In a collaborative study with the World Health Organization and seven other laboratories, researchers at the Stanford University School of Medicine have compiled a list of 93 common mutations of the AIDS virus associated with drug resistance that will be used to track future resistance trends throughout the world.
The researchers analyzed data from about 15,220 patients across the globe to develop an updated and accurate list of the most common, resistance-related mutations of the virus. The list will be published March 6 in the online journal PLoS-One.
"The epidemic is changing, especially as new drugs are being developed," said Robert Shafer, MD, associate professor of infectious diseases and geographic medicine at Stanford and the senior author of the paper. "To effectively track the spread of drug resistance, particularly transmitted drug resistance, you need a sensitive and specific list that's considered standard and is adopted by all the surveillance studies."
The list is important, he said, as it helps countries gauge the effectiveness of their HIV medication programs. But assembling such a list can be a challenge, particularly with a virus that has so many resistance-related variants. On the one hand, if the list is too liberally defined, then HIV drug funders and providers may believe resistance is more widespread than is actually the case.
"That will cause problems in countries. They may be concerned about whether their drugs will work," Shafer said.
On the other hand, if the list is too restrictive, there is a risk of underestimating the actual extent of resistance, he said.
"So there is a real challenge to using the right number of mutations," Shafer said.
In 2007, Shafer and his colleagues published a similar list of 80 HIV mutations that has since served as the basis for global AIDS surveillance work. However, with the scale-up of antiretroviral drug programs in the last two years and the introduction of new medications, resistance patterns have changed. So there was a need for a newly updated reference, he said.