Thymic hypoplasia, splenomegaly and immune depression in guinea pigs with neonatal cytomegalovirus infection.

The effects of cytomegalovirus (CMV) infection on the spleen and thymus of neonatal guinea pigs were assessed. Guinea pigs with neonatally acquired CMV infection developed growth retardation, thymic hypoplasia and splenomegaly. Significant depletion of the T lymphocyte population occurred in the thymuses of these animals whereas inflammatory and immune proliferative responses were clearly evident in their spleens. Higher titers of infectious virus were recovered from the spleen than from the thymus. In addition, spleen cells from neonatally infected animals had significantly reduced proliferative responses to both the T-cell mitogen, concanavalin A, and the B-cell mitogen, lipopolysaccharide. Responses to concanavalin A were most severely impaired. These results point to the significant immunodepressive effect of acute CMV infection and to the dissimilar alterations induced by CMV in the spleen and thymus of acutely infected neonates.