Cow Antibodies Offer Clues for AIDS Vaccine
Scientists produce HIV-blocking antibodies rapidly in calves by using a relatively simple immunization strategy.
Cows don’t naturally acquire the human immunodeficiency virus (HIV), but they do possess immune systems with unique features that may help humans battle the disease.
In a new study, scientists explored whether cow immune systems could be made to churn out potent antibodies called “broadly neutralizing antibodies” or “bNAbs." These important antibodies can halt most HIV strains from infecting human cells and protect animal models from infection, but so far researchers have been unable to prompt the human immune system to produce bNAbs through immunization.
In pursuit of a better understanding of bNAbs, a group of scientists supported by the National Institute of Allergy and Infectious Diseases at the Scripps Research Institute, the International Aids Vaccine Initiative, and Texas A&M University injected HIV immunogens into the flanks of four calves and waited to see how long it would take their immune systems to respond.
The immunogen, a BG505 SOSIP trimer, elicited HIV bNAb responses in the cows “consistently and rapidly,” according to the group. All four cows developed bNAbs to HIV in their blood within 35 to 50 days. The scientists’ work was published online in Nature July 20.
“A minority of people living with HIV produce bNAbs, but only after a significant period of infection, at which point the virus in their body has already evolved to resist these defenses,” said Dennis R. Burton, a lead author of the study and director of NIH’s Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery. “The potent responses in this study are remarkable because cattle seem to produce bNAbs in a relatively short amount of time. Unlike human antibodies, cattle antibodies are more likely to bear unique features and gain an edge over complicated HIV immunogens.”
While cow bNAbs aren’t likely to be suitable for clinical use for humans in their current form, the group’s findings offer hope that researchers may one day be able to develop a broadly effective AIDS vaccine for humans.