Enzyme-Linked Immunosorbent Assay to Detect Antibody Response against Eimeria bovis and Eimeria zurnii in Calves

Abstract

In the United States, bovine coccidiosis is primarily a disease of young calves, 6 to 9 mo of age (Fitzgerald, 1975, Bovine Practice 10: 2833). Eimeria zurnii and Eimeria bovis are considered to be the 2 most pathogenic species of cattle (Levine and Ivens, 1970, The coccidian parasites [Protozoa, Sporozoa] of ruminants. University of Illinois Press, Urbana, Illinois). Early detection of the clinical coccidiosis before production of the oocysts, by means of serological methods, may be useful in identifying the infected animals, thereby enabling early and effective treatment. The enzyme-immunosorbent assay (ELISA) has been reported to be sensitive and effective in detecting the serum antibodies against chicken coccidiosis (Rose and Mockett, 1983, Parasite Immunology 5:479-489; Saatara Oz et al., 1984, Journal of Parasitology 70: 859-863). This led to the present investigation of cross-reactivity between a soluble antigen of Eimeria tenella and sera from calves infected with E. zurnii and/or E. bovis. Lack of species specificity might allow the use of a purified avian coccidia antigen to identify coccidiosis in cattle. Twenty Holstein calves were purchased at about 1 wk of age and maintained in indoor pens. Fecal samples were collected before and during the experiment. The calves had not produced oocysts of any species prior to oral inoculation. About 5 wk after purchase, they were divided into 4 groups and were inoculated orally with sporulated oocysts of E. bovis and/or E. zurnii as described below. Group A: 4 calves received 150,000 oocysts of E. bovis (95% pure). Group B: 4 calves received 230,000 oocysts of E. zurnii (78% pure). Group C: 6 calves received 300,000 oocysts of E. bovis and 500,000 oocysts of E. zurnii. Group D: 6 calves were kept as uninfected controls. Contaminating oocysts present were Eimeria auburnensis, Eimeria cylindrica, and Eimeria ellipsoidalis. Calves were bled via the jugular vein prior to inoculation and then weekly to 5 wk post-inoculation (4 wk PI for the E. bovis and E. zurnii group). All of the sera collected were stored at 20 C. Sixteen sera were randomly collected from colostrum-deprived calves that were not positive for coccidia on fecal exam (birth to 13 wk of age) and were used as additional uninfected control