A chimpanzee rhadinovirus sequence related to Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8: increased detection after HIV-1 infection in the absence of disease.

OBJECTIVE: To look for a virus related to Kaposi's sarcoma-associated herpesvirus (KSHV) or human herpesvirus 8 (HHV8) in chimpanzees and to investigate phylogenetic and biological similarities to KSHV.
METHODS: Peripheral blood mononuclear cell (PBMC) DNA samples from chimpanzees (Pan troglodytes troglodytes) were screened with newly designed consensus oligonucleotide primers for the DNA polymerase gene of KSHV-related gamma2-herpesviruses (rhadinoviruses). Samples from HIV-1-infected and -uninfected chimpanzees were screened with virus-specific primers. Antibodies to KSHV structural and latent antigens were measured by immunofluorescence, enzyme-linked immunosorbent assay (ELISA) and Western blot.
RESULTS: We identified 972 base pairs (bp) of a new viral DNA polymerase sequence with 81.6% (nucleotides) and 93.2% (protein) identity to that of KSHV/HHV8. It was detected in 15/37 (41%) animals experimentally infected with HIV-1, but only in one out of 30 uninfected animals (P<0.001). Antibodies were found by immunofluorescence to structural, but not latent, KSHV antigens in nearly all HIV-1-infected and uninfected animals.
CONCLUSION: Like man and two other Old World primate species, chimpanzees harbour a virus closely related to KSHV/HHV8, termed Pan troglodytes rhadinovirus-1 (PtRV-1). Like KSHV, PtRV-1 is more easily detected by polymerase chain reaction (PCR) in the PBMC of HIV-1-infected than of HIV-1-uninfected individuals, suggesting increased viral load. Despite the close phylogenetic relationship and biological similarities between KSHV and PtRV-1, Kaposi's sarcoma (KS) has not been reported in HIV-1-infected chimpanzees. PtRV-1 may lack some of the pathogenic determinants of KSHV, or humans and chimpanzees may differ in how they control the infection with their respective rhadinoviruses.