Quantitative PCR assays reveal high prevalence of lymphocryptovirus as well as lytic phase gene expression in peripheral blood cells of cynomolgus macaques

Lymphocryptoviruses such as Epstein-Barr virus (EBV) are important pathogens in both human and non-human primates, particularly during immunosuppression. Immunomodulatory molecules that may suppress antiviral immunity are commonly tested in the cynomolgus macaque. To enable the study of lymphocryptovirus (LCV) in this non-clinical model, PCR-based assays were developed to measure LCV viral load, as well as transcripts for the lytic phase LCV gene, BALF-2. Results from studies employing these assays showed that LCV genome was detected in the oropharyngeal epithelium of all cynomolgus monkeys tested, and the majority had viral genome in peripheral blood mononuclear cells (PBMCs). The results also revealed LCV lytic phase gene expression not only in the oropharynx of most monkeys, but also in PBMCs of approximately one half of monkeys tested. This unexpected finding suggests that initiation of the lytic gene expression cascade occurs often in the peripheral blood cells of healthy monkeys.