Functional HIV Cure Possible with Early Treatment

Early and effective HIV therapy may, in a small number of patients, lead to a functional cure of the disease, according to a new study.

Researchers at the Institut Pasteur (Paris, France) reviewed the French database of HIV patients from 1997 to 2011, finding 756 post-treatment HIV controllers (PTCs) who were treated within 6 months of infection and who maintained therapy for at least a year. Of those who had a detectable viral load before therapy and an undetectable one afterward, just 70 stopped treatment and had subsequent viral load measurements. The researchers then identified 10 men and 4 women PTCs that achieved control of infection through mechanisms that different from those commonly observed, and that their capacity to control is likely related to early therapeutic intervention.

All 14 PTCs were treated within the first two months of infection and had been off therapy for between 4 and 9.6 years; their plasma viral loads are below 40 copies of HIV RNA per milliliter in all but three cases, and below 5 copies in five patients. While all 14 still have HIV, in most cases it can only be detected with ultrasensitive laboratory tests and is undetectable by standard methods. The virus is conventionally regarded as "undetectable" if the plasma viral load is below 50 copies per milliliter, although single-copy assays—only rarely used outside the lab—can detect smaller amounts of HIV.

The researchers found that PTCs were able, after therapy interruption, to keep, and in some cases further reduce, a weak viral reservoir. The researchers speculated that this might be related to the low contribution of long-lived cells to the HIV-reservoir in these patients, and suggested limiting the pool of infected cells is crucial for the successful control of viral replication in the absence of therapy. The researchers calculated that the probability of maintaining viral control after a year was 15.3%, meaning that about 85% of patients treated early will still face viral rebound if they stop treatment. The study was published early online on March 14, 2013, in PLoS Pathogens.

“It shows there is some immune response that can be stimulated not just to control infection but to prevent infection if that part of the immune system can be primed and activated,” concluded lead author Asier Sáez-Cirión, PhD, and colleagues. “We estimated the probability of maintaining viral control at 24 months post-early treatment interruption to be about 15%, which is much higher than the one expected for spontaneous control.”

The study follows a report recently released at the annual Conference on Retroviruses and Opportunistic Infections (CROI), which was held during March 2013 in Atlanta (GA, USA), of what appears to be curative early treatment which completely eliminated HIV in a newborn using a combination of antiretroviral treatments in the first few hours of life.

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