New Delhi, Apr 27: The dreaded HIV appears to lose proteins during transmission from one person to another, becoming more vulnerable to attack of antibodies even as the finding may help in developing a vaccine against the killer virus, a study says. Scientists analysed HIV after it was transmitted from one partner to the other in eight couples and found that in six cases, transmitted viruses had distinctive surface proteins as compared to others, a report in the journal `Science' said.

The study was conducted by a team of scientists from the University of Alabama, Birmingham among over 100 couples in Zambia.

Each person infected with HIV harbours a swarm of slightly different versions of the virus. But when HIV passes from a mother to child or between sexual partners, only one of those strains in transmitted, the report said.

HIV establishes an infection by latching its surface protein, "gp120", onto surface molecules called "CD4" receptors found on immune cells of host, it said.

The team found that "gp120s" on the transmitted virus had been stripped of some amino acids (molecules that form proteins), the report said, adding these scantily clad proteins find it easier to establish an infection as the region of surface protein that best binds to "CD4" is exposed.

Bureau Report