About 35 million people currently
have HIV and Aids has killed around
40 million people since it began
spreading 30 years ago.
...............................
London - Rapid evolution of HIV,
the human immunodeficiency virus,
is slowing its ability to cause Aids,
according to a study of more than 2
000 women in Africa.
Scientists said the research suggests
a less virulent HIV could be one of
several factors contributing to a
turning of the deadly pandemic,
eventually leading to the end of
Aids.
“Overall we are bringing down the
ability of HIV to cause Aids so
quickly,” Philip Goulder, a professor
at Oxford University who led the
study, said in a telephone interview.
“But it would be overstating it to say
HIV has lost its potency - it's still a
virus you wouldn't want to have.”
Some 35 million people currently
have HIV and Aids has killed around
40 million people since it began
spreading 30 years ago.
But campaigners noted on Monday
that for the first time in the
epidemic's history, the annual
number of new HIV infections is
lower than the number of HIV
positive people being added to those
receiving treatment, meaning a
crucial tipping point has been
reached in reducing deaths from
Aids.
Goulder's team conducted their
study in Botswana and South Africa -
two countries badly hit by Aids -
where they enrolled more than 2 000
women with HIV.
First they looked at whether the
interaction between the body's
natural immune response and HIV
leads to the virus becoming less
virulent or able to cause disease.
Previous research on HIV has shown
that people with a gene known as
HLA-B*57 can benefit from a
protective effect against HIV and
progress more slowly than usual to
Aids.
The scientists found that in
Botswana, HIV has evolved to adapt
to HLA-B*57 more than in South
Africa, so patients no longer
benefited from the protective effect.
But they also found the cost of this
adaptation for HIV is a reduced
ability to replicate - making it less
virulent.
The scientists then analysed the
impact on HIV virulence of the wide
use of Aids drugs. Using a
mathematical model, they found that
treating the sickest HIV patients -
whose immune systems have been
weakened by the infection -
accelerates the evolution of variants
of HIV with a weaker ability to
replicate.
“HIV adaptation to the most effective
immune responses we can make
against it comes at a significant cost
to its ability to replicate,” Goulder
said. “Anything we can do to
increase the pressure on HIV in this
way may allow scientists to reduce
the destructive power of HIV over
time.”
The study was published on Monday
in the journal Proceedings of the
National Academy of Sciences (PNAS)
. - Reuters
www.iol.co.za/scitech/science/news/evolution-of-hiv-slowing-ability-to-cause-aids-1.1789242