amfAR, The Foundation for AIDS Research

Perfecting Tools to Monitor HIV Viral Loads

By Jeffrey Laurence, M.D.

Dr. Sarah Palmer, a scientist at the University of Sydney in Australia, (formerly at the Karolinska Institute in Stockholm, Sweden) and a member of amfAR’s ARCHE cure research consortium, recently reviewed the state of knowledge in the detection and monitoring of HIV levels in the blood of infected people. Writing in the March issue of Current Opinion in HIV and AIDS, she notes that current HIV treatment guidelines recommend starting antiretroviral therapy (ART) as soon as an HIV infection is recognized, regardless of CD4+ T-cell counts. This is coupled with careful monitoring of HIV RNA levels in the blood. The goal is to suppress virus to below the detection capacity of standard testsabout 50 virus copies per milliliter of bloodand to keep it there.

Dr. Palmer (center) and other members of amfAR’s ARCHE research consortium  

But Dr. Palmer goes on to emphasize that current anti-HIV drugs cannot eradicate the virus once a reservoir has been established. Strategies to achieve that goal—an HIV cure—are under way, led by many amfAR-funded scientists and other groups. But documentation of efficacy, or lack of it, in such clinical trials demands ultrasensitive virus detection methods. Dr. Palmer has been at the forefront of their development.

She notes that such assays, which can find a single copy of the virus in a milliliter (about a fifth of a teaspoon) of blood, can also be used to document viral “blips,” or transient, low-level bursts of virus. The significance of these blips to the durability of infection control in a given individual is currently under study. These methods will also enable researchers to define the source of persistent virus in people on long-term ART. Recently, Dr. Palmer and colleagues worldwide who are using the techniques she has developed, have been able to assess the efficacy of “shock” strategies by which latent HIV is chemically coaxed out of a person’s latently infected cells, rendering them vulnerable to attack by ART.

Dr. Laurence is amfAR’s senior scientific consultant.  

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