Experimental vaccine partially protects monkeys from HIV-like infection

January 4, 2012, National Institutes of Health

Results from a recent study show that novel vaccine combinations can provide partial protection against infection by Simian Immunodeficiency Virus (SIV) in rhesus monkeys. In addition, in the animals that became infected, the optimal vaccine combinations also substantially reduced the amount of virus in the blood. Results from the studies were published online today in the journal Nature.

This proof-of-concept study, which tested MVA, Ad26, and Ad35 vector-based vaccines, is the first to show partial vaccine protection in the stringent animal model involving heterologous, neutralization-resistant SIVmac251 viral challenges in . Preclinical studies of have typically shown post-infection virologic control, however protection against acquisition of infection has previously only been reported using less rigorous viral challenges. The new Ad26/MVA and Ad35/Ad26 vector-based vaccine regimens resulted in over 80% reduction in the per-exposure probability of acquisition of infection against repetitive challenges of SIV, a virus similar to HIV that infects monkeys.

"This study allowed us to evaluate the protective efficacy of several prime-boost vaccine combinations, and these data will help guide the advancement of the most promising candidates into clinical trials," noted lead author Dr. Dan Barouch of Beth Israel Deaconess Medical Center at Harvard Medical School and the Ragon Institute of MGH, MIT, and Harvard.

Further analysis also provided insights into the immune responses that might have provided protection, called "immune correlates." The results show that antibodies to Env (the that makes up the outer coat of the virus) correlated with protection against acquisition, whereas both T cell and correlated with post-infection virologic control.

"These distinct immunologic correlates likely reflect fundamentally different requirements to block establishment of infection compared with controlling after infection," said Col. Nelson Michael, director of the U.S. Military HIV Research Program at the Walter Reed Army Institute of Research and senior author on the paper.

Barouch noted that "we have clearly shown that including Env in the vaccine is beneficial." The findings also suggest that a substantial degree of protection can be achieved against stringent virus challenges, even in the absence of high levels of tier 2 neutralizing antibodies.

These new preclinical studies provide support for advancing the Ad26/MVA prime-boost vaccine candidate into clinical development. Collaborators are planning clinical testing of this HIV regimen in healthy adults at research sites in the U.S., East Africa, South Africa, and Thailand.

Explore further: Antibodies help protect monkeys from HIV-like virus, scientists show

More information: D Barouch et al., Vaccine protection against acquisition of neutralization-resistant SIV challenges in rhesus monkeys. Nature DOI:10.1038/nature10766 (2012).

Related Stories

Antibodies help protect monkeys from HIV-like virus, scientists show

May 5, 2011
Using a monkey model of AIDS, scientists have identified a vaccine-generated immune-system response that correlates with protection against infection by the monkey version of HIV, called simian immunodeficiency virus (SIV). ...

Recommended for you

War in Ukraine has escalated HIV spread in the country: study

January 15, 2018
Conflict in Ukraine has increased the risk of HIV outbreaks throughout the country as displaced HIV-infected people move from war-affected regions to areas with higher risk of transmission, according to analysis by scientists.

Researchers offer new model for uncovering true HIV mortality rates in Zambia

January 12, 2018
A new study that seeks to better ascertain HIV mortality rates in Zambia could provide a model for improved national and regional surveillance approaches, and ultimately, more effective HIV treatment strategies.

New drug capsule may allow weekly HIV treatment

January 9, 2018
Researchers at MIT and Brigham and Women's Hospital have developed a capsule that can deliver a week's worth of HIV drugs in a single dose. This advance could make it much easier for patients to adhere to the strict schedule ...

New long-acting, less-toxic HIV drug suppresses virus in humanized mice

January 8, 2018
A team of Yale researchers tested a new chemical compound that suppresses HIV, protects immune cells, and remains effective for weeks with a single dose. In animal experiments, the compound proved to be a promising new candidate ...

Usage remains low for pill that can prevent HIV infection

January 8, 2018
From gritty neighborhoods in New York and Los Angeles to clinics in Kenya and Brazil, health workers are trying to popularize a pill that has proven highly effective in preventing HIV but which—in their view—remains woefully ...

Researchers find clues to AIDS resistance in sooty mangabey genome

January 3, 2018
Peaceful co-existence, rather than war: that's how sooty mangabeys, a monkey species found in West Africa, handle infection by SIV, a relative of HIV, and avoid developing AIDS-like disease.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.