Potential New
Weapon in HIV Battle
An HIV vaccine developed by a
team of international researchers
has advanced further than any
other in years, raising hopes for
controlling the virus that can lead to AIDS.
Dan Barouch, an immunologist at Beth Israel
Deaconess Medical Center and Harvard Medical
School, leads the team that created the vaccine,
called mosaic Ad26/ENV, or Ad26 for short.
In July, a paper in the British medical journal
The Lancet detailed the first human trials of Ad26,
conducted in Africa, Thailand and the United
States. Most of the 393 adults in the trials showed
strengthened immune responses, and side effects
were minimal. The vaccine also protected 67 percent
of rhesus monkeys exposed to a simian virus similar
to HIV, according to the researchers.
Ad26 is currently in an efficacy trial involving
2,600 people in Africa; the trial will determine if the
vaccine can actually protect people from the virus.
Only four other potential HIV vaccines have made it
to this stage of development. The last one, tested in
2013 in the U.S., was shelved due to a lack of results.
Results of the Ad26 trial are expected in three years.
Barouch talked to Discover about how the vaccine
works and its potential.Q
What’s the biggest challenge to creating
an HIV vaccine?A
HIV is a virus of extraordinary diversity. There are
different genetic sequences of HIV throughout the
world, within each country and even within every HIV-
infected individual.Q
How do you address HIV’s diversity?A
Our approach to that question, and not saying it’s
a complete answer but at least a step in the right
direction, is a so-called mosaic antigen. What that means
is that the HIV sequences that are put into the vaccine are
not from any single strain that was found in a virus from
an individual. But rather, [the vaccine] is a collage of virus
strains that aims to provide the best immune responses to
combat the genetic diversity of HIV worldwide.Q
How well does it work?A
Animal data and the early phase human data look
promising and have warranted the advancement of this
vaccine into a large-scale human trial to test whether or not
it will prevent HIV infection in humans.
It’s definitely a step in the right direction, and it’s a novel
approach to try and address the question of global virus
diversity. Is it good enough? We will only know that when
we see the results of the efficacy trial.
If successful, it could have an incredibly important
health effect in curbing and ultimately controlling
the HIV epidemic.Q
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62 DISCOVERMAGAZINE.COM
M. SCOTT BRAUERMEDICINE
Dan Barouch