Findings from a study published in Nature in July 2017 reveal that scientists are using cows to better understand the Human Immunodeficiency Virus (HIV) and develop an HIV vaccine.1 After decades of research, including clinical trials of different HIV vaccine candidates,2 there is still no effective vaccine because the virus mutates at a rapid rate and the human body does not produce a strong immune response to it.3
HIV vaccine researchers have yet to figure out why people diagnosed with HIV do not develop antibodies against the virus. It is estimated that only 10 to 20 percent of people produce broadly neutralizing antibodies that defend cells against the virus. Moreover, even among those people who do produce antibodies, the bNAbs only begin to develop after about two years of infection.
According to Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), which has long financially supported HIV vaccine research, “We are faced with a dilemma. People infected do not seem to make really good antibodies in terms of potency and breadth.”3
This new study shows that unlike humans, cows are able to develop bNAbs at a faster rate than human beings, even though scientists maintain that cows cannot be infected with HIV.4 Researchers believe that this finding might be the key to manipulating the human immune system to overcome its struggle of developing bNAbs to HIV.
The study’s author, Devin Sok, PhD, states:
One approach to a preventive HIV vaccine involves trying to elicit broadly neutralizing antibodies in healthy people, but so far the experiments have been unsuccessful, in both human and animal studies. This experiment demonstrates that not only is it possible to produce these antibodies in animals, but we can do so reliably, quickly, and using a relatively simple immunization strategy when given in the right setting.5
In the study, four cows were injected with HIV immunogens, which are essentially proteins used to trigger an immune response to the virus.3 Analysis from one of the cow’s showed that its immune response was able to neutralize 20 percent of the virus in 42 days and 96 percent in 381 days, which is considered to be a quicker and much more effective antibody response when compared to humans.5
Researchers are unsure why cows are able to develop antibodies to a virus that is thought to exclusively attack humans; however, they suspect the answer may lie in a cow’s gastrointestinal tract. The multi-chambered guts of cows allow for proper digestion and fermentation of grass.4 It is believed that a large population of bacteria in their guts is responsible for strengthening their immune responses.4
“From the early days of the epidemic, we have recognized that HIV is very good at evading immunity, so exceptional immune systems that naturally produce broadly neutralizing antibodies to HIV are of great interest—whether they belong to humans or cattle,” states Dr. Fauci.6
Public health officials working globally with vaccine developers view an HIV/AIDS vaccine as one that would be used universally by everyone in the world to, as Dr. Fauci said in 2013, create the first “AIDS free generation.”7 Currently, researchers testing candidate HIV/AIDS vaccines in South Africa, where one in five people are thought to be infected with the virus, are hoping to prove at least a 50 percent efficacy.8
Larry Corey, MD, principal investigator for the U.S.-based HIV Vaccine Trials Network, the world’s largest publicly funded multi-disciplinary international collaboration facilitating the development of HIV/AIDS vaccines, pointed out in a 2016 MedPage Today article that achieving a 50 percent efficacy rate for an HIV/AIDS vaccine “is better than some versions of the influenza virus [vaccines].”9
Commenting on the importance of the HIV/AIDS vaccine trials going on in South Africa, Glenda Gray, President and CEO of the South African Medical Research Council, said, “A vaccine is the ultimate female prevention tool,” she said. “You put it in your arm and it works in your vagina.”9
1 Sok D., Le KM, Vadnais M et al. Rapid elicitation of broadly neutralizing antibodies to HIV by immunization in cows. Nature 2017; 548: 108-111.
2 Sheets RL, Zhou T, Knezevic I. Review of efficacy trials of HIV-1/AIDS vaccines and regulatory lessons learned: A Review from a regulatory perspective. Biologicals 2016; 44:73-89.
3 Sifferlin A. How Cows Are Helping the Fight Against HIV. TIME July 20, 2017.
4 Chan A. Cows Could Be Key to Effective HIV/AIDS Vaccine. Tech Times July 22, 2017.
5 Cow antibodies yield important clues for developing a broadly effective AIDS vaccine. Science Daily July 20, 2017.
6 Gallagher J. “Mind-blowing” Cows Hold Clue to Beating HIV. BBC News July 21, 2017.
7 Fauci AS. An AIDS-free generation is closer than we think. The Washington Post July 11, 2013.
8 Brown RL, Bernstein L. Major HIV vaccine trial in South Africa stokes hope. The Washington Post Nov. 25, 2016.
9 Smith M. HIV Vaccine Draws Renewed Interest. MedPage Today July 21, 2016.