The prevalence, transmission, and variation of simian foamy viruses (SFVs) in baboons was investigated. Over 95% of adult baboons in the breeding colony as well as recently imported adult animals had high titers of anti-SFV serum IgG. Maternal antibody was detectable in infants' serum up to 6 months of age. Approximately 30% of infants in breeding harems experienced SFV infections by 1 year of age. Shedding of SFV in oral secretions was common, with 13% of samples from normal adult animals and 35% from immunosuppressed animals containing infectious SFV. SFV was isolated from three baboon subspecies (olive, yellow, and chacma baboons) and sequences from both the pol and the LTR regions of the provirus were amplified by PCR and sequenced. Phylogenetic analysis indicated that all baboon isolates formed a single lineage distinct from SFVs of other African monkey species. Within the baboon SFV lineage, two distinct clades were apparent, which consisted of isolates from yellow and olive baboons and isolates from chacma baboons. Competition ELISAs indicated that, while SFV isolates of these two groups were very closely related, antigenic differences do exist between them. SFV isolates from a drill and a mandrill were distinct from baboon SFV isolates, both genetically and antigenically.

Biochemical and immunological properties of structural and non-structural polypeptides of the human simplex viruses (HSV1 and HSV2) and four related herpesviruses of non-human primates [Herpesvirus simiae (B virus), H. cercopithicus (SA8), H. saimiri 1 (HVS 1), and H. ateles 1 (HVA 1)] were compared. Using a radioimmunoassay (RIA), the presence of antigenic determinants shared among all six viruses was demonstrated. The relative degree of antigenic cross-reactivity among these viruses was further assessed by competition RIA. Antigenically, HSV 1 and HSV 2 were most closely related to each other although both SA 8 and B virus were also very closely related to HSV 1. Considerably less cross-reactivity existed between either HVS 1 or HVA 1 and the other four primate herpesviruses. Cross-hybridization between simian and human herpesvirus genomes demonstrated that extensive homology exists between each of the simian viruses and both HSV1 and HSV 2. Viral polypeptides bearing common antigenic determinants were identified by immune precipitation of infected cell polypeptides and by immunoblotting. Among the polypeptides of HSV which were recognized by antisera to simian viruses were the VP 5 and p40 proteins, both of which are structural components of the virion nucleocapsid. Using recombinant plasmids containing sequences of the HSV 1 VP5, p40, DNA polymerase, major DNA binding protein, and TK enzyme genes, homologous sequences were detected in all four simian viruses. Together, these results demonstrate that HSV 1, HSV 2, SA 8, and B virus form a closely related sub-group of the primate herpesviruses; HVS 1 and HVA 1 are also related to the other four primate herpesviruses, albeit more distantly.

The antigenic relatedness of the surface glycoprotein antigens of six herpesviruses indigenous to human and nonhuman primates was examined. Binding of anti-viral sera to viral antigens expressed on the surface of infected cells demonstrated that the surface antigens of herpes simplex virus type 1 (HSV 1), HSV 2, simian agent 8 (SA8), and Herpesvirus simiae (B virus) exhibit extensive cross-reactivity. Surface antigens of two viruses isolated from South American primates, H. saimiri 1 (HVS 1) and H. ateles 1 (HVA 1), were comparatively more virus-specific in their antigenic reactivity. Endpoint neutralization tests performed in the presence and absence of complement confirmed these results. Immunoprecipitation of viral proteins was used to identify those representing cross-reactive surface antigens. A glycoprotein of approximately 110,000-125,000 Daltons (110-125 k) was immunoprecipitated from cells infected with each of the six primate herpesvirus by antisera to each of the viruses. Using monospecific antisera, these glycoproteins were shown to be antigenically related to the gB glycoproteins of HSV. Although these glycoproteins were antigenically conserved among all six viruses, antibodies to the gB glycoproteins did not cross-neutralize heterologous viruses. A glycoprotein of approximately 60-70 k was precipitated from HSV 1, HSV 2, SA8, and B virus infected cells by antisera to each of these four viruses. These SA8 and B virus glycoproteins were shown to be antigenically related to the gD glycoproteins of HSV 1 and HSV 2 and to be involved in cross-neutralization among these viruses. Antisera to HVS 1 and HVA 1 did not recognize these gD glycoproteins nor was a glycoprotein of similar molecular weight precipitable from HVS 1 or HVA 1 infected cells by antisera to the other four viruses. Southern blot hybridizations using probes for HSV glycoprotein genes confirmed the conservation of the gB glycoproteins among all the simian viruses and of the gD gene in SA8 and B virus. A glycoprotein of approximately 75-80 k was, however, precipitated from HVS 1 and HVA 1 infected cells by antisera to either of these two viruses. In addition, at least one glycoprotein which appeared to be predominantly virus-specific in its reactivity was identified for five of the viruses.

Summary This study reports the complete genome sequence of chimpanzee herpesvirus (ChHV), an alphaherpesvirus isolated from a chimpanzee. Although closely related to human herpes simplex virus type 2 (HSV2), the level of sequence diversity confirms that ChHV is sufficiently distinct to be considered a member of a different virus species rather than a variant strain of HSV2. Phylogenetic comparison with other simplexviruses at several levels supports the hypothesis that HSV2 and ChHV co-evolved with their respective human and chimpanzee hosts and raises questions regarding the evolutionary origins of HSV1.

Although both beta-and gammaherpesviruses indigenous to great-ape species have been isolated, to date all alphaherpesviruses isolated from apes have proven to be human viruses [herpes simplex virus types 1 (HSV1) and 2 (HSV2) or varicella-zoster virus]. If the alphaherpesviruses have co-evolved with their host species, some if not all ape species should harbour their own alphaherpesviruses. Here, the isolation and characterization of an alphaherpesvirus from a chimpanzee (ChHV) are described. Sequencing of a number of genes throughout the ChHV genome indicates that it is collinear with that of HSV. Phylogenetic analyses place ChHV in a clade with HSV1 and HSV2, the alphaherpesviruses of Old World monkeys comprising a separate clade. Analysis of reactivity patterns of HSV2-immune human sera and ChHV-immune chimpanzee sera by competition ELISA support this relationship. Phylogenetic analyses also place ChHV rather than HSV1 as the closest relative of HSV2.