Abstract：
Serpins are a protein superfamily of serine protease inhibitors. One of their functions is to participate in immune responses by inhibiting the activation of prophenoloxidase. To elucidate the immune role of serpin in Macrobrachium nipponense, a serpin gene (Mnserpin) was cloned from M. nipponense in this study. Mnserpin protein has an N-terminal signal peptide and a serpin domain that contains a hinge region, a signature sequence of serpin and a P1(arginine)-P1\' scissile bond, and evolutionally closely related to the crustacean serpins. Mnserpin highly expressed in the hepatopancreas and gill. Mnserpin expression increased first and then decreased after Vibrio parahaemolyticus and Aeromonas hydrophila infection, and was knocked down by dsMnserpin injection with a maximum knockdown efficiency of 92 %. Mnserpin knockdown increased the expression of the clip domain serine protease and prophenoloxidase genes and phenoloxidase activity of M. nipponense as well as its mortality rate after V. parahaemolyticus and A. hydrophila infection. The recombinant Mnserpin (rMnserpin) showed bacteria-binding and bacteriostatic activity in vitro. Moreover, rMnserpin injection decreased the bacterial number and the mortality rate of M. nipponense post V. parahaemolyticus and A. hydrophila infection. These results suggested that Mnserpin plays a major role in the innate immune response of M. nipponense.
摘要：
Serpin是丝氨酸蛋白酶抑制剂的蛋白质超家族。它们的功能之一是通过抑制酚氧化酶原的激活来参与免疫应答。为了阐明serpin在日本沼虾中的免疫作用，在这项研究中，从日本M.nipponense克隆了serpin基因（Mnserpin）。Mnserpin蛋白具有N端信号肽和含有铰链区的serpin结构域，serpin的签名序列和P1（精氨酸）-P1\'断裂键，在进化上与甲壳类昆虫密切相关。Mnserpin在肝胰腺和g中高度表达。Mnserpin表达在副溶血性弧菌和嗜水气单胞菌感染后先升高后降低,并通过dsMnserpin注射击倒，最大击倒效率为92％。Mnserpin敲除增加了夹域丝氨酸蛋白酶和酚氧化酶原基因的表达以及日本M.nipponense的酚氧化酶活性，以及副溶血性弧菌和嗜水菌感染后的死亡率。重组Mnserpin（rMnserpin）在体外显示出细菌结合和抑菌活性。此外，rMnserpin注射可降低副溶血性弧菌和嗜水性弧菌感染的细菌数量和死亡率。这些结果表明，Mnserpin在日本M.nipponense的先天免疫反应中起着重要作用。
