PET scan reveals hiding places of HIV

18 March 2015
An HIV ribbon

Newly developed scanning techniques make it possible to identify where latent HIV is hiding in the body. This new development will create better opportunities to eradicate HIV from the body. Antiretroviral treatment (ART) is able to eradicate HIV from the blood, but as the virus returns when people stop taking treatment, HIV must be hiding somewhere in the body.

It is always assumed that HIV hides in immune cells at various ‘sanctuary sites’, where the virus either replicates very slowly or becomes completely dormant. One hypothetical treatment strategy based on this hypothesis is to wake up the virus that is hiding and then kill it, which is referred to as the “kick and kill” strategy. However, until recently it was always unknown where the main sanctuary sites are in the body and whether existing drugs can research these sites, making this strategy difficult to implement.

Researchers at the Emory University in Atlanta speculated whether a PET scan could show these sanctuary sides in the body, as PET scans are also able to show the spread of cancer in the body. The idea was prompted by the discovery of an antibody that binds strongly to SIV, the version of HIV that infects monkeys. To test the use of PET scanning, the research team injected radioactive antibodies into three monkeys infected with SIV and on antiretroviral treatment. The PET scan, which detects the location of the radiation sources, revealed radioactive antibodies bounded to the SIV virus in a range of sites including the nose, lungs, gut, genitals and lymph nodes in the armpits and groin. Antibodies were not found in the brain, although this is considered to be another sanctuary site.

Although this new technique does not show viruses that are completely latent, being able to see where there are low viral concentrations in the body is a major advance for the development of targeted treatment. The next step in this process is the development of antibodies that bind to proteins made by the HIV virus, to make it possible to identify the human sanctuary sites for HIV.

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