In what throws more light on the mechanism of transmission of the HIV, city scientists have found that the presence of a specific protein in a woman's vaginal cells makes her more vulnerable to contracting the virus during sexual intercourse.
A three-member team from the National Institute for Research in Reproductive Health (NIRRH), Parel, has identified a protein - human mannose receptor - which if present in a woman's vaginal epithelial cells binds with the virus before it enters the blood stream.
"Our study has established that HIV binds to the receptor on the vaginal epithelial cells during intercourse and disturbs the surface of the cells. The virus then enters the cells after which the infection is transmitted in the body," said Dr AH Bandivdekar, who heads the research.
The study findings were published on November 22 in the Public Library Of Science, a peer-reviewed American journal.
It is a well-established fact that these receptors are present on the surface of the sperm and transmit the infection via women during intercourse by entering the penis.
"We have not yet studied why some women or men have lesser human mannose receptors," said Bandivdekar.
The team is now working on developing a drug that will prevent the receptor and the HIV from binding with each other.
The study has found that the presence of the receptors increases during ovulation, thereby increasing the risk during that period.
Till date, research has established that the virus binds with the CD4 protein - found in the blood cells - which leads to the transmission of the virus. "But sperms and vaginal cells don't have CD4 receptors so there was no clarity on how the virus enters the body via sexual transmission. Our study has shed light on this missing link," said Dr Bandivdekar.
"The study has revealed a new mechanism of transmission of HIV independent of the CD4 receptor. The findings bring hope that by blocking this receptor, one can prevent male-to-female sexual transmission of HIV," said Dr Preeti Mehta, head of department, microbiology, KEM Hospital.