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Researchers Design Global HIV Vaccine that Shows Promise in Early Studies

October 24, 2013
In a new study published October 24 in the journal Cell, a scientific team has shown that bioinformatically optimized HIV vaccine antigens known as “mosaic” antigens might be useful in the design of a global HIV vaccine.

The worldwide diversity of HIV poses a critical challenge for designing a globally-effective HIV vaccine. In a new study published October 24 in the journal Cell, a scientific team has shown that bioinformatically optimized HIV vaccine antigens known as “mosaic” antigens might be useful in the design of a global HIV vaccine.

“In this study, we show for the first time that bioinformatically optimized HIV vaccine antigens can afford partial protection in rhesus monkeys against challenges with a stringent simian-human immunodeficiency virus,” said lead author Dan H. Barouch, MD, PhD, the Director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center (BIDMC) and Professor of Medicine at Harvard Medical School. The study, conducted at Harvard University, represents the first evaluation of the protective efficacy of a candidate global HIV antigen strategy in nonhuman primates. These mosaic vaccine antigens aim to expand the breadth of immune responses and provide protection across a genetically diverse HIV epidemic.

Barouch and his team studied the immunogenicity of HIV mosaic Env/Gag/Pol antigens administered to monkeys using viral vectors. (Env, Gag, and Pol are three major HIV proteins.) After immunization, the monkeys were repetitively exposed to a difficult-to-neutralize strain of the simian-human immunodeficiency virus and the investigators evaluated the ability of the vaccines to block infection. 

Researchers observed an 87 to 90 percent reduction in the immunized monkeys’ probability of becoming infected each time they were exposed to the virus. The investigators found that the immunized monkeys mounted antibody responses against diverse strains of HIV and the monkeys also mounted cellular immune responses to multiple regions of the virus. 

“A vaccine that can provide gloabal protection from HIV, along with other proven prevention techniques, is our best hope to control the HIV pandemic. These data are encouraging in that they give us optimism that a globally-effective vaccine might be possible,” said Col. Nelson Michael, U.S. Military HIV Research Program (MHRP) Director and senior author of this study. According to Barouch, scientists are planning to advance this HIV vaccine candidate into clinical trials next year.

The vaccine regimen tested in the study has two components. The MVA vaccine was developed by MHRP scientists in collaboration with the National Institutes of Allergy and Infectious Diseases (NIAID) Laboratory of Viral Diseases. The two Ad vaccines are based on the AdVac® platform developed by Crucell Holland BV, one of the Janssen Pharmaceutical Companies. 

In addition to BIDMC and MHRP, other coauthors include the Los Alamos National Laboratory, the Laboratory of Viral Diseases at NIAID and Crucell. Funding for the study was provided by NIAID; the Ragon Institute of MGH, MIT, and Harvard; MHRP; and the Bill and Melinda Gates Foundation.