Lymphoid cell infection by measles virus in newborn hamsters. Role for monocytes in virus spread to distant sites

Following intraperitoneal inoculation of measles (HBS) virus into newborn hamsters widespread but variable productive lymphoid tissue infection was detected by a sensitive viral isolation technique. Peritoneal wash cells and spleen were the most common sites of infection. Virus was frequently isolated from the bone marrow and was commonly found in multiple lymph nodes. Thymic infection was only rarely demonstrated. A mononuclear cell associated viremia was demonstrated by Ficoll-hypaque fractionation of peripheral blood from animals receiving both high- and low-dose virus. Infection was present in both plastic adherent and non-adherent fractions of the blood mononuclear cells. The infected cell population in the spleen had both nylon wool and plastic adherent characteristics and infection was therefore thought to be macrophage-associated. The possible relevance of such macrophage associated infection is discussed with regard to the pathogenesis of natural measles infection and the immunosuppression observed in measles-infected hosts.