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 True, the news hit hard last month that the so-called "Boston
patients" — two men who received bone marrow transplants that
appeared to rid them completely of the AIDS-causing virus — had
relapsed and gone back onto antiretroviral treatment.
But experts say the disappointment could lay the basis for important
leaps forward in the search for a cure.
"It's a setback for the patients, of course, but an advance for the
field because the field has now gained a lot more knowledge," said
Steven Deeks, a professor and HIV expert at the University of
California, San Francisco.
He and other experts say the primary practical message is that
current tests designed to detect even very low levels of HIV present
in the body are simply not sensitive enough.
As well as having the human immunodeficiency virus (HIV), the Boston
patients both also had a type of blood cancer called lymphoma, for
which they were treated using bone marrow transplants — one man in
2008 and the other in 2010.
They continued taking the antiretroviral AIDS drugs, but eight
months after each patient's transplant, doctors found they could not
detect any sign of HIV in their blood.
In the early part of 2013, both patients decided to stop taking
their AIDS drugs and both appeared to remain HIV-free — prompting
their doctors, Timothy Henrich and Daniel Kuritzkes from Boston's
Brigham and Women's Hospital, to announce at a conference in July
that they may have been cured.
Yet in December came news that one of the men had begun to show
signs of an HIV rebound by August, while the second patient had a
relapse in November.
Henrich said the virus' comeback underlined how ingenious HIV can be
in finding hiding places in the body to evade attack efforts by the
immune system and by drug treatment.
"Through this research we have discovered the HIV reservoir is
deeper and more persistent than previously known and that our
current standards of probing for HIV may not be sufficient," he
said, adding that both patients were "currently in good health" and
back on antiretroviral therapy.
INSPIRATION
Barely a decade ago, few HIV scientists would have dared put the
words HIV and cure in the same sentence. Yet some intriguing and
inspiring cases in recent years mean many now believe it is just a
question of time before a cure is found.
First was the now famous case of Timothy Ray Brown, the so-called
"Berlin patient," whose HIV was eradicated by a complex treatment
for leukemia in 2007 involving the destruction of his immune system
and a stem cell transplant from a donor with a rare genetic mutation
that resists HIV infection.
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Such an elaborate, expensive and life-threatening procedure could
never be used as a broad-spectrum approach for the world's 34
million HIV patients. But the results in Brown focused scientific
attention on a genetic mutation known as 'CCR5 delta 32' as a target
for possible gene therapy treatment.
Then last March, French scientists who followed 14 HIV-positive
people known as the "Visconti patients", who were treated very
swiftly with HIV drugs but then stopped treatment, said that even
after seven years off therapy, they were still showing no signs of
the virus rebounding.
That announcement came only weeks after news of the "functional
cure" of an HIV-positive baby in Mississippi who received
antiretroviral treatment for 18 months from the day she was born. By
the time she was two this appeared to have stopped the virus
replicating and spreading.
A "functional cure" is when HIV is reduced to such low levels that
it is kept at bay even without treatment, though the virus can still
be detected in the body.
Sharon Lewin, an HIV expert at Monash University in Australia, said
all these developments, as well as the setback suffered by the
Boston patients, inspired scientists to investigate many different
approaches in the search for a cure.
"We've learnt many things here — and one of the most important is
that a tiny, tiny amount of virus can get the whole thing going
again," she told Reuters. "It's a clear message that we need better
ways to pick up the virus."
Scientists are now more convinced than ever that a two-pronged
approach which aims to firmly suppress the virus while bolstering
the immune system provides the best way forward.
"We need to attack in two ways — reduce the virus to very low levels
and also to boost the immune response. We can't do one without the
other," said Lewin.
"So we still have to think of other creative ways to control HIV.
And it's still early days... before we can say which approach is
likely to be the winner."
(Reporting by Kate Kelland; editing by Gareth Jones)
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