Scientists are reporting early but promising results from a new drug that blocks HIV as it attempts to invade human cells. The approach differs from most current antiretroviral therapy, which tries to limit the virus only after it has gained entry to cells. The medication, called VIR-576 for now, is still in the early phases of development. But researchers say that if it is successful, it might also circumvent the drug resistance that can undermine standard therapy, according to a report published Dec. 22 in Science Translational Medicine.
The new approach is an attractive one for a number of reasons, said Dr. Michael Horberg, director of HIV/AIDS for Kaiser Permanente in Santa Clara, Calif. "Theoretically it should have fewer side effects and there's probably less of a chance of mutation in developing resistance to medication," said Horberg, who was not involved in the study. Viruses replicate inside cells and scientists have long known that this is when they tend to mutate potentially developing new ways to resist drugs. "It's generally accepted that it's harder for a virus to mutate outside cell walls," Horberg explained.
The new drug focuses on HIV at this pre-invasion stage. "VIR-576 targets a part of the virus that is different from that targeted by all other HIV-1 inhibitors," explained study co-author Frank Kirchhoff, a professor at the Institute of Molecular Virology, University Hospital of Ulm in Ulm, Germany, who, along with several other researchers, holds a patent on the new medication. The target is the gp41 fusion peptide of HIV, the "sticky" end of the virus's outer membrane, which "shoots like a 'harpoon'" into the body's cells, the authors said. The launch of this peptide is a first step in the virus's bid to inhabit host cells.
