B-cell epitope mapping within the MA16 antigenic sequence found in Eimeria acervulina merozoites and sporozoites

Overlapping heptapeptides derived from the MA16 Eimeria acervulina antigenic sequence (Castle et al., 1991) were synthesised on polypropylene pins ('pepskan' technique, Cambridge Research Biochemicals, UK). Binding of antibodies from chickens and rabbits infected and immunised respectively with various species of Eimeria oocysts (E. acervulina, E. tenella, E praecox, E. necatrix and E. maxima), was examined using the coated pins as the solid phase of an enzyme immunoassay (EIA). Antigenicity of the overlapping synthetic heptapeptides was then analysed using a number of algorithms based on the amino acid sequence to predict secondary protein structure, hydrophilicity, acrophilicity and chain flexibility profiles. The antigenicity of this sequence appears to be quite different from that found for the E. tenella GX3264 antigenic sequence (Bhogal et al., 1992) whose profile was similarly examined (Talebi and Mulcahy, 1994) using the same rabbit and chicken anti-Eimeria oocyst sera.