Abstract
The suppression of T[thymus derived] cell DNA synthesis by serum from mice acutely infected 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. Untracentrifugation of serum from mice acutely infected with MCMV removed most of the virus and abrogated the inhibition of DNA synthesis. In 2 of 4 experiments, serum from mice 4-5 wk postinfection did not contain infectious MCMV but did suppress. MCMV itself can suppress DNA synthesis of T cells; however, this may not be the exclusive mechanism of suppression exerted by serum from MCMV-infected mice.