Fig. 3

Protein secretion during invasion by eimerian sporozoite and merozoite. a Sporozoites must navigate the gut lumen until they reach the enterocytic niche with specific receptor(s) such as BCL2-AIEPU for attachment and which in turn stimulate protein secretion and host SG, which are known to function in the secretion of MICs. At the site of invasion, sporozoites first attach to the enterocytes with a sequence of events including formation of MJ and PVM accompanied by protein secretion. AMA2/RON5 contribute to MJ formation as RBs add to the array of acidic protein secretions. b For merozoites, RON4/AMA1 are particularly involved in MJ formation and MICs, ROPs ans proteinase play important roles during the process. Nonetheless, the complexes (AMA-1 and RON4) and (AMA-2 and RON5) may suffice for distinction between swift short-lived merozoites and long-ranging sporozoites. Unlike sporozoites with considerable motility, merozoites invade enterocytes fiercely and locally. The proteins involved during Eimeria invasion are quite different from other Apicomplexa [156] probably because of different host cell receptors and Eimeria's extensive migration in host gut. BCL2-AIEPU: associated athanogene 1 and endonuclease polyU-specific-like receptors; SG: surface glycan