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"AIDS
virus losing virulence, says scientific report"
The
Star (www.thestar.com.my)
(30/09/05)
LONDON: The human immunodeficiency virus (HIV) that causes AIDS appears to
have weakened since the start of the pandemic more than two decades ago,
according to a Belgian study published yesterday in the journal AIDS.
Scientists at Antwerp's Institute of Tropical Medicine compared HIV-1
samples from 1986-89 and 2002-03, and found 75% of the newer samples were
weaker, both in terms of spread within individuals and transmission to
others.
Of the two types of HIV that infect humans, HIV-1 is more virulent than
HIV-2.
AIDS has killed more than 20 million people since 1981.
“This study provides the first experimental evidence suggestive for HIV-1
attenuation over time” and is “crucial in our thinking on HIV-evolution in
the epidemic,” said Kevin Arien, a former member of the Antwerp institute's
Microbiology, HIV and Retrovirology Research Unit, who compiled the report.
Six scientists selected 24 patient samples from the Institute of Tropical
Medicine, 12 from 1986-89 and 12 from 2002-03. Twelve samples came from
patients in early stages of the disease and 12 others were isolated from
patients in advanced stages, according to the study published in the
Swiss-based International AIDS Society journal.
They conducted laboratory experiments in which 12 matched pairs of old HIV-1
and new HIV-1 viruses were allowed to infect and replicate in cocktails of
human white blood cells, which are targets for HIV infection.
The two viruses competed with each other at infecting the cells, and in nine
out of 12 experiments, the old virus replicated more rapidly than the new,
the study showed.
“What we found most shocking is that HIV-1 has weakened as much as we
observed,” Eric Arts, of the Division of Infectious Diseases at Case Western
Reserve University in Cleveland, Ohio, said. “If you look at that
trajectory, HIV-1 may stop causing death in 60 years.”
Marco Vitoria, AIDS expert at the UN's World Health Organisation, criticised
the sample for being “very small,” in a written response to questions,
adding “attenuation isn't new in the natural history of many other
infectious diseases, and is a very slow process. — Bloomberg
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