AIDS is a notorious infection
that currently does not have a cure. Attempts
have been made in last 30 years to develop an effective vaccine to protect
against the infection caused by the HIV virus.
A research was conducted by Barton Haynes et al to
study the mechanisms behind the effectiveness of an HIV vaccine. The study was
published in The New England Journal of Medicine. The study was conducted in
Thailand in people receiving an experimental vaccine for HIV.
More than 16,000 adult volunteers were involved in the
RV144 trial. Those receiving the HIV vaccine had 31 percent less chances of
being infected with HIV as compared to those receiving placebo, but the reason
for the effect was not known.
To understand this issue and to predict which people could
possibly get infected, researchers analyzed the blood samples from a subset of
participants: 41 of them were vaccinated but later became infected with HIV and
205 participants remain unaffected after vaccination.
The study found that those individuals in whom there was
increased binding of the IgG immunoglobulin to a particular part of the HIV
viral envelope called the first and second variable regions or V1V2 were well
protected against HIV infection.
This binding might play a
significant role in protecting the human cells from infection.
On the other hand, those individuals who showed a high
binding of the IgA antibody to the first constant region or C1 region of the
viral envelope showed less protection from the HIV virus. It was suggested that
these antibodies may mitigate the protective effect of other protective
The study thus explains the possible immune mechanisms
responsible for the benefit of the HIV vaccine used in the RV1444 trial in
preventing HIV. The study may serve as a guide to the development of an
efficacious vaccine for HIV in the future.
1. Immune-Correlates Analysis of an HIV-1 Vaccine Efficacy Trial;
Barton Haynes et al; N Engl J Med 2012; 366:1275-1286 April