CMV DNA is rarely detected in healthy blood donors using validated PCR assays

Although serologic screening or WBC reduction of blood components can reduce the incidence of transfusion-transmitted CMV (TT-CMV) infection, 'breakthrough' cases of TT-CMV still occur and may produce serious sequelae. NAT of blood components for CMV DNA has been proposed to further reduce the risks of TT-CMV. However, large-scale studies to determine the utility of validated CMV NAT assays for donor screening have not been reported.

Coded whole-blood samples (n=1000) were tested for the presence of CMV DNA using two CMV PCR assays previously validated in a multicenter trial (a nested PCR assay directed at the CMV UL93 open-reading frame and the Roche Monitor assay). Corresponding plasma samples were tested in parallel for the presence of anti-CMV using other assays (Abbott CMV EIA and Fujirebio/Olympus CMV particle agglutination assays).

In total 416 and 514 of the samples tested as CMV-seropositive and -seronegative, respectively, by both antibody assays. The remaining 70 samples had discrepant serology results. Only 2 of the 1000 samples (both seropositive) had reproducibly detectable CMV DNA (positive in at least three of four replicates). CMV DNA was not reproducibly detected in seronegative samples or in samples with discrepant serology results.

Although previous investigations showed frequent detection of CMV DNA in healthy CMV-seropositive (and some seronegative) blood donors, these studies were relatively small and the performance characteristics of their assays were difficult to evaluate. In contrast, the present large cross-sectional study of US donors utilized two previously validated PCR assays and demonstrated that CMV DNA is only rarely detectable in seropositive donors. Thus, the use of CMV PCR assays with optimal performance characteristics did not increase the detection of potentially infectious blood components beyond that provided by current serologic screening assays.