Venkataraman et al. focused their work on retrocyclin, a member of the defensin family of proteins. Defensins are made by all primates and have potent anti-microbial activity. Retrocyclin was recently shown to strongly inhibit HIV entry into human cells by blocking the interaction of viral proteins with their cellular receptors. Unfortunately, although the retrocyclin protein is found in Old World monkeys and orangutans, it is not present in humans (or gorillas and chimps), even though we have the retrocyclin gene.

That's because the human retrocyclin gene contains a mutation, known as a “nonsense mutation,” that prevents the production of the encoded protein....(cont)