US Study: HIV Infects Women Through Healthy Tissue
http://www.truthout.org/121808WA
Chicago - Instead of infiltrating breaks in the skin, HIV appears
to attack normal, healthy genital tissue in women, U.S. researchers
said on Tuesday in a study that offers new insight into how the AIDS
virus spreads.
They said researchers had assumed the human immunodeficiency
virus, or HIV, sought out breaks in the skin, such as a herpes sore,
in order to gain access to immune system cells deeper in the tissue.
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 in a telephone
interview.
"It was previously thought there had to be a break in it
somehow,"
said Hope, who is presenting his findings at a meeting of the
American
Society for Cell Biology in San Francisco.
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
hysterectomy surgeries, 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, called the squamous epithelium.
They also observed the same process in nonhuman primates.
In both cases, they found HIV was able to quickly move past the
genital skin barrier to reach immune cells, which the virus targets.
Hope said the study suggests the virus takes aim at places in the
skin that had recently shed skin cells, in much the same way that
skin
on the body flakes off.
The finding casts doubt on the prior theory of the virus
requiring
a break in the skin or gaining access through a single layer of skin
cells that line the cervical canal.
And it might explain why some prevention efforts have failed.
Hope
said one clinical trial in Africa in which women used a diaphragm to
block the cervix had no effect at reducing transmission of the virus.
Nor have studies of drugs designed to prevent lesions in genital
herpes proven effective.
Hope said the findings emphasize the need for treatments such as
a
vaccine to prevent infection.
And it makes clear the need for the use of condoms, which are
highly effective at preventing infection.
"People need to remember that they are vulnerable," Hope said.
"The sad part is if people just used a condom, we wouldn't have this
problem."
In the United States, HIV is mostly passed among men who have sex
with men. Females account for 26 percent of all new HIV cases in the
United States, according to the U.S. Centers for Disease Control and
Prevention.
Globally, HIV is more commonly spread by heterosexual sex. The
virus has infected 33 million people globally and has killed 25
million.
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