“One of, if not the major challenge in development of a safe and effective HIV vaccine, is the inability to elicit broadly neutralizing antibodies in humans,” Wayne Koff, president and CEO of the Human Vaccines Project, said in an email. Koff was not affiliated with the new study.
The goal of developing an effective vaccine hinges on prompting a person’s immune system to begin quickly producing what are called broadly neutralizing antibodies (bNAbs) in order to fight off infection.
And that’s where the cows come in.
RELATED: New Test Could Help Identify ‘Hidden’ HIV
The researchers, supported by NIH, thought cows might yield insights on fighting HIV when they looked at the structure of human bNAbs that were produced by people with long-term HIV infections. Specifically, they looked at a looped area on the antibodies called HCDR3.
One of the distinct features of the HIV virus is that it is surrounded by a thick envelope of sugars, called the glycan shield, that is hard for normal-sized antibodies to penetrate. The scientists realized that in the small percent of humans that do produce HIV bNAbs those antibodies have extra-long HCDR3 loops that can pierce through the glycan shield.
Antibodies in cows also have naturally long HCDR3 loops, though no one is quite sure why. One theory is, because cows have multiple stomachs with lots of bacteria, they need extra-powerful antibodies to protect them from infection.
The researchers injected the four cows with an HIV immunogen, a molecule that can prompt the HIV immune response. To their surprise, not only did the cows produce HIV bNAbs, but they produced them quickly — within 35 to 50 days. At just over a year, one cow produced bNAbs against 117 strains of HIV.
“These new data are very interesting and encouraging,” said Dan Barouch, director of the Center for Virology and Vaccine Research at Harvard Medical School. “Although cows are not humans, these data provide important insights on how the immune system responds to HIV [immunogens],” Barouchs did not take part in the research.
The scientists who undertook the study say they hope that their findings will pave the way for greater understanding of how the human immune system responds to HIV.
"HIV is a human virus," Devin Sok of the Department of Immunology and Microbiology at The Scripps Research Institute said in a press release, "but researchers can certainly learn from immune responses across the animal kingdom."
WATCH: One Woman's Triumph Over HIV in Ghana