Cytomegalovirus DNA can be detected in peripheral blood mononuclear cells from all seropositive and most seronegative healthy blood donors over time.

BACKGROUND: A poor correlation between cytomegalovirus (CMV) seroreactivity and the risk of CMV transmission prompted an investigation of the presence of CMV DNA in peripheral blood mononuclear cells (PBMNCs) from seropositive and seronegative blood donors. Because latent CMV exists in monocytes, monocyte-enriched cells were analyzed separately. STUDY DESIGN AND METHODS: Samples from 270 blood donors were tested with a sensitive polymerase chain reaction (PCR) test that detects two CMV genes, and the results were correlated to CMV serology. Cross-reactivity with other herpesvirus genes was not recorded.
RESULTS: PCR testing demonstrated that 71 percent of seropositive donors harbor CMV in PBMNCs. Thus, not all seropositive donors were CMV DNA positive when individual samples were tested. Tests repeated over a period of time showed that all seropositive individuals were positive. Increased sensitivity was obtained with enriched monocytes. Among seronegative donors, 55 percent harbored CMV DNA in monocyte-enriched PBMNCs, while 14 percent had CMV DNA in PBMNCs.
CONCLUSION: All seropositive donors harbored latently infected PBMNCs, as demonstrated by the testing of samples collected over time. In addition, a substantial proportion of seronegative individuals are CMV carriers and might transfer infection. The findings concur with clinical evidence of CMV transmission by blood components from seronegative individuals and with in vitro reactivation of CMV in PBMNCs from seronegative donors.