Host-parasite interactions of apicomplexan parasites with their vertebrate hosts

许多顶端复合体寄生虫(如疟疾、弓形虫和球虫)具有严重的兽医、农业和医学重要性。艾美耳球虫继续对商业家禽(尤其是鸡)的有利可图的饲养构成严重挑战。在加拿大，药物费用和球虫病造成的生产损失每年给家禽养殖业造成数亿美元的损失。针对球虫的活疫苗是可能的，但由于许多艾美耳球虫的免疫特性不同的菌株以及肠道的变化而使其复杂化，这可能使鸡容易患细菌性疾病(特别是。坏死性肠炎)。我们有不同的巨型埃希氏菌株系，它们彼此相似，但不能交叉免疫禽类(尽管它们相似，但它们不能抵御第二种株的挑战)。这些极大E.Maxima菌株之间存在的少数差异肯定是保护性免疫反应的重要目标。这些菌株将继续在分子水平上进行解剖，以确定每个菌株中可能代表免疫重要抗原的独特分子，鸡用这些抗原来保护自己免受挑战；一旦分离出独特的分子，这一假设将得到验证。这对于产生不可行的球虫疫苗至关重要。其次，当禽类感染一种寄生虫菌株，然后用第二种菌株攻击时，将检查鸟类的免疫反应。为了解决活疫苗在肉鸡中的局限性(因为肠道环境的改变会导致严重的细菌性肠炎)，将测试益生菌(从鸡身上分离出来的无害、有益的共生菌)在活球虫疫苗接种期间保护禽类肠道的能力。如果得到证实，这种方法可以从根本上减少我们对目前用于控制肉禽寄生虫的饲喂药物的依赖。最后，在其他工作中，我们希望更好地了解存在于蜂门所有寄生虫之间的进化关系。除了更好地了解我们的生物世界，对鲜为人知的寄生虫的特征将为我们提供一种方法来预测可能的生命周期、潜在的宿主和对新出现的寄生虫病病原体的可能的药物敏感性。

Many of apicomplexan parasites (such as malaria, Toxoplasma and coccidia) are of serious veterinary, agricultural and medical importance. Eimeria are continuing and serious challenges to profitable rearing of commercial poultry (especially chickens). Medication costs and production losses from coccidiosis cost the poultry industry several $100 million each year in Canada. Live vaccines against coccidia are possible but are complicated by immunologically distinct strains of many Eimeria species and alteration to the intestinal tract that can predispose chickens to bacterial disease (esp. necrotic enteritis). We have distinct lines of E. maxima that are similar to one another but do not cross-immunize birds (they do not protect against challenge with the second strain despite their similarity). The few differences that exist between these E. maxima strains must be important targets of a protective immune response. The strains will continue to be dissected at the molecular level to identify unique molecules in each strain that may represent immunologically important antigens that the chickens use to protect themselves against challenge; this hypothesis will be tested once the unique molecules have been isolated. This is critical for the generation of non-viable vaccines against coccidia.  Second, the immune responses of birds will be examined when infected with one strain of the parasite and then challenged with the second strain. To address the limitations of live vaccines in broiler chickens (because of an altered gut environment that promotes serious bacterial enteritis), probiotic bacteria (harmless, beneficial commensal bacteria isolated from chickens) will be tested for their ability to protect the intestinal tract of birds during live coccidial vaccination. If proven, this method could radically reduce our reliance on in-feed drugs currently employed to control these parasites in meat birds. Finally, in other work, we hope to better understand the evolutionary relationships that exist among all parasites of the phylum Apicomplexa. In addition to better understanding our biological world, characterizing poorly known parasites will give us a way to predict likely life cycles, potential hosts and possible drug sensitivities for agents of emerging parasitic disease.