BY HIV Plus Editors
May 01 2010 12:00 AM ET
New research suggests that many of the drug-resistant strains of HIV that have evolved over the past decade in San Francisco are more transmissible than had been thought. And experts predict that within the next five years these strains are likely to cause a new wave of virus that's highly resistant to medications, potentially proving disastrous by hindering control of the pandemic.
In a study published January 14 on the website of the journal Science, researchers from the Semel Institute for Neuroscience and Human Behavior at the University of California, Los Angeles, and the University of California, San Francisco's HIV AIDS Program at San Francisco General Hospital developed a mathematical model that tracks the transmission of multiple strains of HIV. The model can be used to predict drug resistance in any setting where individuals are treated for HIV infection. While in this case it was applied to San Francisco, the researchers found that the drug-resistant strains emerging in that city are also very likely to emerge in many African countries where treatment is just beginning.
"This isn't just about San Francisco," says senior author Sally Blower, director of UCLA's Center for Biomedical Modeling and a member of the UCLA AIDS Institute. "It's basically about many other communities in resource-rich countries and has significant implications for global health. San Francisco is like the canary in the mine. In fact, the most significant implications of our work are for countries where treatment is just being rolled out."
"What is very unsettling," Blower continues, "is that our modeling shows that the current strategy for HIV elimination that is being proposed by the World Health Organization could inadvertently make things worse and significantly increase levels of drug resistance in many African countries."
The researchers studied the evolution of drug-resistant strains over the past 20 years and predicted their spread over the next five years, according to Robert Smith, who was a postdoctoral fellow in Blower's lab when the research was conducted. Surprisingly, he says, their analysis showed that HIV was becoming more than simply stronger in its resistance to medications. "What was very disturbing was we found that some of the drug-resistant strains were increasing," says Smith, now an assistant professor in the department of mathematics and statistics at the University of Ottawa.
The model was able to explain this increase, according to Justin T. Okano, also a research associate in Blower's group. "What is going on in San Francisco is very complicated, but in a nutshell," he elaborates, "it is due to the bug, the drugs, and sex."