HIV Vaccine still a Fantasy? Research continues

FEARS that HIV vaccines may encourage infection with the virus have largely been laid to rest. This could revive the search for a vaccine.

In September 2007, pharmaceutical company Merck halted its STEP trial of an HIV vaccine because it appeared to work no better than a placebo.

The Cold Virus

Then it emerged that recipients of the vaccine who had previously caught the cold virus were more likely than those who hadn't to be infected with HIV, sparking fears that the vaccine made HIV infection more likely.

Loaded with HIV Genes

The vaccine consisted of a deactivated cold virus loaded with three HIV genes that were supposed to stimulate immunity. The fear was that participants with immune systems primed to fight the cold virus produced a surge of CD4 cells following injection with the vaccine, and that these cells provided ideal targets for HIV if the recipient was subsequently infected by the virus. "The vaccine may have added fuel to the fire," says Dan Barouch of the Beth Israel Deaconess Medical Center in Boston.

It Didn't Provoke Strong Immunity

Neither research team can explain why people with the cold virus antibodies were more likely to be infected with HIV. But Adrian Hill, a virologist at the University of Oxford, thinks this arose by chance, and that the vaccine failed simply because it didn't provoke strong enough immunity to HIV. The work should ease fears over other HIV vaccines, says Barouch.