Early Vaccine Study Shows HIV Neutralizing Antibodies Appear Within Weeks

Elusive HIV antibodies were triggered within weeks during a small-scale HIV vaccine study done at the Duke Human Vaccine Institute, according to a press release posted last month. This finding is significant because it can take years for the body to establish these antibodies. The research was published mid-May in the journal Cell.

HIV remains one of the world’s deadliest diseases. In 2022, about 630,000 died worldwide. About 39 million are living with it today, KFF reports.

HIV can be treated with antiretroviral therapies, but a vaccine isn’t available for several reasons, according to the International AIDS Vaccine Initiative, a nonprofit research organization that develops vaccines. HIV is not recognized by the immune system because it is covered in a layer of sugar molecules that hide the areas where antibodies can attach. HIV also has extreme genetic variability, meaning vaccine antibodies would need to tackle many genetic forms. No one with HIV has ever cleared it on their own, so there is no blueprint for what vaccine-induced immunity would look like.

Duke’s vaccine is designed to target the outer envelope of HIV called the membrane proximal external region (MPER). This membrane remains stable even as the vaccine mutates, leading to widespread infection. The vaccine candidate stops this from happening by destroying this envelope using antibodies.

The phase 1 trial enrolled 20 healthy, HIV-negative people. Fifteen received two of the four doses of the vaccine and five received three doses. After just two doses, the vaccine had a 95% serum response rate and a 100% blood CD4+ T-cell response rate.

The Duke trial stopped when one participant reported an allergic reaction, which was non-life threatening, likely from a vaccine additive. Researchers said it was comparable to one of the rare instances of a COVID-19 vaccine allergic reaction.

“This work is a major step forward as it shows the feasibility of inducing antibodies with immunizations that neutralize the most difficult strains of HIV,” senior author Barton F. Haynes, M.D., director of the Duke Human Vaccine Institute (DHVI), said in a press release. “Our next steps are to induce more potent neutralizing antibodies against other sites on HIV to prevent virus escape. We are not there yet, but the way forward is now much clearer.”

A successful HIV vaccine must have at least three components to target three sites on the envelope.

“Ultimately, we will need to hit all the sites on the envelope that are vulnerable so that the virus cannot escape,” Haynes added. “Now that we know that induction is possible, we can replicate what we have done here with immunogens that target the other vulnerable sites on the virus envelope.”