Scientists have
developed a test sensitive enough to identify HIV lurking in a dormant state in
the body. It appears to be faster and less invasive that the method used
currently to track down 'hidden' HIV – and as such represents an important step
in the direction of a potential cure.In recent decades,
the life expectancyof HIV-infected
patients has greatly improved thanks to antiretroviral therapy
(ART), a combination of medicines which slow down the rate at which the virus
is multiplying in the body.
Along with robust
preventive measures, ART has been instrumental in saving the lives of around
7.8 million people around the world in the last 15 years. ART suppresses the
HIV infection to almost undetectable levels.
However, if people
stop taking the drugs, the virus can re-emerge. Dormant versions of the virus
indeed hide in cellular reservoirs, ready to start replicating as
soon as patients discontinue treatment.
This
is one of the most important challenges to efficiently treating HIV-infected
individuals today to finding a cure.
In
a study now published in the journal Nature Medicine,
scientists describe a new test which allowed them to identify the virus hiding
in the body, and to assess if the detected virus could start replicating again
if patients stopped taking their drugs.
Today,
clinicians use a test known as "quantitative viral outgrowth assay",
or Q-VOA to do this. But they are confronted with a number a problems, in
particular the fact that it only provides a minimal estimate of the size of the
latent HIV reservoir. In addition, it is not very comfortable for patients as
it requires a large volume of blood, and it is labour-intensive, time-consuming
and expensive.
The
test presented in this latest research is called TZA. It works by detecting a
gene that is turned on in patients only when replicating HIV is present. The
gene thus acts as a marker for scientists to identify and then quantify the
virus.
The
test also addresses all previous concerns raised by Q-VOA, as it is much
cheaper, requires less blood from patients and can provide results in one week.
It could thus represents a very useful tool for clinicians in the near future.
Nevertheless,
the researchers believe that using Q-VOA will still could prove useful as the scientific community continues
to look for a cure.
"Using
this test, we demonstrated that asymptomatic patients on ART carry a much
larger HIV reservoir than previous estimates - as much as 70 times what the
Q-VOA test was detecting," said senior author Phalguni Gupta, professor
and vice chair of Pitt Public Health's department of infectious diseases and
microbiology, in a statement.
"Because
these tests have different ways to measure HIV that is capable of replicating,
it is likely beneficial to have both available as scientists strive toward a
cure."
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