Release of sporozoites from Eimeria oocysts/sporocysts is an essential step in the intracellular development of the parasite in its host. Little is known about this process except that elevated temperature (∼ 40 °C) plus trypsin and bile salts are required for sporozoite to escape from sporocysts. In this study, it was found that adding a reducing agent, either dithiothreitol (DTT) or Tris(2-carboxyethyl)phosphine hydrochloride (TCEP), increased the lifespan of sporozoites released from Eimeria maxima. While the addition of DTT or TCEP affected the apparent molecular weight of trypsin, it did not interfere with excystation of E. maxima, but rather had a positive effect on the number of viable sporozoites present after release. This effect was time-dependent in that the number of intact sporozoites at 15 and 30 min after excystation was similar between untreated and DTT- or TCEP-treated sporocysts. However, by 45–60 min, virtually no sporozoites were observed in excystation fluid not containing DTT or TCEP. Of interest is that this effect appeared to be Eimeria species-dependent. Eimeria acervulina and E. tenella sporozoites remained viable for at least 60 min after excystation in the absence of DTT or TCEP. The effect of DTT and TCEP on chymotrypsin was also studied with all 3 Eimeria species because there is some evidence that chymotrypsin is an effective excystation enzyme. Indeed, E. maxima sporozoites excysting from sporocysts with chymotrypsin in the presence of DTT or TCEP remained viable for at least 60 min after release, unlike excystation done in the absence of these reducing agents. Chymotrypsin was capable of excysting E. acervulina in the presence or absence of DTT or TCEP. Of interest, is that chymotrypsin was ineffective in the excystation of E. tenella. These findings suggest that trypsin and chymotrypsin have differential effects on sporozoite excystation and that reducing agents may alter sites on the enzyme that affect sporozoite viability, but not release from sporocysts.

从艾美球虫卵囊/孢子囊中释放子孢子是宿主体内寄生虫细胞内发育的重要步骤。除了需要高温（约40°C）加上胰蛋白酶和胆盐以使子孢子从孢子囊逸出外，对这一过程了解甚少。在这项研究中，发现添加还原剂二硫苏糖醇（DTT）或盐酸三（2-羧乙基）膦（TCEP）可以增加从最大艾美球虫释放的子孢子的寿命。虽然添加DTT或TCEP会影响胰蛋白酶的表观分子量，但它不会干扰大肠埃希菌的兴奋。，但对释放后存在的活子孢子数量有积极影响。这种作用是时间依赖性的，因为未经处理的和经DTT或TCEP处理的孢子囊在运动后15和30分钟时完整的子孢子数量相似。但是，到45-60分钟，在不含DTT或TCEP的激发流体中几乎没有观察到子孢子。令人感兴趣的是，这种效应似乎与艾美球虫属有关。在没有DTT或TCEP的情况下，激进后的艾美球虫和tenella孢子虫在存活至少60分钟后仍能存活。DTT和TCEP对胰凝乳蛋白酶的作用也用所有3种艾美球虫进行了研究因为有一些证据表明胰凝乳蛋白酶是一种有效的兴奋酶。实际上，在存在DTT或TCEP的情况下，用胰凝乳蛋白酶从孢子囊中膨出的大肠埃希氏菌子孢子在释放后至少可存活60分钟，这与不存在这些还原剂的兴奋作用不同。在存在或不存在DTT或TCEP的情况下，胰凝乳蛋白酶能够将大肠埃希氏菌囊化。有趣的是，胰凝乳蛋白酶在大肠杆菌的诱变中无效。这些发现表明，胰蛋白酶和胰凝乳蛋白酶对子孢子兴奋有不同的作用，还原剂可能会改变酶的位点，从而影响子孢子的生存能力，但不会从孢子囊中释放出来。