Detection of DNA, mRNA and early antigen of the human cytomegalovirus using the immunomax technique in autopsy material of children with intrauterine infection

The present study focuses on the immunomax technique in association with the avidin-biotin-peroxidase complex (ABC) technique and a non-isotopic variation of in situ hybridisation (ISH) for optimal microscopical detection of human cytomegalovirus (HCMV). The studies were performed on an archival paraffin material originating from five children deceased due to intrauterine infection. The results of immunocytochemical and hybridocytochemical studies, with or without amplification using biotinylated tyramine, were compared with the routine histopathological results and results obtained using the polymerase chain reaction (PCR). Early antigen (EA)-HCMV was demonstrated in approximately twice as many cells as detected in the routine staining and also in cells that seemed morphologically intact. The hybridocytochemical studies confirmed the presence of HCMV DNA in cells that were positive in the immunocytochemical tests and, in addition (using the ISH-immunomax technique), in cell nuclei of intact myocardial myocytes. In general, fewer cells manifested the presence of HMCV mRNA than the presence of HCMV DNA. The immunomax technique was found to be more sensitive than the techniques of classical immunocytochemistry or of ISH. The former technique permitted the documentation of a higher number of HCMV replication sites than could be detected using the latter techniques. However, the clinical course of HCMV infection or the cause of death of the children was not directly related to the intensity of HCMV expression in tissues.