Injection of Specific Antibodies May Reduce HIV Viral Load

Dr. Dan BarouchWhile the role of antibodies in preventing infection is clear, a growing number of researchers are enlisting antibodies to help cure HIV. One of the most promising avenues to achieve this is passive immunization, in which antibodies are injected directly into the patient.

In the August issue of the Journal of Virology, amfAR-funded scientist Dr. Dan Barouch of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston, with colleagues from the Ragon Institute of MGH, MIT, and Harvard in Cambridge, MA, the National Institutes of Health in Bethesda, MD, and Leidos Biomedical Research and Frederick National Laboratory Center for Cancer Research in Frederick, MD, uses a passive immunization approach to explore the potential role of antibodies in curing HIV infection.

Barouch and associates tested two antibodies, PGT121 and N6, in 18 monkeys infected with SHIV, a combination of HIV and SIV (the simian form of the virus). Both PGT121 and N6 are known to be active against HIV. The monkeys were treated with either PGT121 or N6, a combination of both, or a placebo. The antibodies reduced the viral load in the monkeys.

The researchers then measured SHIV DNA in the blood and lymph nodes to see if the antibodies had any effect on infected cells. They found significantly reduced levels of SHIV DNA in the blood two weeks after the antibodies were administered; in the lymph nodes, SHIV DNA dropped markedly after 10 weeks. The authors note that the monkeys’ naturally occurring antibodies and immune responses to SHIV were not enhanced as a result of the PGT121 or N6 infusions, arguing against their contribution to the observed viral effects.

These results suggest that passive immunization using these antibodies might, under the right conditions, kill cells of the persistent viral reservoir and thus play a role in curing HIV.