Enzyme variation and pathogenicity of recent field isolates of Eimeria tenella.

Seventy isolates of Eimeria tenella, obtained from commercial poultry farms worldwide and four reference laboratory strains were characterised by studies on the electrophoretic mobility of up to three enzymes. All populations possessed the same electrophoretic form of lactate dehydrogenase and malate dehydrogenase and one of two forms of glucose phosphate isomerase. One isolate was characterised by both forms of glucose phosphate isomerase. Studies on several isolates indicated that there was no correlation between the form of glucose phosphate isomerase found and the pathogenicity of an isolate.