Can cows help develop an HIV vaccine? A new study shows that cows' quick immune response could hold the key to creating a human HIV vaccine.
Immunogens And Antigens
Scientists supported by the National Institutes of Health (NIH) just made a significant step toward hopefully developing an effective HIV vaccine after an experiment that involved cows. What they found was that unlike humans, cows actually have the capability to develop HIV neutralizing antibodies (bNAbs) much faster than humans can.
What researchers essentially did was to inject four calves with proteins designed to mimic the ones on the surface of HIV in hopes of inducing an immune response. In a matter of 35 to 50 days, all four calves have already developed bNAbs.
Compared to HIV-infected humans in whom only 10 to 20 percent develop bNAbs and only after two years of infection, this feat by the calves is truly groundbreaking.
What's more, one of the cows' immune response was able to neutralize 20 percent of the HIV strain in 42 days, while another was able to neutralize a staggering 96 percent of the HIV strain within 381 days.
Bovine Immune Response
Upon isolating the antibodies developed by the immunized calves, researchers found that they have a particularly potent antibody, which binds to a site that the HIV virus uses to infect cells. Further, they were also found to have longer loops of HCDR3 that develop at a much higher frequency.
Extended HCDR3 regions are able to penetrate the sugar molecules on the surface of HIV, thereby reaching its concealed regions and eventually neutralizing it. In humans, these longer HCDR3 regions are observed in people who have lived with HIV for longer periods.
The incredibly quick and effective immune response of the young bovines is a promising discovery in the quest to hopefully develop a potent HIV vaccine.
How Do Cows Do It?
So how do cows develop the antigens for an exclusively human virus so quickly? Even the researchers are unsure. One guess that they make is that perhaps the cows' gastrointestinal systems are the key.
Given that cows have multi-chambered stomachs that allow them to properly digest their main meal of grass, it's possible that the large population of bacteria in their guts are responsible for building such a powerful immune response.
Hope For A Vaccine
Although this research shows incredible promise, it still does not guarantee the development of an HIV vaccine in the near future. Cows differ greatly from humans, and what's more, HIV is a human virus, so it is not very easy to predict how these results will translate to the human immune response.
Still, it is a very promising development, especially since humans tend to produce bNAbs only after a long time of living with the infection, by which time the virus has already developed its own immunity to the human defenses.