The hopes of controlling the spread of HIV have been dealt another blow today when VaxGen of Brisbane, California, announced that its vaccine candidate failed in a large study among Thai heroin users. It is the second time that the vaccine, a genetically modified version of the gp0 surface protein of HIV, has shown ineffective.
The placebo-controlled study of 2546 Injecting drug users have found that HIV has infected 106 people who received the vaccine, a genetically engineered version of the HIV gp0 surface protein. The virus has infected 105 people who received dummy shots fire. Led by Bangkok Vaccine Evaluation Group of Thailand, the study involved scientists from VaxGen and the US Centers for Disease Control and Prevention.
The gp0 vaccine has a long and controversial history. The National Institute of Allergy and Infectious Diseases (NIAID) once defended the concept, partly because the researchers showed that antibodies in vaccinated individuals could "neutralize" HIV in test tube studies. But studies in 1993 showed that the antibodies triggered by the vaccine or immunogenic, constantly spirited strains of virus isolated directly from patients. Genentech, the original manufacturer of the vaccine, abandoned, which led epidemiologist Donald Francis leaves Genentech and co-found VaxGen.
In February, VaxGen reported the results of its first study of large-scale efficacy, which involved mainly gay men. The vaccine failed overall, but analysis suggested that gp0 might have worked in the few blacks and Asians in the study. The results were immediately challenged by some scientists ( Science NOW, February 27). VaxGen NIAID urged to follow up the results of the subgroup, but there is no intention to do so, said NIAID Director Anthony Fauci, who called today's results "not surprising at all."
The new findings do not mean gp0 is complete. A new study of 16,000 people just started in Thailand, which plans to use the protein as a wakeup call to any vaccine against AIDS that contains multiple HIV genes stitched into harmless canarypox. NIAID plans to provide significant funding for this study. Fauci said that the current negative results do not influence this decision: "As a boost, it could be qualitatively very different," said Fauci
Other AIDS researchers disagree .. "I think including gp0 is a waste of time, "said Dennis Burton, who studies antibodies against HIV in the Scripps research Institute in La Jolla, California. "It is bad immunogenic, and you can not get around that."
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