Four 3-week-old germ-free piglets were orally infected with a dose of rotavirus that caused severe diarrhea from 24 hpi in 3-week-old gnotobiotic piglets [32] . For practical reasons, three uninfected germ-free piglets were slaughtered at the zero time point (mock, see Table 1 ). In order to isolate highquality RNA from jejunal mucosal scrapings, infected piglets were slaughtered 12 and 18 hpi. Thus, 12 and 6 h before severe diarrhea would have been induced. In three of the four infected animals, rotavirus was detected in their feces. Determination of the percent dry matter showed that only the fecal samples collected 18 hpi (piglets 65 and 67) had a significantly lower (pasty) consistency [18] . This indicated that not all of the piglets developed diarrhea before 12 hpi, and that the two piglets slaughtered 18 hpi did not develop the severe form of diarrhea normally observed at 24 hpi [32] . In jejunal tissue sections prepared from these two 18-h piglets, villus length was decreased to two-thirds of the average length measured in corresponding sections prepared from the three control piglets. No significant differences in crypt depths were observed between infected and control animals. For both piglets that were slaughtered at 18 h, these results indicated that the orally applied rotavirus reached the Transcriptional response to rotavirus 1313 jejunum and induced the desired limited (not severe) pathological symptoms. In addition, the lower concentration of lymphocytes in the blood indicated that the animals were effectively infected with rotavirus [47] .