Studies on infectious mononucleosis. II. Attempts at experimental transmission to monkeys.

Heparinized blood specimens obtained from two patients in the acute phase of infectious mononucleosis and from a healthy technician were injected intravenously into rhesus monkeys (Macaca mulatta) and the animals were observed for three weeks to one month for clinical, hematological and serological signs of infectious mononucleosis.Splenomegaly was the only definite clinical finding after 12 and 16 days, respectively. There were no definite hematological changes.At autopsy, hyperplasia of the germinal centres of lymphoid follicles, occasional foci of lymphocytic infiltration in the red pulp, and abnormal lymphoid cells in venules or arteries of the spleen were noted.The lesions in the spleen suggest that asymptomatic, presumably viral, infections occur in rhesus monkeys after inoculation with material from patients with infectious mononucleosis.