[NEW DELHI] Scientists in United States have developed a faster and cheaper method of screening for drug-resistant HIV.
Screening patients for drug-resistant strains of HIV helps doctors choose the most effective drug combination, and helps prevent treatment failure.
Treatment of patients infected with even small numbers of these resistant strains can often fail, because the small resistant populations survive drug treatment and continue the infection.
The increased availability of antiretroviral drugs to treat HIV/AIDS in developing countries is expected to contribute to a global rise in drug-resistant HIV strains.
Most developing countries across Africa and Asia cannot afford current methods to detect resistant strains. In addition, current methods are time-consuming, and not sensitive enough to detect small numbers of drug-resistant HIV.
The new technique, developed by scientists at the University of Pennsylvania School of Medicine in the United States, combines two genetic methods. They first analysed DNA from seven HIV mutant strains, including three showing resistance to many drugs. The scientists then indexed the DNA sequences using a genetic marker as a tag.
Using the index, they then characterised mutations in the drug resistant strains using a DNA sequencing technique called 'pyrosequencing' that can analyse millions of DNA sequences in a single-day test. Thus, they were able to identify mutations that contribute to drug resistance.
The researchers say the new method is faster and cheaper than current methods because it can analyse multiple sequences in a short time.
The findings of were published last week (28 June) in Nucleic Acids Research.
In a related development, Joanne Stekler and Robert Coombs from the Center for AIDS and STD in Seattle, United States, note that anti-retroviral resistance is an emerging issue in resource-poor countries with limited experience in dealing with resistant strains of HIV.
In an article in the June issue of the Journal of Infectious Diseases, the authors suggest that treatment programmes should be coupled with HIV drug-resistance surveillance programmes.
Nucleic Acids Research doi:10.1093/nar/gkm435 (2007)
Journal of Infectious Diseases 96, 336 (2007)