TISSUE RESISTANCE TRANSFER IN SCHISTOSCOME SNAILS

同种异体移植来自抗血吸虫光滑生物钉螺的变形细胞产生器官(APO)，使易感钉螺对随后的人类病原体曼氏血吸虫攻击具有抵抗力。然而，这种适应性抗性转移的机制，以及在更基本的水平上APO的正常功能，尚不清楚。这一提议的工作假设是，移植的APO在受体蜗牛中产生表型抗性血细胞，从而形成血细胞嵌合体，这些抗性血细胞比杀死入侵的孢子囊。这一假设将通过使用随机扩增-聚合酶链式反应检查受者组织中供体的多态来检验。这项技术还将描述供体细胞渗透到受者血淋巴的时间过程，并将提供对血细胞寿命的洞察。利用荧光标记的探针，对转移抗性钉螺灭活孢子囊周围的肉芽肿内血细胞进行鉴定。最后，另一种假说，即APO通过分泌“抗性因子”来赋予抵抗力，将通过将APO同种异体移植的蜗牛的血浆注入易感蜗牛来被动转移抵抗力，以检验这一假说。

Allografts of the amebocyte producing organ (APO) from schistosome- resistant Biomphalaria glabrata snails confer resistance to a subsequent challenge with the human pathogen Schistosoma mansoni in susceptible snails. However, the mechanism for this adaptive transfer of resistance, and at a more fundamental level the normal function of the APO, are not known. The working hypothesis for this proposal is that the transplanted APO produces phenotypically resistant hemocytes in the recipient snail, thereby forming a hemocyte chimera, and these resistant hemocytes than kill invading sporocysts. This hypothesis will be tested by examining recipient tissues for donor polymorphisms with the use of RAPD-PCR. This technique will also allow description of the time course of infiltration of donor cells into the recipient's hemolymph, and will provide insights on hemocyte lifespan. With the use of fluorescently labeled probes, identity of hemocytes in granulomas surrounding killed sporocysts in snails with transferred resistance. Finally, an alternative hypothesis, that the APO confers resistance by secreting "resistance factors," will be tested by attempting to passively transfer resistance from snails with APO allografts by injecting their plasma into susceptible snails.