对虾白黑斑病的病原病因研究

STUDIES OF PATHOGENY OF WHITE AND BLACK SPOT DISEASE ON PENAEID SHRIMP

对虾白黑斑病是养殖中国对虾的常见病，曾被怀疑是细菌性疾病。本试验通过对病虾肝胰腺、血液和病灶组织的细菌分离，对正常虾用自黑斑病虾投喂感染，与病虾共栖感染以及用分离于病虾的细菌注射感染等一系列试验发现：细菌或其它生物性病原与对虾白黑斑病并无直接关系。通过对病虾的酚氧化酶活力测定．血细胞的观察和流行病学研究．分析认为该病是由于对虾长期营养不良在应激状态下所引发的一种生理性疾病。腹部每节两侧基部和尾肢等部位出现的病灶──白班或黑斑是在对虾处于应激状态下，酚氧化酶诱导相关基质山酚到醌最终产生黑色素形成的。此外还讨论了相关基质的来源以及与对虾应激反应有关的几项因素。

White and black spot disease of penaeid shrimp was one of serious diseases on shrimpfarming of China. In this study, bacteria were isolated from hepatopancreas, blood and focous of diseaseshrimp. Healthy shrimps were infected artificially by injecting bacteria from diseased shrimps,fed with fresh diseased shrimps,and stocking them with diseased shrimps together or in the water taken formdiseased shrimp pond.The results showed that there's no direct relationship between white and blackspot disease of shrimp and bacteria or other pathogen. Based on the results of measurements ofphenoloxidase activities in diseased shrimp blood and observation of diseased shrimp blood, we considerthat white and black spot disease is a kind of physiological deficiency disease, which was caused bylong term malnutrition and high temperature press of culture water(>30℃). The focus, white andblack spot appeared mainly on base of each segement of abdomen and tail, etc., was caused byaccumulated melanin,the end product of a series of chemical reactions.These reactions begin withactivation of prophenoloxidase located inside shrimp shells, and further the enzyme catlysys substratesfrom blood producing quinones and eventually melanin.