EIMERIA MAGNA - PATHOGENICITY, IMMUNOGENICITY AND SELECTION OF A PRECOCIOUS LINE

A precocious line (PrEmag) of Eimeria magna in rabbits was obtained by selecting for early development of oocysts. The prepatent period was shortened by 46 h. The pathogenicity of PrEmag was substantially reduc ed and its reproductive potential was much lower (500 times) than that of the parent strain. Rabbits given 2500 oocysts of PrEmag were almos t totally protected against a challenge with the parent strain. As in other precocious fines of coccidia from the rabbit, PrEmag showed morp hological anomalies of the sporulated oocysts. Each sporocyst harboure d one large refractile body instead of the two smaller ones in the par ent strain.