Researchers have identified a gene in Asian macaques that helps prevent infection by HIV-like lentiviruses.

The gene, TRIM5-CypA, produces a protein that is a fusion between two existing proteins-TRIM5 and CypA. TRIM5 binds to viruses related to HIV and destroys them while viruses use the CypA protein to shield themselves from the host cell, said Medical School professor Shawn P. O’Neil, one of the authors of the study.

Because the CypA protein attracts HIV-like viruses and the TRIM5 protein destroys them, the fused protein “might be able to target lentiviruses.”

The Harvard University Medical School researcher’s estimate of when this hybrid gene appeared in the monkey’s genome suggests that lentiviruses have been around for longer than previously believed.