Severity of diarrhea in rotavirus-infected wild-type and 5-HT3 receptor KO mice. (A) Percentage of KO pups and wild-type pups with diarrhea on day 2 (*, P = 0.012), which is the time point when the most severe diarrhea occurs in infant mice. (B) Number of mean diarrhea days in KO and wild-type mice (*, P = 0.03). (C) The mean number of diarrhea episodes in wild-type and KO pups show that there were fewer diarrhea episodes in the KO pups (P = 0.07). Wild-type mice, n = 18; KO mice, n = 27. Data are expressed as mean with SEM. (A) Fisher’s exact test; (B and C) Mann-Whitney test.