PERSISTENT RAT VIRUS-INFECTION IN JUVENILE ATHYMIC RATS AND ITS MODULATION BY IMMUNE SERUM

In contrast to euthymic juvenile rats, which develop acute, self-limit ing infection with rat virus (RV), RV infection of juvenile athymic ra ts was persistent for up to 12 weeks as demonstrated by recovery of in fective virus, transmission to cagemates, and detection of viral DNA i n the lungs. Administration of RV antiserum at the time of virus inocu lation prevented persistent infection in five of six rats. Among rats given RV antiserum 1 week after virus, the interval at which euthymic rats begin to seroconvert, RV was not detected 1 week later but was re covered from four of six rats 3 weeks later. Results of these studies confirm that T-cell deficiency facilitates persistent RV infection and indicate that antibody provides significant protection from persisten t infection only if it is present at the time of virus inoculation. Th e results support the concept that factors which prevent persistent in fection in euthymic rats act early after virus inoculation and may inc lude cellular immunity.