RECIPROCAL INTERACTIONS BETWEEN HUMAN CYTOMEGALOVIRUS AND HUMAN T-CELL LEUKEMIA-LYMPHOMA VIRUS TYPE-I IN MONOCYTE-DERIVED MACROPHAGES CULTURED IN-VITRO

Infection of macrophages with human cytomegalovirus (HCMV) has been sh own to be nonlytic and exclusively cell associated. Human T cell leuke mia-lymphoma virus type I (HTLV-I) is capable of establishing producti ve infection in macrophages, We studied the interactions between HCMV and HTLV-I in monocyte-derived macrophages cultured in vitro. We found that coinfection of macrophages with HCMV and HTLV-I significantly en hanced HCMV replication, resulting in release of infectious HCMV from dually infected cells. On the other hand, HCMV inhibited HTLV-I replic ation in macrophages coinfected with both viruses. Reciprocal interact ions between HCMV and HTLV-I were mediated by their trans-acting prote ins. Results of transfection studies demonstrated that the tax gene pr oduct of HTLV-I alone was capable of upregulating HCMV production. In a transient gene expression assay the immediate-early 2 (IE2) protein of HCMV alone could inhibit HTLV-I replication, whereas the IE1 protei n, which had no effect by itself, produced a synergistic inhibitory ef fect together with the IE2 protein. Results from this study suggest th at in vivo double infection of macrophages with HCMV and HTLV-I may co ntribute to the dissemination of HCMV infection in patients suffering from HTLV-I-associated T cell leukemia-lymphoma.