Diagnosis of cytomegalovirus infection by detection of the early antigen of cytomegalovirus in cell cultures.

Conventional virus isolation and detection of cytomegalovirus (CMV) early antigen by immunofluorescence staining of cultured cells were compared in the diagnosis of CMV infection from urine specimens. By virus isolation, 33 specimens out of 333 studied were positive, and the mean length of culturing time for a positive result was 23 days (range from 6 to 45 days). By early antigen detection, 35 specimens were positive after 20 hours in culture, but the number of positive findings increased to as high as 49 after 7 days in culture. It is recommended that, in addition to the early antigen staining after one day in culture, cells should also be stained after one week in culture, because the sensitivity is essentially improved by extended culturing time.