Host-parasite interactions of apicomplexan parasites with their vertebrate hosts

顶复门寄生虫与其脊椎动物宿主的宿主-寄生虫相互作用

• 批准号: 106453-2007
• 负责人: Barta, John
• 金额: $ 2.84万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2007
• 资助国家: 加拿大
• 起止时间: 2007-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=363127
• 关键词: Host; parasite; interactions; apicomplexan; parasites

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.

许多顶复门寄生虫（如疟疾、弓形虫和球虫）具有重要的兽医、农业和医学意义。艾美耳球虫正在对商业家禽（尤其是鸡）的盈利饲养带来持续的严峻挑战。加拿大家禽业每年因球虫病造成的药物成本和生产损失损失数亿美元。针对球虫的活疫苗是可能的，但由于许多艾美耳球菌属的免疫学上不同的菌株以及肠道的改变而使鸡容易患细菌性疾病（特别是坏死性肠炎），从而使情况变得复杂。我们有不同的大艾美耳球品系，它们彼此相似，但不会对鸟类进行交叉免疫（尽管它们相似，但它们不能防止第二种品系的攻击）。这些巨型艾美球菌菌株之间存在的微小差异必定是保护性免疫反应的重要目标。将继续在分子水平上对这些菌株进行解剖，以鉴定每个菌株中的独特分子，这些分子可能代表鸡用来保护自己免受攻击的免疫学重要抗原；一旦独特的分子被分离出来，这个假设就会得到检验。这对于产生针对球虫的无活性疫苗至关重要。  其次，当鸟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。为了解决肉鸡活疫苗的局限性（因为肠道环境的改变会促进严重的细菌性肠炎），将测试益生菌（从鸡中分离出的无害、有益的共生细菌）在活球虫疫苗接种过程中保护鸟类肠道的能力。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料药物的依赖。最后，在其他工作中，我们希望更好地了解顶复门所有寄生虫之间存在的进化关系。除了更好地了解我们的生物世界之外，描述鲜为人知的寄生虫将为我们提供一种方法来预测新出现的寄生虫病的可能生命周期、潜在宿主和可能的药物敏感性。