HIV spreads just like other viruses: It takes over a cell’s DNA and uses the cell’s infrastructure to make copies of itself. Most HIV treatments work by blocking new cells from getting infected.
The cells that are actively producing HIV are constantly being killed, either by HIV or by the immune system. So once you stop new cells from getting infected, the patient can achieve a viral load close to zero.
Viral reservoir remains hidden
That’s not a total cure though, because some HIV-infected cells go into a resting state, and stop actively producing the virus. This viral reservoir remains hidden from the immune system. The problem is that if treatment stops, the latent virus will eventually reactivate and the disease will be able to spread again.
Doctors have gotten pretty good at stopping HIV from infecting new cells, but they still haven’t figured out how to eliminate these reservoirs, and so patients must take medication for their entire life.
That’s why maintaining health care access for everyone living with HIV is a major public health challenge. And even for those who can access life-long care, over time these drugs can damage the liver, kidneys, heart and brain.
‘Shock and kill’
In 2012, a University of North Carolina research group published a proof of concept for a cure called “shock and kill.” They showed that a cancer drug called Vorinostat can “shock” some infected cells into producing HIV again. That brings the virus out of hiding so it can be “killed.”
They described their work in the Journal of Clinical Investigation. “What we did in this study was to determine the optimal dosing regimen — how often the drug should be given — in order to measure consistent reactivation of HIV,” co-author Nancie Archin said to VOA.
Once reactivated, those cells should self-destruct or be killed by the immune system, just like in a typical HIV treatment. But the UNC team’s findings confirm previous evidence showing that isn’t happening.
It’s not yet clear why that is.
One theory was that Vorinostat was weakening the immune system, so that it wasn’t able to kill the infected cells. But the report ruled that out — relevant parts of the immune system, the study found, were not weakened.