Neonatal infection with mouse thymic virus: spleen and lymph node necrosis.

Mouse thymic virus (TA) is a naturally occurring herpesvirus of laboratory and wild mice, which produces massive thymic necrosis when inoculated into newborn mice. Our histopathological study showed necrosis not only of the thymus but also of the spleen and lymph nodes which was noticeable by day 7 and complete by day 14. Both spleen and lymph nodes regenerated to an almost normal histological pattern by day 70. The results show that TA infects multiple lymphoid tissues causing massive necrosis in all, and is not limited to a single site, the thymus. TA infection was found to be a persistent herpesvirus infection in both the lymph nodes and spleen. During the period of acute infection, as necrosis increased, the response of cell suspensions of lymph nodes to the T cell mitogens concanavalin A and phytohaemagglutinin was virtually non-existent. Activity returned to normal as the histological repair progressed.