Expression and localization of an S100 protein-like molecule in Eimeria tenella

We investigated the expression of a calcium-binding protein, the S100 prote in, in Eimeria tenella. Cecal paraffin sections from experimentally infecte d chickens were treated with anti-alpha-S100 (anti-alpha subunit of S100 pr otein) and anti-beta-S100 (anti-beta subunit of S100 protein) monoclonal an tibodies and anti-S100 whole molecule polyclonal antibody. The avidin-bioti n peroxidase method was used for immunocytochemical staining. Our results d emonstrated a positive immunoreaction within the schizonts, macrogametes, a nd oocysts. These stages were all beta subunit and S100 whole-molecule posi tive. Immunoblot studies of the total proteins of E. tenella merozoites and sporozoites of the original strain and 2 precocious lines have demonstrate d that precocious attenuation produced different S100 protein isotypes.