A COMPARATIVE-STUDY OF CONGENITAL AND POSTNATALLY ACQUIRED HUMAN CYTOMEGALOVIRUS-INFECTION IN INFANTS - LACK OF EXPRESSION OF VIRAL IMMEDIATE-EARLY PROTEIN IN CONGENITAL CASES

Postmortem tissues from infants with congenital and postnatally acquir ed human cytomegalovirus (HCMV) infection were examined by routine his tology, immunohistochemistry (IHC) and in situ hybridization (ISH) to determine the dynamics of viral replication in vivo. Histologically, i nfants in both groups showed characteristic inclusion-bearing cells mo st commonly in lung, kidney, liver and pancreas. IHC for late proteins using a rabbit polyclonal antibody and ISH for viral genomes detected most-of the infected cells as nuclear and/or cytoplasmic signals. How ever, immunostaining with a monoclonal antibody against viral immediat e early (IE) proteins was variable depending on the stage of viral rep lication within an individual infected cell. In tissues of infants wit h postnatal HCMV infection, many cells harboured IE antigens, while in tissues from congenital cases most of the affected cells lacked IE an tigens and only a few showed cytoplasmic staining. The difference was not caused by the antigenic diversity among viral strains as confirmed by in vitro study. Our findings suggested that congenital infections exhibited uniformly late stage proteins with inactive viral replicatio n at death, while acquired ones remained active. The different viral a ctivity may reflect the immune status of congenital and acquired HCMV infections.