Recognition of cytomegalovirus clinical isolate antigens by sera from cytomegalovirus-negative blood donors.

Background: The most common way to prevent transmission of CMV by blood transfusion is to use blood products from seronegative donors. Screening of blood donors for CMV infection is usually based on detection of antigens obtained from the CMV laboratory strain AD 169. Recent evidence suggests that approximately up to 20 percent of CMV-negative blood donors may in fact be CMV-DNA positive by PCR analyses.
Study Design and Methods: In this study, sera from CMV-seronegative, CMV-seropositive, and CMV-DNA-positive/seronegative individuals, and from patients with acute and convalescent CMV infection for detection of CMV antibodies were analyzed. CMV antigens prepared from cells infected with CMV clinical isolates or the CMV laboratory strain AD 169 in ELISA and Western blot assays were used.
Results: All CMV-positive sera from blood donors were seropositive for the CMV antigens prepared from AD 169 (A2) or from a CMV clinical isolate (C6). Interestingly, whereas all CMV-negative blood donors were negative in tests for the CMV antigen A2, 36 percent were CMV seropositive using the CMV antigen C6 in ELISA.
Conclusion: The data suggest that a substantial number of CMV-seronegative/CMV-DNA-positive serum samples contain antibodies that recognize CMV clinical isolate antigens.