CLONING AND CHARACTERIZATION OF AN EIMERIA-ACERVULINA SPOROZOITE GENEHOMOLOGOUS TO ASPARTYL PROTEINASES

A lambda ZapII cDNA library was constructed using mRNA from Eimeria ac ervulina sporulated oocysts and screened with monoclonal antibodies ra ised against Eimeria tenella sporulated oocysts. Monoclonal antibody N 3C8B12 identified a clone (6S2) potentially encoding an aspartyl prote inase since significant homology with cathepsin D, pepsin and renin pr oteinases was revealed by sequence comparisons. The 1500-bp cDNA fragm ent containing the coccidial gene was subcloned into pGEX-FA expressio n vector, leading to the production of an 80-kDa fusion protein (FA6S2 ) which was used to immunize rabbits. The anti-FA6S2 rabbit sera revea led a single 43-kDa protein present in Eimeria acervulina, Eimeria ten ella, Eimeria maxima and Eimeria falciformis sporulated oocyst antigen s. Indirect immunofluorescence and electron microscopy with mAb N3C8B1 2 localized the putative aspartyl proteinase in the refractile bodies of Eimeria tenella sporozoites.