January 15, 2016

Study Provides Additional Insights for AIDS Vaccine Design

A new study helps AIDS vaccine researchers further understand how HIV interacts with its host, and how some people naturally produce antibodies against the virus’ many variants. The study, authored by researchers from the International AIDS Vaccine Initiative (IAVI) and partners, was published 14 January in PLOS Pathogens.

HIV is the most challenging virus humankind has ever faced. It changes very rapidly, varies by region and escapes the human immune system’s responses. A few of the people who contract HIV naturally produce powerful antibodies that can neutralize many of the virus’ variants. IAVI and many fellow researchers are working to design and develop a vaccine that can mimic and accelerate this lengthy process.

The new study suggests that both viral and host factors may be critical for the development of such broadly neutralizing antibodies (bNAbs), and that one “supersite” on HIV’s envelope protein may be a particularly favorable target for vaccine design. This research utilized samples from 439 newly infected volunteers in Protocol C, a large observational study by IAVI and partners in Eastern and South Africa supported by the United States Agency for International Development (USAID). About 15 percent developed bNAb responses, on average three years after infection. Gender, age and geographical origin appeared to have no influence on the development of bNAbs. However, the study showed that broad neutralization was associated with high viral load, low levels of particular immune cells, infection with one particular HIV subtype, and the presence of a particular gene in the host.

“These findings add to the important lessons that AIDS vaccine science continues to learn from large observational studies like Protocol C,” said Mark Feinberg, IAVI President and CEO. “The volunteers who participate in these studies are critical and valued partners in the effort to design a safe and effective AIDS vaccine.”

USAID administers the U.S. foreign assistance program providing economic and humanitarian assistance in more than 120 countries worldwide.

Broadly Neutralizing Antibody Responses in a Large Longitudinal Sub-Saharan HIV Primary Infection Cohort,” by Elise Landais, Pascal Poignard, et al.

IAVI and partners, with support from USAID, launched Protocol C and other studies in 2006 to better understand how HIV infection and immune responses vary by region and progress over time. Protocol C enrolled more than 600 volunteers who were monitored regularly and tracked once they tested positive for HIV. (All volunteers are provided with or referred for HIV care, including anti-retroviral treatment.) To date, more than 190,000 Protocol C samples have been collected, with 27,000 shared with researchers worldwide and more than 70 related papers published. Protocol C samples are also central to VISTA, an international consortium to design and assess AIDS vaccine candidates for Africa, with Africa.