Localization of Eimeripain, an <i>Eimeria tenella</i> Cathepsin B-Like Cysteine Protease, during Asexual and Sexual Intracellular Development in Chicken Ceca

Abstract

Hemorrhagic diarrhea in poultry is caused by Eimeria tenella, the most pathogenic avian coccidian parasite, and new approaches to treat the disease are continually being sought. Although eimeripain, a cathepsin B-like cysteine protease from E. tenella, has recently been identified as a novel anticoccidial drug target, its localization during the intracellular development of parasites remains unclear. Here, we demonstrate the expression of eimeripain during asexual and sexual development of E. tenella in vivo. Promature eimeripain was detected only in the early immature second generation of schizonts. In contrast, the mature eimeripain was most strongly detected in the middle-sized immature second generation of schizonts. Both promature and mature eimeripain disappeared depending on the maturation level of second generation of schizonts, but were strongly expressed again in the third generation of schizonts. In the sexual stage, both promature and mature eimeripain were detected in the cytoplasm of micro- and macro-gametocytes and zygotes, but expression became weak in zoites forming oocysts. Collectively, our findings suggest that eimeripain might play a key role in the differentiation of intracellular zoites in the ceca and could be an interesting candidate to develop a novel, effective anti-coccidian drug.

F-actin distribution and function during sexual development inEimeria maxima

“…Accordingly, numerous microscopic and molecular approaches have been utilized over the last several decades to characterize the basic aspects of the developmental biology of maturing male (micro-) and female (macro-) gametocytes (Mehlhorn, 1971; Pittilo and Ball, 1979; Ferguson et al 2003). This research includes studies on the morphology and biochemical make-up of the two types of wall-forming bodies (Fried et al 1992; Belli et al 2002, 2004; Mouafo et al 2002; Frölich et al 2013) as well as the fine structure and biochemistry of the oocyst wall (Belli et al 2009; Mai et al 2009, 2011; Bushkin et al 2013, 2012; Katrib et al 2012; Rieux et al 2012; Matsubayashi et al 2014).…”