Oocysts appeared to develop normally and formed large numbers of sporozoites. However, closer examination of these sporozoites revealed that they were of abnormal shape and some 2030% smaller in size. Each sporozoite possessed a single enlarged, protruding area associated with the position of the nucleus. The position of these protrusions varied between sporozoites from being located at the posterior end to being positioned near the middle of the sporozoite.The mutant sporozoites accumulated in the hemolymph and did not invade the salivary glands. Gliding motility was strongly reduced. Mutant sporozoites were able to attach normally to the glass surface and undergo circular gliding, but their gliding speed was fivefold slower than that of wild type sporozoites.Inoculation of purified oocyst-derived/hemolymph sporozoites into mice did not result in infection of the mice.

Inoculation of purified oocyst-derived/hemolymph sporozoites into mice did not result in infection of the mice.