To determine whether the enhanced survival of Bid-deficient mice in comparison to wild-type mice following T3SA+ infection results from reduced reovirus replication, we compared titers of reovirus at sites of primary and secondary replication at 4, 8, and 12 d post-inoculation ( Figure 5B -E). Peak titers of reovirus were comparable or slightly higher (,5-to 10-fold) in the intestine, liver, and heart of wild-type mice in comparison to Bid-deficient animals. In contrast, substantially greater differences in peak reovirus titers were observed in the brain, with wild-type animals showing ,25-to 100-fold higher titers in comparison to those in Bid-deficient mice at 8 d post-inoculation. However, by 12 d postinoculation, titers of reovirus in wild-type and Bid-deficient mouse brains were equivalent. These findings suggest that reovirus infection is inefficient in the absence of Bid, especially in the CNS.