Murine cytomegalovirus infection in the spleen and its relationship to immunosuppression.

An attempt was made to correlate murine cytomegalovirus-induced immuno-suppression with the presence of virus-infected cells in the spleen. For this purpose, SWR/J mice were infected with murine cytomegalovirus, and spleens were removed periodically and assayed for the presence of infectious centers in different cell populations and for their capacity to respond to mitogens. The maximal degree of immunosuppression correlated with the peak in adherent cell infectious centers. This was followed by a rapid rise in the number of cells per spleen (splenomegaly), a more gradual return to normal responsiveness to mitogens, and a rapid disappearance of infectious centers. These results add more support to the hypothesis that murine cytomegalovirus-induced immunosuppression is caused indirectly by infection of adherent spleen cells.