WASHINGTON — A new strain of the virus that causes AIDS has been
discovered in a woman from the African nation of Cameroon. It differs from the
three known strains of human immunodeficiency virus and appears to be closely
related to a form of simian virus recently discovered in wild gorillas,
researchers report in Monday's edition of the journal Nature Medicine.
The finding "highlights the continuing need to watch closely for the emergence
for new HIV variants, particularly in western central Africa," said the
researchers, led by Jean-Christophe Plantier of the University of Rouen, France.
The three previously known HIV strains are related to the simian virus that
occurs in chimpanzees.
The most likely explanation for the new find is gorilla-to-human transmission,
Plantier's team said. But they added they cannot rule out the possibility that
the new strain started in chimpanzees and moved into gorillas and then humans,
or moved directly from chimpanzees to both gorillas and humans.
The 62-year-old patient tested positive for HIV in 2004, shortly after moving to
Paris from Cameroon, according to the researchers. She had lived near Yaounde,
the capital of Cameroon, but said she had no contact with apes or bush meat, a
name often given to meat from wild animals in tropical countries.
The woman currently shows no signs of AIDS and remains untreated, though she
still carries the virus, the researchers said.
How widespread this strain is remains to be determined. Researchers said it
could be circulating unnoticed in Cameroon or elsewhere. The virus' rapid
replication indicates that it is adapted to human cells, the researchers
reported.
Their research was supported by the French Health Watch Institute, the French
National Agency for Research on AIDS and Viral Hepatitis and Rouen University
Hospital.
A separate paper, also in Nature Medicine, reports that people with genital
herpes remain at increased risk of HIV infection even after the herpes sores
have healed and the skin appears normal.
Researchers led by Drs. Lawrence Corey and Jia Zhu of the Fred Hutchinson Cancer
Research Center found that long after the areas where the herpes sores existed
seem to be clear, they still have immune-cell activity that can encourage HIV
infection.
Herpes is marked by recurring outbreaks and has been associated with higher
rates of infection with HIV. It had been thought that the breaks in the skin
were the reason for higher HIV rates, but a study last year found that treatment
of herpes with drugs did not reduce the HIV risk.
The researchers tested the skin of herpes patients for several weeks after their
sores had healed and found that, compared with other genital skin, from twice to
37 times more immune cells remained at the locations where the sores had been.
HIV targets immune cells and in laboratory tests the virus reproduced three to
five times faster in tissue from the healed sites as in tissue from other areas.
"Understanding that even treated (herpes) infections provide a cellular
environment conducive to HIV infection suggests new directions for HIV
prevention research," commented Dr. Anthony S. Fauci, director of the National
Institute of Allergy and Infectious Disease.
Source : National Institutes of Health and the Tietze Foundation.
