Eight cesarean-derived goat kids were inoculated with caprine arthritis-encephalitis virus (CAEV), and proliferative responses of their peripheral blood mononuclear cells to mitogens and CAEV antigen were monitored for 9 months. Antibody specific for CAEV was measured by an enzyme-linked immunosorbent assay. Five cesarean-derived noninfected goats were tested simultaneously. Significant differences between the infected and control mononuclear cell proliferation reactions to CAEV began 14 days post-inoculation and continued in a fluctuant manner until 134 days post-inoculation. The magnitude of the proliferative reaction steadily increased in infected goats until the end of the experiment at 271 days post-inoculation. Responses to mitogens were not significantly different between infected and control goats. Virus-inoculated goats produced CAEV-specific antibody that reached a maximum level between 49 and 77 days post-inoculation and then declined to lower levels through 271 days post-inoculation. The virus-inoculated goats developed mild but characteristic clinical evidence of caprine arthritis-encephalitis, and CAEV was reisolated from four goats at 286 days post-inoculation. The five control goats developed neither an anti-CAEV immune response nor clinical disease, and CAEV could not be reisolated from them.