Serological evidence for variation in the incidence of herpesvirus infections in different species of apes.

Sera from captive lowland gorillas, chimpanzees, orangutans, and gibbons were screened by enzyme-linked immunosorbent assay (ELISA) for antibody to herpesviruses serologically related to human herpes simplex virus types 1 and 2 (HSV-1, HSV-2), a baboon virus (SA8), and a macaque herpesvirus (B virus). The incidence of herpesvirus antibodies varied considerably among the different species, gorillas having the highest incidence of seropositivity (65.4%) and orangutans the lowest. The virus specificity of positive sera was further analyzed by examining the kinetics of virus neutralization, competition of reactivity in ELISAs, and immunoblotting against HSV-1, HSV-2, SA8, and B virus antigens. Using these assays, the majority of positive gorilla sera (49 of 53, 92%) were determined to react in a manner identical to human HSV-1 immune sera. The remaining four positive gorilla sera reacted as HSV-2-positive sera. In contrast, the majority of positive chimpanzee sera (5 of 7, 71%) reacted as HSV-2 immune rather than HSV-1 immune. All positive sera from gibbon apes reacted as HSV-1 positive. No orangutan sera were identified which gave positive reactions by ELISAs to any of the four primate herpesviruses tested. Although four orangutan sera gave equivocal results against HSV-1 antigen, further analysis by immunoblotting could not confirm any specific reactivity with any of the primate herpesvirus antigens. Varied reactivity among individual animals with both SA8 and B virus proteins was observed, but none of the seropositive primates detected appeared to be infected with either of these simian viruses. Three gorilla sera had antigen recognition patterns slightly different from those of HSV-2-positive human and chimpanzee sera and another HSV-2-positive gorilla serum, raising the possibility that these animals harbor an indigenous virus related to HSV-2.