNA delivery enhancement options are making it our preferred choice for new development projects. We look forward to beginning the initial human testing of a Vaxfectin(TM)-formulated DNA vaccine for pandemic influenza, anticipated in the second half of 2007, and to continued exploration of Vaxfectin(TM)'s use in optimizing efficacy and safety for future prophylactic or therapeutic applications."

Both studies were conducted in rabbits with DNA vaccines encoding cytomegalovirus (CMV) glycoprotein B (gB). The vaccines were either unformulated -- using standard phosphate-buffered saline (PBS) -- or formulated -- using the company's Vaxfectin(TM) adjuvant in PBS. Vaxfectin(TM)-formulated vaccines were injected with a needle-free device. Unformulated vaccines were injected with needle and syringe followed in some animals by electroporation using either a constant voltage multi-needle device or a constant current multi-needle device. Both electroporation devices and the Vaxfectin(TM)/needle-free device combination elicited significant increases in production of gB-specific antibodies compared with unformulated vaccine delivered by needle and syringe alone and all three enhancements elicited comparable production of gB-specific antibodies.

Vical research scientist Jukka Hartikka, Ph.D., presented the data at the DNA Vaccines 2007 conference (Malaga, Spain, May 23 - 25). Other topics of interest at the conference included a novel potency assay for DNA vaccines, presented by Keith Hall, Vical's Senior Director of Quality Control and Assay Development; and a DNA vaccine for cancer, presented by Vical's licensee, Merck & Co., Inc.

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 www.vical.com.

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 Vical or others will continue development of DNA vaccines; whether Vaxfectin(TM) formulation, needle-free delivery or electroporation will sufficiently enhance immunogenicity of DNA vaccines; whether initial human testing of a Vaxfectin(TM)-formulated DNA vaccine for pandemic influenza will begin as planned, if at all; whether safety and tolerability demonstrated in animal studies will correlate to results in humans; whether additional enhancement options may become available, and if so, whether they will be used in future applications; whether any product candidates will be shown to be safe and effective in clinical trials; the timing, nature and cost of clinical trials; whether Vical or others will seek or gain approval to market any product candidates; whether Vical or others 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.

    Contacts:  Investors:                     Media:
               Alan R. Engbring               Susan Neath
               Vical Incorporated             Porter Novelli Life Sciences
               (858) 646-1127                 (619) 849-6007
               Website: www.vical.com


SOURCE  Vical Incorporated
    -0-                             05/23/2007
    /CONTACT:  Investors, Alan R. Engbring of Vical Incorporated,
+1-858-646-1127; or Media, Susan Neath of Porter Novelli Life Sciences,
+1-619-849-6007, for Vical Incorporated/
    /Web site:  http://www.vical.com /
    (VICL)

CO:  Vical Incorporated
ST:  Spain, California
IN:  HEA MTC BIO
SU:  TRI TDS

TU
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2319 05/23/2007 06:35 EDT http://www.prnewswire.com