Nearly 30 years have passed since scientists discovered HIV, and yet no vaccine exists to fight the disease, for one very simple reason, says Not Exactly Rocket Science's Ed Yong — "HIV out-evolves us." HIV can produce about 100 billion new virus particles a day, and does so sloppily, copying itself with errors and creating a host of genetically variable viruses, Yong says. In the face of this evolutionary mechanism, vaccines and drugs quickly become obsolete. To tackle this problem, researchers have been looking into conserved regions of HIV proteins that when mutated tend to compromise the virus's ability to replicate. But, the virus has found a way around that as well, altering a different part of the protein to circumvent the conserved sites, Yong says. Enter a team of MIT researchers whose work recently published in PNAS may serve to outsmart HIV. "They have identified large groups of conserved sites on HIV proteins, which they call 'HIV sectors'. These aren't just sites that stay the same; they stay the same en masse while the rest of the virus warps around them," Yong says. "[The team's] idea is to train the immune system to attack all of the sites in a sector. To escape these "multiple points of immune pressure", HIV would have to develop many different mutations that, together, would almost certainly cripple it." In effect, Yong adds, the researchers are using HIV's rapid evolution against it by "herding it into an evolutionary dead end."
Jun 21, 2011