Researchers announced the creation of a drug candidate that is so powerful it could be used in an HIV "vaccine."
The groundbreaking drug candidate proved to block every strain of HIV-1, HIV-2 and SIV (simian immunodeficiency virus) that researchers isolated from humans or monkeys, the Scripps Research Institute reported. It also protects against new infections for up to eight months after the time of injection.
"Our compound is the broadest and most potent entry inhibitor described so far," said Michael Farzan, a professor on TSRI's Florida campus who led the effort. "Unlike antibodies, which fail to neutralize a large fraction of HIV-1 strains, our protein has been effective against all strains tested, raising the possibility it could offer an effective HIV vaccine alternative."
The development of the potentially life-saving drug was based on previous discoveries by the Farzan laboratory that showed the co-receptor CCR5 contains unique modifications in its HIV-binding region, and proteins based on this region can help fight off the virus. Using these findings, the researchers developed a drug candidate that binds to two sites on the surface of the virus simultaneously, blocking the HIV virus from entering.
"When antibodies try to mimic the receptor, they touch a lot of other parts of the viral envelope that HIV can change with ease," said TSRI Research Associate Matthew Gardner, the first author of the study with Lisa M. Kattenhorn of Harvard Medical School. "We've developed a direct mimic of the receptors without providing many avenues that the virus can use to escape, so we catch every virus thus far."
The team also created a delivery vehicle in the form of an engineered adeno-associated virus, which does not cause disease.
"This is the culmination of more than a decade's worth of work on the biochemistry of how HIV enters cells," Farzan said. "When we did our original work on CCR5, people thought it was interesting, but no one saw the therapeutic potential. That potential is starting to be realized."
The findings were published in a recent edition of the journal Nature.
