Role of viremia in the suppression of T-cell function during murine cytomegalovirus infection.

The suppression of T-cell deoxyribonucleic acid (DNA) synthesis by serum from mice acutely with murine cytomegalovirus (MCMV) was investigated. Spleen cells from uninfected mice were exposed to concanavalin A in the presence of serum taken from mice at various times after infection with MCMV. The capacity of the serum to suppress DNA synthesis first appeared at day 3 postinfection and was associated with free infectious virus. Addition of MCMV to serum from uninfected mice also suppressed DNA synthesis. Ultracentrifugation of serum from mice acutely infected with MCMV removed most of the virus and aborgated the inhibition of DNA synthesis. However, in two of four experiments, serum from mice in weeks 4 and 5 postinfection did not contain infectious MCMB but did suppress. Therefore, it appears that MCMV itself can suppress DNA synthesis of T cells; however, this may not be the exclusive mechanism of suppression exerted by serum from MCMB-infected mice.