Scientists Examine Cow Immune System as Another Avenue for HIV Vaccine

Immunization of cows induces rapid elicitation of broadly neutralizing antibodies to HIV.

Examining the immune system in cows is providing scientists with new insights into preventing HIV infection.

Scientists have long searched for ways to help HIV-positive patients produce more broadly neutralizing antibodies (bNAbs) because they can neutralize a broad array of different HIV viral strains. Unfortunately, inducing bNAbs in humans through an HIV vaccine has thus far been unsuccessful.

“We are faced with a dilemma,” Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told TIME. “People infected do not seem to make really good antibodies in terms of potency and breadth.”

In a study published in Nature, investigators used cows to gain a better understanding of how to harness bNAbs. Although cows do not contract HIV, their immune systems produce unique antibodies against infections.

The investigators immunized 4 cows with HIV immunogens, which elicit an immune response to the virus. The results of the study showed that the BG505 SOSIP immunization induced a rapid elicitation of broad and potent serum antibody responses in all the cows.

A longitudinal serum analysis of 1 cow showed the development of 20% neutralization breadth in 42 days and 96% breadth at 381 days. Furthermore, a monoclonal antibody isolated from the cow harbored an ultra-long HCDR3 of 60 amino acids and neutralized 72% of cross-clade isolates.

In particular, the antibody NC-Cow1 was found to be especially powerful against HIV.

“The kind of insight we get from studying this is an understanding of the mechanisms whereby the cows’ immune system is capable of creating these antibodies,” Fauci told TIME.

Gaining a further understanding of how the immune system produces antibodies against HIV is crucial in the development of an HIV vaccine, even if its bNAbs from cows, according to the study.

The authors noted that the findings help provide insight into developing new treatments for viruses that attack the immune system in humans.

“Immunization of cows may provide an avenue to rapidly generate antibody prophylactics and therapeutics to address disease agents that have evolved to avoid human antibody responses,” the authors concluded.

Study author Devin Sok told TIME, “As a scientist, this is really exciting. To put it into perspective, the first broadly neutralizing antibodies were discovered in the 1990s. Since then, we’ve been trying to elicit these antibodies through immunization, and we’ve never been able to do it until now. Until we have immunized a cow. This has given some information for how to do it so that hopefully we can apply that to humans.”