Experimental Therapeutic Vaccine ‘Sharply Reduced’ Amount of HIV-Related Virus in Monkeys’ Blood

An experimental therapeutic vaccine for SIV -- the form of HIV that affects monkeys -- "sharply reduced but did not eliminate" the virus in monkeys' blood, according to a study published today in the online version of Nature Medicine, the AP/Boston Globe reports. According to researcher Wei Lu of Rene Descartes University in Paris, who led the study, evidence of SIV in macaques monkeys' blood cells fell 50-fold and evidence of the virus in blood plasma dropped 1,000-fold. The findings are based on a 10-month study of 10 SIV-positive animals that were given five injections over two months of a vaccine made from dendritic cells, which had been exposed to "chemically inactivated SIV," the AP/Globe reports. The results "suggest that immunotherapy may indeed be a realistic goal," Nina Bhardwaj of New York University and Bruce Walker of Partners AIDS Research Center at Massachusetts General Hospital said an accompanying commentary. However, they said "questions" about the type of monkeys vaccinated and "some other aspects" of the study "must temper enthusiasm until the results can be confirmed" (Schmid, AP/Boston Globe, 12/23). One potential problem is viral gene mutation that occurred in a similar study conducted at Harvard University in January. In that study, a single gene mutation in the virus changed the shape of the epitope, making it unrecognizable to CD4+ T cells and causing the vaccine to fail in one monkey. All of the virus in the monkey mutated within six weeks, and the monkey soon became ill and died (Kaiser Daily HIV/AIDS Report, 1/17). Lu acknowledged that the issue "raised by Harvard researchers is a very serious one" (AP/Boston Globe, 12/23).

'Anticipation' Surrounds Results of VaxGen's HIV Vaccine Trial
In related news, the Boston Globe today examines the "much anticipated" results of VaxGen's first human trial of an HIV vaccine, a 5,400-patient, $200 million project that has spanned more than 10 years. After Dec. 31, researchers will begin examining whether the vaccine candidate AIDSVAX was effective in protecting against HIV infection, and VaxGen officials have "promise[d]" to release information about the effectiveness of the vaccine by March, an announcement "certain to generate enormous attention," the Globe reports. Half of the participants in the trial -- 5,100 homosexual men and 300 women with multiple sex partners -- received the vaccine, and half received a placebo, which was injected by doctors in "hundreds" of locations in North America, according to the Globe. In addition, VaxGen later this year is expected to announce the results of a trial of the vaccine that included 2,400 injection drug users in Thailand. The FDA has already fast-tracked the review process for AIDSVAX (Mishra, Boston Globe, 12/23).