Antibody Infusions Prevent Acquisition of Some HIV Strains

On January 26, 2021, the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH), announced findings that an investigational anti-HIV antibody delivered intravenously once every eight weeks safely and effectively prevented acquisition of HIV strains sensitive to that antibody. The Phase 2b trials of the Antibody-Mediated Prevention (AMP) Studies are being conducted jointly by the HIV Vaccine Trials Network (HVTN) and HIV Prevention Trials Network (HPTN).

Although currently available treatments for HIV have significantly reduced transmission of the virus, diverse communities worldwide, especially in areas where HIV subtypes are predominant, need acceptable long-acting HIV prevention strategies. Broadly neutralizing antibodies (bNAbs), which arise naturally in some people living with HIV and can stop a wide range of HIV strains from infecting human cells in the laboratory, are considered promising candidates for long-acting HIV prevention.

The AMP Studies aimed to determine whether infusions of a bNAb called VRC01 are safe, tolerable and effective at preventing HIV acquisition. The NIAID Vaccine Research Center (VRC) discovered VRC01 in 2010 in the blood of a person living with HIV and subsequently manufactured the antibody for the AMP Studies. The two trials included more than 4,600 participants. Men and transgender people who have sex with men were enrolled in the Americas and Europe, geographic regions where HIV subtype B predominates. Women were enrolled in sub-Saharan Africa, where HIV subtype C is dominant. “Insights gleaned from the AMP Studies lay the foundation for future development of long-acting antibody-based HIV prevention tools and, ultimately, a vaccine,” NIAID Director Anthony S. Fauci said in a press release.

The study found that VRC01 infusions did not provide significant protection against HIV acquisition compared to a placebo. Investigators attribute this to the finding that only 30% of HIV strains circulating in the regions where the trials were conducted were sensitive to VRC01. “These observations suggest that more than one antibody likely will be needed to offer effective protection against the wide variety of HIV strains, similar to how combinations of antiretroviral drugs are required to treat HIV,” said Larry Corey, M.D., AMP Studies protocol chair and principal investigator of the HVTN. “The AMP Studies have identified a laboratory test to predict the efficacy of an antibody against different HIV strains and have given us the tools we need to estimate the amount of antibody needed for protection.”

More information of the AMP Studies is available at

—Reporting by Hank Trout

Hank Trout, Senior Editor, edited Drummer, Malebox, and Folsom magazines in the early 1980s. A long-term survivor of HIV/AIDS (diagnosed in 1989), he is a forty-year resident of San Francisco, where he lives with his husband Rick.