HIV infects women through healthy tissue â€" study
Dec 21, 2008
INSTEAD of infiltrating cuts in the skin, HIV appears to attack normal, healthy genital tissue in women, US. researchers said recently.
INSTEAD of infiltrating cuts in the skin, HIV appears to attack normal, healthy genital tissue in women, US. researchers said recently.
The researchers had assumed HIV used breaks in the skin such as herpes sores, to gain access to immune system cells.
Some had even thought the normal lining of the vaginal tract offered a barrier to invasion by the virus during sexual intercourse.
“Normal skin is vulnerable,†Thomas Hope of Northwestern University’s Feinberg School of Medicine said. He said until now, scientists had little understanding of the details of how HIV is transmitted sexually in women.
Hope and colleagues at Northwestern in Chicago and Tulane University in New Orleans developed a new method for seeing the virus at work.
They studied newly removed vaginal tissue taken from hysterectomies (surgery to remove the uterus) and introduced the virus which carried fluorescent, light-activated tracers.
They watched under a microscope as the virus penetrated the outer lining of the female genital tract. They also observed the same process in primates.
In both cases, they found HIV was able to quickly move past the genital skin barrier to reach immune cells.
Hope said the study suggests the virus takes aim at places in the skin that had recently shed skin cells. The finding casts doubt on the prior theory of the virus requiring a break in the skin or gaining access through a layer of skin cells in the cervical canal.
It might explain why some prevention efforts have failed. Hope said a clinical trial in Africa in which women used a diaphragm had no effect in reducing transmission of the virus.
Nor have studies of drugs designed to prevent wounds in genital herpes proven effective.
Hope said the findings emphasise the need for a vaccine to prevent infection. It also makes clear the need for the use of condoms. “People need to remember that they are vulnerable. If they just used a condom, we would not have this problem,†he said.
In the US, HIV is mostly transmitted among men who have sex with men. Globally, it is more commonly spread through heterosexual sex. The virus has infected 33 million people globally and has killed 25 million.
The researchers had assumed HIV used breaks in the skin such as herpes sores, to gain access to immune system cells.
Some had even thought the normal lining of the vaginal tract offered a barrier to invasion by the virus during sexual intercourse.
“Normal skin is vulnerable,†Thomas Hope of Northwestern University’s Feinberg School of Medicine said. He said until now, scientists had little understanding of the details of how HIV is transmitted sexually in women.
Hope and colleagues at Northwestern in Chicago and Tulane University in New Orleans developed a new method for seeing the virus at work.
They studied newly removed vaginal tissue taken from hysterectomies (surgery to remove the uterus) and introduced the virus which carried fluorescent, light-activated tracers.
They watched under a microscope as the virus penetrated the outer lining of the female genital tract. They also observed the same process in primates.
In both cases, they found HIV was able to quickly move past the genital skin barrier to reach immune cells.
Hope said the study suggests the virus takes aim at places in the skin that had recently shed skin cells. The finding casts doubt on the prior theory of the virus requiring a break in the skin or gaining access through a layer of skin cells in the cervical canal.
It might explain why some prevention efforts have failed. Hope said a clinical trial in Africa in which women used a diaphragm had no effect in reducing transmission of the virus.
Nor have studies of drugs designed to prevent wounds in genital herpes proven effective.
Hope said the findings emphasise the need for a vaccine to prevent infection. It also makes clear the need for the use of condoms. “People need to remember that they are vulnerable. If they just used a condom, we would not have this problem,†he said.
In the US, HIV is mostly transmitted among men who have sex with men. Globally, it is more commonly spread through heterosexual sex. The virus has infected 33 million people globally and has killed 25 million.