December 18, 2012
Researchers at Rockefeller University, New York, appear to have found another approach to treating HIV infection. They have shown that it is possible to harness proteins from the human immune system to suppress the virus in mice without the need for daily application as is done with current antiretroviral drugs. Using a combination of five different antibodies, Florian Klein and colleagues at Michel Nussenzweig's Laboratory of Molecular Immunology were able to effectively suppress HIV-1 replication and prevent the virus for 60 days after termination of therapy. They used "humanized mice" as normal mice do not have the receptors to be infected with HIV-1.
HIV-1 evades the human immune system's attacks by mutating; but with the combination of the new antibodies, mutation did not work. The antibodies target HIV-1's surface protein, gp160, a molecule that forms a spike that attaches to host cells. Five antibodies in unison were required to stop gp160. The five antibodies were too complicated for gp160 to mutate in time to avoid them. The antibodies, called broadly neutralizing antibodies, were recently discovered. They were identified and cloned from HIV-infected patients whose immune systems had an unusually high ability to neutralize HIV. These antibodies have been able to prevent HIV from infecting non-human primates, which leads to a possibility of a vaccine for humans. However, it was felt that they would have little or no effect on established infections.
Klein stated that the results are encouraging enough to prompt an investigation of these antibodies in clinical trials. He surmised that a combination of antibodies and antiretroviral therapy may lead to a treatment for humans that will not require daily medication.
The study, "HIV Therapy by a Combination of Broadly Neutralizing Antibodies in Humanized Mice," was published in the journal Nature (2012; 492 (7427):118 DOI: 10.1038/nature11604).
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