MEXICO;HIV vaccine puzzle grows even more complicated

Failure of a highly touted HIV vaccine in clincial trials in 2007 raised tough questions aobut the best approach to designing such a vaccine- and even about whether HIV vaccine research should continue.

At AIDS 2008, scientists from the Tulane National Primate Research Centre in the USA add a new turn to the vaccine maze with evidence that antibodies do not help control simian immunodeficiency virus (SIV) in monkeys.

African green monkeys do not get sick with AIDS diseases despite high and persistent SIV viral loads (the number of viral copies in a millilitre of plasma).

Many theorised that high SIV viral loads in monkeys reflect low antibody levels- and that the correlation implies a role for antibodies in controlling viral load. But research presented at AIDS 2008 in Mexico suggesst that monkeys stripped of antibodies by treatment with an anti-antibody agent had the same viral load and the same CD4 cell counts as monkeys with their antibody forces intact.

This presents researchers with yet another challenge in vaccine development.