It’s unknown whether topically applied ARVs used in prevention would enter the human bloodstream at levels so that if a person does contract HIV, that same ARV would be useless in fighting the disease. There is concern that using ARVs for prevention could drive up human resistance to these medications, in a similar way that using antibiotics to fight common colds can lead to their ineffectiveness in fighting bacterial infections later. “This issue needs to be studied carefully in both nonhuman primates and humans before large-scale clinical trials are commenced,” wrote 15 prominent U.S. and Canadian AIDS researchers in a paper published in the July 25 issue of Science.
In the harshly worded article, the researchers called for "some serious soul searching within the microbicide field," including better management and collaboration and more attention paid to underlying science, such as more rigorous testing on animals and trying out a variety of molecules that attack HIV at different points in the replication cycle of the virus in stead of focusing on just one strategy.
"We’re still very hopeful that an effective microbicide will come out of this," says Robert Grant, lead author of the article and an immunologist at the Gladstone Institute of Virology and Immunology at the University of California, San Francisco. "At this stage, I think we should keep as many options open as possible. We do not have a proven concept."
He warns that it would be a mistake for researchers to invest all of their time and resources into ARVs, given that "It's not precisely known whether ARVs will work for prevention."
To date, no microbicide has worked successfully to prevent the spread of HIV. But, like efforts to develop an HIV vaccine, hope keeps researchers trying and donors giving, says Anna Forbes, deputy director of the Global Campaign for Microbicides, a Washington, D.C.–based coalition of 300 nongovernmental organizations working on the issue. "It would change the landscape considerably for women," Forbes says. "Think about the difference the Pill made in a decade. Microbicides have that same potential."