The cracks are widening in the first line of defense against the virus that causes AIDS - drugs that inhibit the essential viral enzymes called proteases and reverse transcriptase. At the World Conference against AIDS 12 in Geneva, Switzerland, separate teams of US and Swiss researchers reported today the first cases in which HIV strains resistant to both classes of drugs were sent to new confirmed victims. While multidrug resistance does not come as a surprise, researchers had hoped that HIV, by mutating to survive exposure to the two classes of compounds will be rendered incapable of infecting new hosts.
The ability of HIV to mutate rapidly -and, of course, hiding in the immune system of its host - was one of the worst AIDS epidemics of infectious diseases worldwide. But the tide began to turn in late 1995 and early 1996, when the US Food and Drug Administration approved the first inhibitors 3 protease that prevent HIV machines clipping viral proteins newly formed just the right size needed to assemble new virus. Used in combination with reverse transcriptase inhibitors, which prevent the HIV genome to be incorporated in infected cells, the drugs have caused new cases of AIDS in the United States to decrease by 15% compared to early 1996 in mid-1997 - the first decline since the beginning of the epidemic in 1981.
The drugs seemed as promising as agents for blocking HIV transmission. Although AIDS patients regularly develop strains of HIV resistant to one or more protease inhibitors, only a handful of unconfirmed reports have suggested that resistant strains - probably less virulent because of mutations that help them survive treatment drug - could be passed on to new victims. "The thought was that the inhibitor resistant virus protease was unlikely to be transmitted to new hosts," says Frederick Hecht epidemiologist at the University of California, San Francisco. At the conference, however, Hecht described a patient who was infected with HIV already resistant strain in six of the 11 approved antiretroviral medicines, including four protease inhibitors. A second study presented by researchers from Geneva University Hospital had three cases of similar-resistant HIV transmission drugs.
These reports represent "the best documentation to date of the multiple drug resistance against HIV," said infectious disease specialist Joel Gallant, director of the Moore HIV Clinic at the Medical School of the Johns Hopkins University. "We do not yet know the implications of resistance to multiple drugs public health, but it will likely be increasingly important," says Gallant, adding that it is a threat that highlights the need to . prevent HIV transmission Hecht agrees: ". While we must continue to develop new drugs against HIV, they are all likely to be prey to resistance "
0 Komentar