Identification of Sporozoite Surface Proteins and Antigens of Eimeria nieschulzi (Apicomplexa)

Sodium dodecyl sulfate polyacrylamide gel electrophoresis, immunoblotting, lectin binding, and ¹²⁵I surface labeling of sporozoites were used to probe sporozoites of the rat coccidian, Eimeria nieschulzi. Analysis of silver stained gels revealed >50 bands. Surface iodination revealed about 14 well labeled, and about 10 weakly labeled but potential, surface proteins. The most heavily labeled surface proteins had molecular masses of 60, 53–54, 45, 28, 23–24, 17, 15, 14, 13, and 12 kD. Following electrophoresis and Western blotting, 2 of the 12 ¹²⁵I labeled lectin probes bound to two bands on the blots, which collectively indicated that two bands were glycosylated. Concanavalin A (ConA) specifically recognized a band at 53 kD, which may represent a surface glycoprotein, and a lectin derived from Osage orange (MPA) bound to a single band at 82–88 kD, that may also be a surface molecule. Immunoblotting using sera collected from rats inoculated orally with oocysts, as well as sera from mice hyperimmunized with sporozoites, revealed that many surface molecules appear to be immunogenic.