Researchers at the CNRS, Institut Curie and Institut Pasteur in Paris investigating how HIV avoids being destroyed by immune system cells have discovered that HIV alters the pH of the cellular compartments where it accumulates, thus preventing the activation of the very enzymes that would normally degrade it.
HIV attacks two sorts of white blood cells: macrophages, which play an early role in immune defense by engulfing and then digesting the invader, and CD4 T lymphocytes, which come into play later in the immune response. HIV accumulates in the infected macrophages, creating viral reservoirs that are inaccessible to current antiviral treatments.
The researchers have shown that the viral particles accumulate in certain compartments of the infected macrophages, which normally have an acid pH at which HIV would not survive. But pH measurements have revealed that HIV prevents the acidification of these compartments, creating an environment where it can survive and multiply.
This study sheds new light on how HIV remains infectious for long periods of time and cannot be eliminate completely by retroviral therapies, and points the way to the identification of new therapeutic targets for the elimination of viral stocks in macrophages.