Experimental vaccine partially protects monkeys from HIV-like infection

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.

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

Journal reference: Nature search and more info website

Provided by National Institutes of Health

not rated yet

Related Stories

Some monkeys born with gene that protects against AIDS

May 04, 2011

A certain gene in some monkeys can help boost vaccine protection against simian immunodeficiency virus (SIV), a trait that could help researchers develop better AIDS vaccines for humans, suggested a study ...

Study offers insights into failed HIV-1 vaccine trial

Jul 20, 2009

Following the disbandment of the STEP trial to test the efficacy of the Merck HIV-1 vaccine candidate in 2007, the leading explanation for why the vaccine was ineffective - and may have even increased susceptibility to acquiring ...

Recommended for you

New study reveals why some people may be immune to HIV-1

7 hours ago

Doctors have long been mystified as to why HIV-1 rapidly sickens some individuals, while in others the virus has difficulties gaining a foothold. Now, a study of genetic variation in HIV-1 and in the cells ...

Virus discovery could impact HIV drug research

14 hours ago

A research team led by Portland State University (PSU) biology professor Ken Stedman has unlocked the structure of an unusual virus that lives in volcanic hot springs. The discovery could pave the way for better drugs to ...

UN warns over threat of AIDS rebound

Nov 19, 2014

South African actress Charlize Theron threw her weight Tuesday behind an urgent new UN campaign to end AIDS as a global health threat by 2030.

User 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.