Antibody responses and capacity of adoptively transferred immune splenocytes to clear enteric MNV infection. (A) Levels of serum anti-MNV IgG antibody determined by ELISA (1:100 serum dilution) in mock- and MNV-immunized wild-type B6 mice 35 to 42 days postinfection. (B) Virus titers in the distal ileum of persistently infected RAG1−/− mice 6 days after transfer of medium alone, nonimmune splenocytes, or immune splenocytes. These data are pooled from three independent experiments with three to five mice per group in each experiment. **, P < 0.0001; *, P < 0.05. LD, limit of detection.