To evaluate the pathogenicity and immunogenicity of Cryptosporidium(C) parvum isolated from mouse in Korea, we inoculated 2.5×10⁴ oocyets per mouse of it to 3∼10 week-old SPF mice and investigated body weight gains, oocyste sheddings, serum and coproantibody titers, pathological changes in the intestine and lung.
Desquamation of villi by the developments of oocysts in the small intestine was occured from 6 to 9 days after infection in the mice. It was supposed that the malabsorption due to this desquamation might induce the growth retardation. These results were distinet in the 3∼4 week-old mice than the 6∼7 or 9∼10 week-old mice.
Cryptoeporidial antibody levels were measured in serum and feces. of artificially infected mice. Antibody level reached peaks at 18 days in serum and 9 and 16 days in feces after infection. It was supposed that the developments of oocyets were inhibited by the antibody, and so the pathogenicity of C parvum was decreased.
Only the immunosuppressed mice were artificially infected in the lung. In this case, severe hyperemia, congestion and bronchopneumonia were observed characteristically. Hyperplasia, squamous metaplasia, degeneration, necrosis and desquamation of the brnachiolar epithelia were observed, and cryptosporidia were detected in the epithelial border, lamina propria and submucosa layer. Alveoli and bronchiolar lumen were filled with a lot of neutrophils, macrophages, desquamated epithelia and cryptosporidia.
The results suggest that the isolate of C parvum from mouse in Korea is moderately pathogenic and induce the antibody in blood and intestinal lumen
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