Watch the Monkeys: Screening for New Retrovirus Outbreaks

Jeffrey Laurence, M.D., and Rowena Johnston, Ph.D.

August 2008—Retroviruses, the family of virus to which HIV belongs, have been present in humans for millions of years. In fact, fragments of ancient retrovirus infections remain in our genes to this day. Similarly, other primates have also been living—and evolving—with retroviruses for eons. In some cases these infections are harmless in one species but can cause disease or even death when transmitted to another species. For example, the devastating HIV pandemic arose primarily from chimpanzees, in whom the infection is essentially harmless. amfAR fellow Dr. Brandon Keele, working at the University of Birmingham in Alabama, recently described his work with another retrovirus that infects both monkeys and humans. He suggested how it might serve as an early warning system for future human infections of simian origin.

Writing in the July issue of PLoS Pathogens, Dr. Keele and colleagues describe how they conducted the first comprehensive sampling of chimpanzees for infection with the simian foamy virus SFVcpz. They examined fecal samples from more than 700 chimps in equatorial Africa; infections were noted in 44 to 100 percent of chimpanzees in the various animal communities surveyed.

Although there is no foamy virus specific to humans, people are susceptible to SFV infection via several species of monkey. Indeed, occupational exposures in zookeepers and hunters of monkey “bushmeat” are quite common, with SFV transmitted primarily through saliva. Fortunately, no obvious disease appears to result. Although human-to-human spread of SFV has not yet been documented, SFV has been found in commercial sex workers and blood donors in Africa.

These studies may be helpful to HIV research because there have been documented cases in both monkeys and humans of concurrent infection with SFV and AIDS viruses. Their combined effects are unknown. Once inside the body, individual simian foamy viruses can mix genetically, creating novel virus strains with the potential for new characteristics. Learning more about the biology of this virus is critical as SFV has been proposed as a building block in the design of AIDS vaccines to carry HIV proteins. In addition, as Dr. Keele and colleagues conclude, “SFVs are of public health interest because people in sub-Saharan Africa are routinely exposed to these viruses in the context of primate bushmeat hunting,” similar to their exposure to, and acquisition of, HIV via chimpanzees. “Thus, human SFVcpz infection should be formally investigated [as] a sentinel for ape-derived pathogens, including new ... HIV-1 outbreaks.”

Dr. Laurence is amfAR’s senior scientific consultant. Dr. Johnston is amfAR’s vice president of research.