| ■ HIV Vaccine May Have Increased Infection Risk: Report | 2008.11.11 |
| Clinical trials of a seemingly promising HIV vaccine were halted in 2007 because the vaccine may actually have increased the risk of infection, according to a study by researchers at the Montpellier Institute of Molecular Genetics in France. The problem with Merck & Co.'s HIV-1 vaccine was discovered during second stage trials, Agence France Presse reported. The vaccine used a modified form of the common Adenovirus 5 (Ad5) cold virus to carry elements of HIV, which were meant to trigger the immune system to fight off HIV infection. However, more of the vaccine recipients who had prior immunity to the Ad5 virus were infected than clinical trial participants who didn't receive the vaccine. It's possible the presence of long-lasting antibodies generated to fight Ad5 when people caught a cold altered the body's response to the HIV-1 vaccine, the French researchers said, AFP reported. They noted that HIV infection spread through cell cultures three times faster when Ad5 antibodies were present. The study was published online in the Journal of Experimental Medicine. |