Eimeria brunetti:Selection and characteristics of a precocious (and attenuated) line

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Abstract
A line of Eimeria brunetti with an abbreviated life cycle (i.e. a ‘precocious’ line) was obtained by repeated selection for the first oocysts to be passed during an infection in chickens. The precocious line, when compared with the parent strain, was characterised by a significant attenuation of virulence, reduced output of oocysts and an endogenous development in which third‐generation schizonts were almost completely eliminated. However, despite the loss of asexual stages, the immunogenicity of the precocious line was not different from that of its parent strain. A sub‐line obtained from a single oocyst isolated after 27 generations of selection was further serially passaged using oocysts recovered during the peak of the patent period. The sub‐line remained significantly attenuated after nine passages.