Evidence of infection with simian type D retrovirus in persons occupationally exposed to nonhuman primates

Simian type D retrovirus (SRV) is enzootic in many populations of Asian mon keys of the genus Macaca and is associated with immunodeficiency diseases. However, the zoonotic potential of this agent has not been well defined. Sc reening for antibodies to SRV was performed as part of an ongoing study loo king for evidence of infection with simian retroviruses among persons occup ationally exposed to nonhuman primates (NHPs). Of 231 persons tested, 2 (0. 9%) were found to be strongly seropositive, showing reactivity against mult iple SRV antigens representing gag, pol, and env gene products by Western i mmunoblotting. Persistent long-standing seropositivity, as well as neutrali zing antibody specific to SRV type 2, was documented in one individual (sub ject 1), while waning antibody with eventual seroreversion, was observed in a second (subject 2). Repeated attempts to detect SRV by isolation in tiss ue culture and by using sensitive PCR assays for amplification of two SRV g ene regions (gag and pol) were negative. Both individuals remain apparently healthy. We were also unable to transmit this seropositivity to an SRV neg ative macaque by using inoculation of whole blood from subject 1. The resul ts of this study provide evidence that occupational exposure to NHPs may in crease the risk of infection with SRV and underscore the importance of both occupational safety practices and efforts to eliminate this virus from est ablished macaque colonies.