- DENVER (AP) --Researchers have revealed they have found genetic material
from the AIDS virus still lurking in the semen cells of men whose use of
the AIDS drug cocktail had reduced the virus in their blood to undetectable
levels.
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- In a study to be released Friday, virologists
at Thomas Jefferson University in Philadelphia said that patients with
the HIV provirus -- the genetic component of the AIDS virus -- might still
be able to transmit the virus to others if they fail to practice safe sex.
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- In test-tube experiments, the scientists
were able to grow the AIDS virus when they combined tiny provirus samples
from the men with blood from individuals who had never been infected.
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- The researchers described these provirus
reservoirs as the "Trojan horse" of AIDS, and said they may lurk
in the brain and retina cells, too. Determining how to eradicate these
last traces is the "endgame" in the two-decade battle against
AIDs, they said.
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- The study will be presented Friday at
the annual infectious-diseases meeting being held in Denver.
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- "In many patients, we've gone 90
yards and we're at the point where we just have to push the ball over the
goal line," said doctor Roger J. Pomerantz, director of the Center
of Human Virology at Thomas Jefferson. "But those last 10 yards can
be very hard."
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- In a separate study, Brown University
researchers will report that combination drug therapy effectively lowers
viral levels in the genital tracts of HIV-infected women. This may reduce
the risk of transmitting the virus to adults during sex and to babies during
childbirth, said obstetrics researcher Dr. Susan Cu-Uvin.
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- However, Cu-Uvin said, up to 3 percent
of the women in the Brown study did not have detectable levels of HIV in
their blood but still had HIV traces in their genital fluids, indicating
the presence of provirus.
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- Other AIDS researchers agreed that these
reservoirs of dormant HIV probably represent the final barrier to curing
AIDS.
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- The first step, researchers said, is
determining precisely where the genetic traces of HIV are hiding.
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- A likely location, they said, is the
CD4 T cells. The cells function as the immune system's memory and are found
throughout the body. Up to 1 million of these cells appear to hang onto
the blueprint of HIV for as long as 10 years so the body will recognize
the infection and mount a defense if it appears again.
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- In the Philadelphia study, Pomerantz
sampled cells in the semen of seven men who had no detectable HIV freely
circulating in their blood or semen.
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- Pomerantz found provirus reservoirs locked
in cells of four of the men. The three other men could have provirus reservoirs
in cells located in other difficult-to-study crannies of the body, such
as the brain or the retina of the eye, he said.
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- "These are the patients who are
doing the best," Pomerantz said. "If it happens in them, it is
likely to be more common in the general HIV-infected community."
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- He recommended that these men continue
taking AIDS drugs and practice safe sex.
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- AIDS researchers are debating how to
best treat -- and perhaps cure -- these carriers.
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- Doctor Anthony Fauci, head of the National
Institute of Allergy and Infectious Diseases in Bethesda, Md., has attempted
to purge the infected memory cells by triggering them to spring to life
with hormones.
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- In theory, the activated memory cells
would release their virus and die. Antiviral drugs would catch the released
virus.
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- Another strategy is to give patients
higher doses of existing AIDS drugs or use more powerful ones still in
testing stages.
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