THE INTRACELLULAR-LOCALIZATION OF HUMAN CYTOMEGALOVIRUS DNA IN PERIPHERAL-BLOOD LEUKOCYTES DURING ACTIVE INFECTIONS BY HIGH-RESOLUTION FLUORESCENCE IN-SITU HYBRIDIZATION

Although viremia is an integral part of the pathogenesis of human cyto megalovirus (HCMV) disease, the interaction between HCMV and circulati ng leukocytes of actively infected patients remains an area of uncerta inty. It is still a matter of dispute, whether leukocytes support vira l replication with subsequent production of infectious virus. In a new approach we developed and applied a sensitive fluorescence in situ hy bridization assay for the precise intracellular localization of HCMV g enomes in leukocytes. It was shown that in vivo HCMV genomes were excl usively localized in the cytoplasm of leukocytes, indicating that the majority of these cells are virus carriers or abortively infected. Tho ugh this method easily detects single copy genes in metaphase chromoso mes, the number of HCMV DNA positive leukocytes was significantly lowe r than the number of HCMV pp65 antigen positive cells. In relation to the pp65 antigen positive cells, only 1-4% of these cells were DNA pos itive. In addition, the much lower frequency of HCMV immediate early a ntigen positive leukocytes in comparison to the pp65 antigen positive cells and the impossibility of detecting other viral antigens support the hypothesis that the origin of pp65 found in leukocytes results mai nly from protein uptake.