HIV Vaccine Elicits Potent Response in Nonhuman Primates

A study conducted by researchers at Weill Cornell Medicine has demonstrated that a series of six vaccinations containing a modified protein from the surface of HIV particles stimulated initial steps of a potent immune response in young nonhuman primates. According to the researchers, this difficult-to-achieve response represents an important step toward providing full and potentially lifelong protection against the virus, suggesting childhood immunization against HIV could one day provide protection before risk of contracting this potentially fatal infection dramatically increases in adolescence.

In the study, the researchers started with an experimental vaccine developed previously from spike proteins on the envelope of HIV particles. The modified vaccine was administered to five young primates in three priming doses, starting less than a week after birth. This was followed up with three doses of the vaccine matching the original HIV envelope protein, with the last dose given when the animals reached 78 weeks old, roughly equivalent to 4 or 5 years old for a human. As a control, five animals received all six doses of the original envelope protein vaccine.

Three of the five animals who received the modified version of the priming vaccine developed antibodies that appeared to be precursors to the sought after broadly neutralizing response. Tests suggested these antibodies attacked the site the virus uses to invade CD4 T cells. However, they were not yet fully effective against the same breadth of HIV strains as mature broadly neutralizing antibodies. One of the three animals also showed signs of developing the mature, broadly neutralizing response.

According to Ashley Nelson, PhD, an assistant professor of immunology research in pediatrics at Weill Cornell Medicine, the next step is figuring out how to reliably elicit a full-on broadly neutralizing response: “We still need to identify the right combination of viral proteins to get us further down that path, starting from the earliest stages in life when multi-dose vaccines are commonly given.”