AIDS virus protein coat lethal.

AIDS virus protein coat lethal

The more scientists learn about the AIDS virus, the more diabolical the particle appears. A nongenetic component of the AIDS-producing human immunodeficiency virus (HIV) is sufficient to kill cells in vitro, several recent studies show. The new finding complicates the vaccine picture because the protein, if included in a vaccine, could harm the recipient's immune system.

Robert F. Garry of Tulane University in New Orleans, along with colleagues from Tulane University and the University of Southern California in Los Angeles, exposed HIV to ultraviolet radiation, a process that prevents the virus from reproducing itself or directing the production of new proteins. The irradiated virus killed cells in culture at the same rate nonirradiated HIV killed cells, they report in the October VIROLOGY. The finding supports work from other laboratories indicating that the protein itself, even without genetic expression or viral reproduction, is lethal.

Harvard University researchers have shown that high levels of the protein, which coats the virus, prompted a laboratory cell line to fuse together and die. Several other laboratories, including Robert Gallo's at the National Cancer Institute, showed that HIV with a mutant envelope gene can replicate itself but not kill other cells (SN: 8/16/86, p.104). In addition, Gallo's lab and several other institutions reported in the Oct. 23 NATURE that vaccinia virus saddled with the envelope gene caused white blood cells to fuse and die.

Many vaccines are made of whole viruses that have been inactivated or killed, but the evident lethality of the HIV envelope protein indicates that such an approach could be toxic. "It means that if one is to make a vaccine, you have to inactivate the function of the envelope protein that kills the cells," says Garry.

But while the findings close one door, they may well open another, says Garry. Modification of the envelope protein may be possible. The findings also suggest that the search for a cure should focus on compounds that will interact with the virus particle quickly, before the envelope protein encounters the cell surface and the virus slips in. "Anytime you learn something about a pathogen, you're learning about your enemy," says Garry.