Wall Street Journal - January 5, 2012
The quest for a vaccine against AIDS is gaining momentum, with
research published Wednesday identifying promising new candidates
that protected monkeys against a powerful strain of the virus and
that soon could be tested in humans.
The study, published in the online edition of the journal Nature,
also shed light on how the first human vaccine to have conferred
limited protection against the AIDS virus may have worked.
In the research, several experimental vaccines partially
prevented infection in monkeys from a highly potent, highly
immune-resistant strain of simian immunodeficiency virus, an
unusual finding, researchers said. SIV is similar to human
immunodeficiency virus, or HIV, the virus that causes AIDS, and
SIV infection in monkeys resembles HIV infection in humans.
The new vaccines, combining two different technologies to
generate an immune response, reduced the chances that a monkey
would be infected by the virulent SIV strain in each exposure by
80% to 83%, compared with a placebo. The vaccines also
significantly reduced the amount of virus in the blood of monkeys
who did become infected.
The protection was only partial - most of the vaccinated monkeys
eventually became infected after multiple exposures. Still, the
study was among the first to prevent infection against a
virulent, highly immune-resistant SIV strain.
Plans are under way for clinical trials of a human-adapted
version of one of the vaccines used in the monkeys, said Dan
Barouch, professor of medicine at Harvard Medical School and Beth
Israel Deaconess Medical Center, and lead author of the study.
The vaccine will be tested in people both in the U.S. and
internationally, including in populations in Africa where HIV
infection rates are high, he said.
"There's more hope than ever before that an AIDS vaccine might be
possible," said Dr. Barouch.
The findings are part of a renaissance in AIDS research, with
multiple vaccine candidates under exploration and a landmark
study published last year showing that AIDS drugs can reduce the
spread of HIV from an infected person to others. But HIV
researchers still don't fully understand how to prevent
Vaccines, which work by spurring the body's ability to produce
antibodies or immune cells, are considered the holy grail of AIDS
research, because of the powerful role they played in eradicating
smallpox and eliminating or sharply reducing the spread of other
About 34 million people globally are infected with HIV, with
about 2.7 million more infected each year, according to United
In 2009, results of the first HIV vaccine to confer any
protection against HIV were announced, after a large clinical
trial in Thailand. That vaccine reduced the chances of infection
only 31%, and prompted some controversy when one analysis found
the results weren't statistically significant.
Still, the results helped rejuvenate the field. The latest study
helps explain what many scientists suspected after the Thai
trial: that the surface protein of the HIV virus, or its
envelope, is involved in preventing infection.
"It clearly demonstrated you need to make antibodies against the
outer coating of the virus," said Anthony Fauci, director of the
National Institute of Allergy and Infectious Diseases, the part
of the National Institutes of Health that oversees AIDS research
and co-funded the latest study.
"It confirms what was seen in the Thai trial was real," said
Louis Picker, associate director of the Vaccine and Gene Therapy
Institute at Oregon Health & Science University, who reviewed the
study led by Dr. Barouch but wasn't involved in it.
One strength of the study, said Dr. Fauci, was that the
researchers made their vaccines with one strain of SIV and
infected monkeys with another - replicating a likely real-world
scenario, because the ever-mutating AIDS virus comes in many
Many previous studies have used the same virus, but "that's not
the way the real world works," he said. "There are so many
different varieties of HIV out there. You've got to protect the
person against potentially any strain."
While monkey models are considered highly reliable in HIV
research and the findings resemble those of the Thai trial in
humans, HIV researchers cautioned that it won't be known whether
these vaccines work in humans until they are tried.
"HIV is progressively revealing its secrets and each time it gets
us closer to the goal, but this isn't like a basketball game
where it's the last two minutes," said Bruce Walker, a veteran
HIV researcher and director of the Ragon Institute, an enterprise
of Massachusetts General Hospital, the Massachusetts Institute of
Technology and Harvard University. Ragon Institute helped fund
the latest study and has raised $11 million of about $22 million
needed for the clinical trials, Dr. Walker said.
Mark Schwartz, chairman and founding partner of MissionPoint
Capital Partners, a private equity firm, donated $1 million of
his own funds, together with his wife Lisa, toward the clinical
trials. "Is it risky in a venture capital kind of way? Yes, it
is," he said. But, he said," Ultimately, we think the real payoff
is going to be in a vaccine."
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