Development of a heterologous model in germfree suckling rats for studies of rotavirus diarrhea

Abstract

Germfree suckling rats were infected with an SA11 rotavirus strain. Infected pups developed diarrhea associated with histopathological changes. The virus was detected in feces and in the small intestine. Cellular vacuolation was observed in the villi of the jejunum. These results provide a new model for further investigations of group A rotavirus infection.

FIG. 1

Percentage of rats delivering feces immediately upon gentle palpation. Rats were inoculated with either SA11 rotavirus (solid bars) or MEM as a control (open bars). An asterisk denotes a percentage of samples significantly different from that of the control group (P < 0.05 [χ² test]). Rats were infected at the age of 2 days (infected group, n = 35; control group, n = 20) (A), 5 days (infected group, n = 34; control group, n = 25) (B), or 8 days (infected group, n = 23; control group, n = 16) (C).

FIG. 2

Relative viral antigen load/virus concentration ratio determined in feces of infected pups. Rats were inoculated at the age of 2 (A), 5 (B), or 8 (C) days. Feces were sampled and assayed for rotavirus antigens by ELISA. A standard curve obtained from the viral inoculum was determined for each plate. The viral antigen load in feces was determined conventionally relative to the standard curve. Data represent individual values obtained for fecal specimens.

FIG. 3

Histological aspects of jejunum villi of germfree suckling rats examined on day 3 p.i. Five-day-old rats were inoculated with either SA11 rotavirus (A) or MEM as a control (B). Intestinal sections were polychromatically stained and observed by light microscopy. Magnification, ×300.

FIG. 4

Detection of rotavirus antigens in jejunum cells of germfree suckling rats 3 days p.i. Five-day-old rats were inoculated with either SA11 rotavirus (A) or MEM as a control (B). Rotavirus structural proteins were labeled with a hyperimmune rabbit antirotavirus serum and then a goat anti-rabbit immunoglobulin-fluorescein isothiocyanate. Rotavirus antigens were detected under UV light by immunofluorescence. Magnification, ×400.