Vaccine for AIDS may be a step closer Internet and LA times, July 9, 2010

10:53 09.07.2010

 An effective vaccine against the AIDS virus may have moved one step closer to reality.  Federal researchers have identified a pair of naturally occurring antibodies that are able to kill more than 90% of all strains of the AIDS virus, a finding that may lead to the development of new treatments for HIV infections and to the production of the first successful vaccine against the virus.   The data has shown that HIV-l the virus that causes AIDS, is notoriously mutable, changing the composition of proteins on the surface with ease to escape pressure from the immune system.  This enables it to continue infecting cells even after the appearance of antibodies targeting it--and to avoid the relatively ineffective vaccines developed so far.

There are hundreds of variants of the virus  now in circulation around the world, and the intensification of so called broadly neutralizing antibodies than can block the bulk of them has been the holy grail of HIV researchers .However to date the best antibodies that researchers have found block only 30=40% of all HIV strains.  The identification of antibodies than can block more than 90% of strains could lead to what some researcher are dubbing a renaissance in AIDS prevention and treatment. 

Nable and his colleagues isolated the antibodies from the blood of a 60 year old African American gay man.  Using newly developed imaging and analytical techniques they found that the two antibodies, called VRCO1 and VRC02 bind to a spike on the surface of the virus.  This spike interacts with the CD 4 binding site on the surface of CD 4 T cells.  With the binding the virus can't enter the cells, thus it is called an entry inhibitor.  The virus can only use the CD 4 receptor to enter cells and can’t tolerate mutations in the spike.  The composition of the spike is thus pretty much constant in all variants of HIV in circulation. 

The antibodies attach to a virtually unchanging part of the virus, and this explains why they can neutralize such an extraordinary range of HIV strains.  With the antibodies in hand, the team was able to determine precisely how the HIV spike and the antibodies interact.  They were then able to produce a synthetic version of the spike that could elicit the production of similar blocking antibodies in animal cells.  They are now testing the synthetic spike in a possible vaccine in animals and hope to expand to human testing in the relatively near future. The antibodies can also be reproduced by biotechnology and used as a treatment for someone who is already infected.  Researchers, who are already testing the antibodies in animals, hope that at the very least the antibodies wilt provide synergistic effects when used in conjunction with antiviral drugs.