Test to detect drug-resistant HIV strains could help provide earlier treatment

Jan 9 2007

A test to detect drug-resistant HIV strains in people with low levels of drug-resistant viral loads could help physicians provide more effective treatment earlier to HIV-positive people, according to a study published on Sunday in the online edition of the journal Nature Methods, BBC News reports (BBC News, 1/8).

Researchers at the Duke University Medical Center developed a test that can detect antiretroviral-resistant strains of HIV even if they comprise 1% of an individual's viral load.

Current tests can detect drug-resistant strains if they make up at least 20% of a person's viral load, the McClatchy-Tribune/Baltimore Sun reports (McClatchy-Tribune/Baltimore Sun, 1/8).

For the study, the researchers identified HIV genes with mutations known to be linked to drug resistance and added fluorescent tags to genetic material from participants' blood samples.

They assigned green tags to the mutated genes and red tags to nonmutated genes.

A computer program counted how many molecules had each color tag.

The test could identify single mutated viruses and viruses with more than one mutation, BBC News reports (BBC News, 1/8).

The Duke test to date has been conducted only for research purposes, but Duke researchers are seeking patents to enable them to develop a diagnostic test for commercial use, the McClatchy-Tribune/Sun reports.

"A lot of questions are still unanswered, but it's an important step forward," Peter Leone of the University of North Carolina's School of Medicine, who also serves as the medical director of the North Carolina HIV/STD Prevention and Care Branch, said.

He added that if the test proves effective, it would "improve the odds that the first course of treatment is going to be successful" (McClatchy-Tribune/Baltimore Sun, 1/8).

Study co-author Feng Gao said the test also might enable researchers to understand how HIV-positive people develop drug resistance because it is unclear which combinations of virus strains people need to carry to develop substantial drug resistance, BBC News reports (BBC News, 1/8).

According to some studies, 15% or more of patients newly diagnosed with HIV have drug-resistant strains of the virus (McClatchy-Tribune/Baltimore Sun, 1/8).