嗜水气单胞菌灭活疫苗对虹鳟免疫力和抗病力的影响

Effects of inactivated Aeromonas hydrophila vaccine on immunity and disease resistance of Oncorhynchus mykiss

为研究嗜水气单胞菌(Aeromonas hydrophila)灭活疫苗对虹鳟(Oncorhynchus mykiss)(250 g±12 g)免疫力和抗病力的影响,给试验鱼腹腔注射0.2 mL的灭活嗜水气单胞菌悬液(1.0×108cfu/mL)。分别在注射前(0 d)和注射后7、14、21、28、35、42 d取样,测定血液白细胞吞噬活性、血清溶菌酶(LZM)活力、补体C3含量以及头肾和脾脏中IgM、IgT基因表达情况。结果表明:注射嗜水气单胞菌疫苗能显著提高白细胞吞噬率(PP)和吞噬指数(PI)、LZM活力和补体C3含量,注射后21 d达峰值,PI、LZM和补体C3在42 d仍显著高于对照组。免疫后21 d头肾和脾脏中IgM基因上调表达,35 d达峰值(分别上升24倍和26倍),42 d下降但仍极显著高于对照组。头肾和脾脏中IgT的上调表达比IgM弱得多,头肾35 d达峰值(上升6.2倍),脾脏28 d达峰值(上升6.1倍)。免疫42 d后嗜水气单胞菌攻毒结果表明,嗜水气单胞菌灭活疫苗对虹鳟有较高的免疫保护作用,免疫保护率达到71.43%。

In order to study the effects of inactivated Aeromonas hydrophila vaccine on the immunity and disease resistance of Oncorhynchus rnykiss, each fish was intraperitoneally （i. p. ） injected with 0. 2 mL vaccine （1.0 ×10^8 cfu/mL）, con-trol group was i. p. injected with same volume of physiological saline. Fish was sampled before （0 d） and after vaccina-tion （7, 14, 21, 28, 35, 42 d）. Blood leucocytes phagocytosis, serum lysozyme （LZM） activity, complement C3 content, head kidney and spleen IgM, IgT gene expression were assayed. Results showed that the vaccine enhanced phag- ocytic percentage （PP）, phagocytic index （PI）, LZM activity and complement C3 significantly. The IgM in head kidney and spleen rose on 21 d, peaked on 35 d （24 times and 26 times higher respectively）, and decreased on 42 d but still sig-nificantly higher than control. The IgT up-regulation was weaker than IgM. The IgT peaked on 35 d （6.2 times higher） in head kidney and peaked at 28 d （6.1 times higher） in spleen. Fish was challenged by A. hydrophila on 42 d after vaccina-tion. The challenge result showed that the inactivated A. hydrophila vaccine exerted high immune protection effect, and the protective rate cowld reach 71.43%.