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.