An Experimental Rotaviral Enteritis Model with Neonatal Pigs

The Colostrum-Deprived, Artificially Reared Neonatal Pig as a Model Animal for Studying Rotavirus Gastroenteritis

“…In several of the reports mentioned, the concentration of rotavirus in the inocula was not always given but in those in which concentration was mentioned [8, 13,17,[19][20][21][22], it varied between lo6 and 10' rotavirus particles per pig. In a few studies in which rotaviruses were propagated by cell culture, the titer of the inocula used was 3.2 x lo4 TCIDSo/mL (tisssue culture infective dose) [12] or lo7 PFU/mL (plaque-forming units)[ 161.…”

“…Refined experimental procedures used in our rotaviral gastroenteritis research during the past 2 years have provided additional detailed information, particularly on the extent of anorexia, severity of diarrhea, and magnitude of fecal virus shedding, as well as on the effect of rotaviral infection on growth and mortality rate during the postinoculation period. The detailed experimental protocol including a description of the scales used for feces scores and agglutination scores used to assess fecal rotavirus shedding has been previously reported [22]. Under our experimental conditions, the onset of diarrhea occurred within 48 h after virus ingestion, profuse diarrhea lasted for at least 5 days (from 2 to 7 days postinoculation), and diarrhea progressively ceased thereafter (Figure 1 a).…”

“…In several experiments carried out in our laboratory, colostrum-deprived pigs reared under similar conditions and infected by 5 to 6 days of age with the same source of rotavirus at doses between lo6 and lo7 rotavirus particles have shown mortality rates between 40% and 50% by the end of the experimental periods (10 to 12 days postinoculation) (2 1 ; Gomez, unpublished results); lowering the rotavirus dose to lo5 or lo4 has reduced the mortality to 10% and 20% (Gomez, unpublished results). Increasing the dose of rotavirus to 8.4 x lo8 resulted in a cumulative mortality of 70%, with most of the mortality (45% from 15% to 60%) occurring between 6 and 8 days after virus ingestion [22].…”

“…Rotavirus infection depressed lactase-specific activity in the duodenal mucosa of children [69] as well as in the jejunal and ileal mucosa of pigs [13,16,[20][21][22]661. The decrease in jejunal and ileal lactase-specific activity at 7 and even 13 days postinoculation found in our recent study (Table 2, Gomez et al, unpublished results) confirms these reports.…”

“…In our most recent studies, pigs have been inoculated with rotavirus at 5 or 6 days of age. Human rotavirus isolates obtained from human infants with acute gastroenteritis [7, 8, 10, 11, 13, 15, 171, porcine rotavirus isolates [12,14,17,[19][20][21][22], and calf and foal rotaviruses [15] have been used as inocula to infect pigs. The source of rotavirus inocula that we have been using is a stock of bacteria-free fecal supernatant obtained from intestinal contents collected from rotavirus infected pigs as described by Lecce et al [29].…”