Potential of in situ hybridization for early diagnosis of productive cytomegalovirus infection.

In situ hybridization with a probe specific for immediate-early genes was used for detection of cytomegalovirus (CMV) transcripts in peripheral blood mononuclear cells, and the potential use of this technique as a diagnostic tool was assessed. The results were compared with those obtained with conventional assay systems. In 8 of 18 continually observed patients who developed a productive CMV infection, a high number of hybridization-positive cells were observed 1 to 2 weeks before the conventional tests yielded positive results. Thus, quantitative evaluation of hybridization results provided an early and specific marker for beginning CMV infection or reactivation. In three cases, quantitative in situ hybridization assays provided the only laboratory marker indicating CMV infection or reactivation. It was also found that a probe specific for immediate-early genes was superior to a probe specific for late genes for diagnosis of productive infections.