How cows are boosting the search for an HIV vaccine

Cows in Pasture
Cow antibodies are inspiring a new approach to developing a vaccine against HIV.

Despite enormous advances in drug therapies to treat HIV, the quest to develop a vaccine against the virus that causes AIDS has been unsuccessful. Now an international group of scientists is turning to a surprising ally in this ongoing effort: the cow.

Scientists at the Antibody Discovery and Development at the International AIDS Vaccine Initiative (IAVI) are finding inspiration for a new type of HIV vaccine in antibodies that cows’ bodies produce naturally. These antibodies have long loops—a feature that may allow them to attack hard-to-reach areas on the surface of viruses, thereby preventing infection.

That’s important, because scientists figured out years ago that some people who are able to live with chronic HIV infection produce a broadly neutralizing antibody (bnAb) that uses long loops to keep the virus at bay. The similarities between those long loops in cows and people led them to a simple question: "Since we know that some human bnAbs have longer-than-average loops, would immunizing animals with similar antibody structure result in the elicitation of bnAbs against HIV?" said Devin Sok, Director, Antibody Discovery and Development and IAVI, in a press release.

Working with veterinarians from the Scripps Research Institute and Texas A&M University, the researchers tested an “immunogen,” an antigen that elicits an immune response, called BG505 SOSIP in four cows. BG505 SOSIP mimics a protein on the surface of HIV that is a target for bnAbs. They weren’t sure it would work—it had failed to elicit a meaningful immune response in other animal models—but it did.

All of the cows developed bnAbs to HIV within 52 days, according to the release. People who are HIV-positive, by comparison, take many years to build up those antibodies, and most never do. The research was published in the journal Nature.

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Cows are becoming an increasingly popular research ally, and not just in HIV. Last year, scientists at the University of Parma in Italy described progress developing a treatment for multiple myeloma that combines a cow virus with human stem cells from bone marrow. The virus appears to indirectly cause the death of multiple myeloma cells, they reported.

Even though cows don’t get HIV, the IAVI research should inspire new approaches to vaccine development, because it demonstrates the importance of increasing the population of human antibodies that have long loops, the team suggests. The finding may have even broader implications beyond HIV. "This surprising set of results warrants further exploration and has potential applications not only to HIV prevention and treatment, but to the rapid development of antibodies and vaccines against other infectious diseases," said IAVI CEO Mark Feinberg.