TISSUE RESISTANCE TRANSFER IN SCHISTOSCOME SNAILS

来自抗血吸虫的光滑双脐螺的变形细胞产生器官（APO）的同种异体移植物赋予易感螺对人类病原体曼氏血吸虫的后续挑战的抗性。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。该提议的工作假设是，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，并且这些抗性血细胞杀死入侵的孢子囊。将通过使用RAPD-PCR检查受体组织的供体多态性来检验这一假设。该技术还将允许描述供体细胞浸润到受体血淋巴中的时间过程，并将提供对血细胞寿命的见解。用荧光标记探针鉴定耐药钉螺死亡孢子囊周围肉芽肿中的血细胞。最后，另一种假设，即载脂蛋白O赋予耐药性的分泌“耐药因子”，将通过尝试被动转移耐药的蜗牛与载脂蛋白同种异体移植物注射到易感蜗牛的血浆进行测试。

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.