Detection of Cryptosporidium-specific serum immunoglobulins in captive snakes by a polyclonal antibody in the indirect ELISA.

摘要

An indirect ELISA was developed to detect systemic Cryptosporidium-specific antibodies (Ab) in the serum of captive snakes. An optimum concentration of Cryptosporidium soluble protein-cocktail antigen was 20 鎔/ml. In a direct ELISA, alkaline phosphatase-labelled rabbit-anti-snake polyvalent Ab detected snake immunoglobulins at a dilution of 1:12 800. It was possible to detect Cryptosporidium-specific Ab at a serum dilution of 1:1 600. 19 of 26 (73%) captive snakes (8 species) were Cryptosporidium-seroconverted; however, the differences in Ab titre among species were not significant. The distribution of absorbance values did not conform to a normal distribution; mean Ab titre of 9 snakes with cryptosporidiosis was significantly higher than mean Abtitre of the remaining 10 snakes. The monoclonal Ab test showed that the stools of 17 (89%) of 19 seropositive snakes contained Cryptosporidium oocysts; 9 of those 19 (47%) stools were positive by acid-fast-stained (AFS) direct wet smear. A significantpositive relationship between Cryptosporidium-seroconversion and snake age was observed; the mean age of seropositive snakes was significantly higher than the mean age of seronegative animals. It is concluded that the developed assay is fast, reproducible, could be used for retrospective and prospective serological surveys, and assist ophidian centres in establishing Cryptosporidium-free collections. It is also suggested that, after standardization, the assay could be used for large-scale screening of captive snakes.