Vical DNA Delivery Technology Enters Clinical Trial for Therapeutic
                                 HIV Vaccine
    SAN DIEGO, Aug. 22 /PRNewswire-FirstCall/ -- Vical Incorporated
(Nasdaq: VICL) announced today the initiation of a National Institutes of
Health (NIH) sponsored Phase 1 clinical trial of a "prime-boost" vaccine
approach designed to prevent or control disease in patients already infected
with HIV.  The trial involves priming an immune response with multiple doses
of a plasmid DNA vaccine, based on Vical's proprietary DNA delivery
technology, and boosting the response with a single dose of adenoviral vector
vaccine given at a later date.

    The vaccine was developed by scientists at the Dale and Betty Bumpers
Vaccine Research Center (VRC) of the National Institute of Allergy and
Infectious Diseases (NIAID), part of the NIH, and was manufactured by Vical.
The vaccine incorporates HIV genetic material from the three most globally
important HIV subtypes, clades A, B and C, which are involved in about
85 percent of all HIV infections around the world.  The same vaccine is
currently being tested in a preventive setting through a multinational Phase 2
trial initiated in October 2005.  Results from a Phase 1 trial in
HIV-uninfected subjects showed that the prime-boost approach was well
tolerated and effective in producing potent cellular and antibody immune
responses, including specific responses against each of the HIV subtypes.  The
new Phase 1 trial is the first therapeutic application of a "prime/boost"
vaccine against HIV in the VRC program.

    "Antiviral drugs have dramatically improved the outlook for HIV-infected
individuals," said Vijay B. Samant, Vical's President and Chief Executive
Officer, "but complicated treatment regimens, serious side effects and
increasing drug resistance call for better long-term solutions.  A
post-infection vaccine that would allow the immune system to suppress viral
loads could provide significant benefits both to prevent disease symptoms in
the individual and potentially to reduce disease transmission between
individuals. We are excited that our collaborators at the VRC have advanced
into human testing with this novel vaccine application."

    The vaccine used in the Phase 1 trial incorporates parts of four HIV
genes. Three of these vaccine components are modified versions of HIV genes
called gag, pol and nef, synthetically made based on sequence from clade B,
the subtype that predominates in Europe and North America.  The fourth vaccine
component is a modified version of the HIV gene named env.  The env gene codes
for a protein on the outer coat of the virus that allows it to recognize and
attach to human cells.  VRC scientists were the first to combine modified env
from clades A and C, which are the most common in Africa and parts of Asia,
with the modified env gene from clade B.  The study is being conducted at the
NIH Clinical Center.  The trial is double-blinded and placebo-controlled, and
will evaluate safety, tolerability and immune response.  Subjects will
continue highly active antiretroviral therapy (HAART) throughout the trial.

    Vical has produced multiple DNA vaccines for the VRC against infectious
disease targets including Ebola, severe acute respiratory syndrome (SARS), and
West Nile virus, all of which have advanced into Phase 1 clinical trials over
the past three years.

    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 has developed 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 serve 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 VRC and the NIH Clinical Center will
complete the trial as planned; whether the HIV vaccine or any other product
candidates will be shown to be safe and effective in clinical trials; the
timing, nature and cost of clinical trials; 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.



    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-                             08/22/2006
    /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:  California
IN:  HEA MTC BIO
SU:  TRI

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