March 26, 2004
In four cases, HIV was transmitted man-to-woman, and in four cases it was transmitted woman-to-man. Derdeyn and co-authors found that newly transmitted viruses were very different from those in people who had HIV for years. New infections showed only one variant of HIV, while long-term infections were marked with several variants. Moreover, the variants in new HIV infections seemed vulnerable.
"They were less shielded with the sugar substance that the virus uses to protect itself from ... antibodies," Derdeyn said, adding that the viruses were particularly vulnerable to antibodies in the blood of the transmitting partner. "So a seemingly vulnerable virus turns out to be the one that's the strongest in establishing new infections," Derdeyn noted.
Derdeyn said the discovery is good news for vaccine researchers because it gives them a window of opportunity and a target: single variants in new HIV infections. The findings suggest that low levels of antibodies created by vaccines, if properly targeted and timed, could stave off HIV infections. The research also contributes to the idea of creating prophylactic treatments for use just before or after possible HIV exposure, Derdeyn said.
03.26.04; Dave Parks