Enzyme-linked immunosorbent assay and indirect haemagglutination techniques for measurement of antibody responses to Eimeria tenella in experimentally infected chickens.

An indirect haemagglutination test (IHA) and ELISA technique were developed to detect antibodies against Eimeria tenella. The ELISA technique was relatively easy to perform, more sensitive than the IHA test, and needed only a fraction of the antigen required for IHA. The highest titers using ELISA were 1:16,384 compared to the IHA titers of 1:64 for the same sera. The ELISA titers depended upon the age of the birds when they were infected, the number of oocysts inoculated and the number of inoculations. Immunodeficient birds (cyclophosphamide-treated), when inoculated with several doses of oocysts of E. tenella (350, 3,000, 30,000) showed no IHA or ELISA antibody titers. The immuno-competent chickens of the same age, which received identical doses of oocysts responded with readily detectable antibody levels. Chickens inoculated with E. maxima or E. necatrix had sera titers of 1:50 or 1:400, respectively, when reacted with E. tenella antigen. The E. tenella inoculated birds had titers as high as 1:3,200 with the same antigen.