Research has suggested that llamas may pack a powerful punch against HIV. This is because they not only have conventional heavy and light chain antibodies like those found in humans, they also have heavy chain-only antibodies as shown below.
These so-called “llama antibodies” are smaller than the conventional antibodies found in humans. This helps the antibodies bind more effectively to receptors in cells where the HIV virus lives. Researchers immunized llamas and then identified and isolated five different heavy chain only antibodies against HIV (variations in the VHH region; see above). They exposed isolated human cells that are susceptible to HIV infection to the antibodies and found that the antibodies that target the CD4-binding site of HIV were the most effective at preventing infection. A common problem in developing vaccines against HIV is that different antibodies will sometimes compete with and cancel out the effects of each other. This did not happen with the llama antibodies. In a quote from Healthline, lead study author Laura McCoy said, “The strongest neutralizing antibody always won.” In fact, the study showed that application of llama antibodies were effective at neutralizing 60 different strains of HIV.
A potential problem with using antibodies produced in llamas is that humans may react against the antibodies. However, researchers suspect it may be possible to genetically edit the llama antibodies to make them more tolerable to humans. The hope of course is to create a vaccine against HIV that is well-tolerated and effective in humans.
McCoy LE, Rutten L, Frampton D, Anderson I, Granger L, et al. (2014) Molecular Evolution of Broadly Neutralizing Llama Antibodies to the CD4-Binding Site of HIV-1. PLoS Pathog 10(12): e1004552. doi:10.1371/journal.ppat.1004552