Epidemiology of rhesus rhadinovirus and retroperitoneal fibromatosis herpesvirus at the California National Primate Research Center

Both the epidemiology and natural history of rhesus rhadinovirus (RRV) and retroperitoneal fibromatosis herpesvirus (RFHV) were explored in three studies conducted with samples collected from large socially housed groups of rhesus macaques at the California National Primate Research Center.;Animals were selected using systematic sampling techniques from three randomly selected half-acre corrals. Antibody testing was performed with a rhadinovirus immunofluorescence assay while nucleic acid amplification was performed using real-time PCR assays specific for each virus. Of the 90 animals tested 88 were rhadinovirus antibody positive and 2 were indeterminate. Prevalence of RRV and RFHV in either or both blood and saliva samples was 81% (73/90) and 44% (40/90) respectively. RRV and RFHV are both highly endemic in the breeding population of rhesus macaques at the CNPRC and co-infections are common.;The longitudinal study was composed of quarterly sampling of blood and saliva samples over an 18 month period from the same group of 90 animals selected for the cross sectional study. Age, season and corral location were analyzed as possible determinates of viral shedding in saliva or viremia as well as the amount of virus in each sample type. Both age and season significantly affected both the presence and amount of RRV and RFHV in samples, and the statistical model developed allowed us to examine multiple variables in one model.;The tissue distribution study was performed on 9 animals selected at random from the available tissues in the pathogen detection laboratory tissue bank. Both RRV in situ hybridization (ISH) as well as RRV and RFHV real-time PCR were performed on the tissue blocks selected. Likely due to the latent nature of rhadinovirus infection the level of both viruses in normal tissues was below the threshold of ISH detection. Some positive tissues were detected although only weak staining was observed and results were not reproducible. This failure of detection limited our ability to study viral cell tropism but these findings are consistent with those observed with the homologous human virus Kaposi's sarcoma herpesvirus (KSHV) also known as human herpesvirus 8 (HHV-8) in human tissues.