Researchers from the National
Institutes of Health (NIH) have found that a protein in seminal fluid speeds up
the spread of HIV in uterine tissue. The protein, called interleukin 7 (IL-7),
is from a family of proteins that regulate the immune response. IL-7 is found
in normal semen, but is found at high levels in the semen of men with HIV
infection.
The researchers created a culture
system of small pieces of cervical tissue and used it to simulate male-to
female HIV transmission. They then observed the spread of the virus to tissue
under controlled conditions at the laboratory. In tissue containing IL-7 at
levels found in the semen of HIV-infected men, the virus spread more quickly
than to tissue that was not treated with IL-7. The researchers suggest that
IL-7 alone or along with other molecules foster male-to-female HIV
transmission. Also, it is possible that the level of IL-7 in semen determines
how infectious a specific HIV-infected male is for a female partner.
HIV targets T cells, a type of
immune cell that helps organize the body’s defenses against disease-causing
organisms. The T cells die quickly when they are infected with HIV, before the
virus can produce a large number of copies of itself. The researchers found
that in isolated pieces of cervical tissue, HIV-infected T cells live longer in
the presence of IL-7 and continue to produce the virus. IL-7 also stimulated
uninfected T cells to divide, thus increasing their number. The new T cells are
additional targets for the virus to enable it to increase its spread.
Researchers believe that one day it may be possible to prevent or delay HIV
transmission by blocking seminal IL-7.The researchers said that they need
additional studies to confirm the observations.
The Friends of AIDS Foundation is
dedicated to enhancing the quality of life for HIV positive individuals and
empowering people to make healthy choices to prevent the spread of the HIV
virus. To learn more about The Friends of AIDS Foundation, please visit: http://www.friendsofaids.org.
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