Universal cure for HIV gets tougher

Washington: Researchers have claimed that the amount of potentially active, dormant forms of HIV hiding in infected immune T cells may actually be 60-fold greater than previously thought.

Just when some scientists were becoming more hopeful about finding a strategy to outwit HIV's ability to resist, evade and otherwise survive efforts to rid it from the body, another hurdle has emerged to foil their plans, new research from infectious disease experts at Johns Hopkins shows.

The researchers said that the hidden HIV is part of the so-called latent reservoir of functional proviruses that remains long after antiretroviral drug therapy has successfully brought viral replication to a standstill.

The study comes after a three-year series of lab experiments, which they say represents the most detailed and comprehensive analysis to date of the latent reservoir of HIV proviruses. If antiretroviral therapy is stopped or interrupted, some proviruses can reactivate, allowing HIV to make copies of itself and resume infection of other immune cells.

Study results showed that among 213 HIV proviruses isolated from the reservoirs of eight patients and initially unresponsive to highly potent biological stimuli, some 12 percent could later still become active, and were capable of replicating their genetic material and transmitting infection to other cells.

Senior study investigator Robert Siliciano said his team's latest study findings pose a serious problem to prevailing hopes for the so-called "shock and kill" approach to curing HIV.

That approach refers to forcing dormant proviruses to "turn back on," making them "visible" and vulnerable to the immune system's cytolytic "killer" T cells, and then eliminating every last infected cell from the body while antiretroviral drugs prevent any new cells from becoming infected.

Siliciano said this new discovery could boost support for alternative approaches to a cure, including renewed efforts to develop a therapeutic vaccine to stimulate immune system cells that attack and kill all HIV.

The study was published in journal Cell.