约氏黄杆菌减毒活疫苗对鳜免疫效果评价

为获知约氏黄杆菌(Flavobacterium johnsoniae)减毒活疫苗(M170株)浸泡免疫鳜(Siniperca chuatsi)后的免疫应答,采用荧光定量RT-PCR方法测定免疫后鳜肝脏溶菌酶(Lys)基因、脾脏免疫球蛋白(Ig M)基因表达动力学,并检测了血清中Lys活性和抗体效价变化规律。结果表明,约氏黄杆菌减毒活疫苗浸泡免疫后,鳜肝脏Lys基因表达量显著上调(P0.05),第48小时表达量达到峰值,是对照组的10.9倍(P0.05),直到第28天表达量仍显著高于对照组(P0.05)。同时免疫鱼血清Lys活性明显升高,第2天达到峰值,是对照组的4.35倍(P0.05),第6天与对照组水平相当;免疫鳜脾脏Ig M基因相对表达量从第7天开始上调并显著高于对照组(P0.05),至第28天其相对表达量为对照组的98.7倍(P0.05);而免疫鱼血清抗体效价在第7天开始高于对照组,第28天达到峰值(26)。免疫后第28天采用强毒株M168进行攻毒,结果显示,免疫组相对成活率显著高于对照组,其相对免疫保护率(relative percentage survival,RPS)达85.9%。结果表明约氏黄杆菌减毒株M170可引起鳜特异性和非特异性免疫应答,并提供良好的免疫保护效果。

Immune response of mandarin fish (Siniperca chuatsi) to attenuated Flavobacterium johnsoniae vaccine

To study the immune response of mandarin fish (Siniperca chuatsi) to attenuated Flavobacterium johnsoniae strain M170,we used fluorescence quantitative RT-PCR method for determination of liver lysozyme (Lys) gene in spleen,gene expression dynamics of immunoglobulin (IgM),and detected the changes of the Lys activity and the antibody titer in serum.The results show that after the F.johnsoniae attenuated accine immunization,the Lys gene expression in liver increased significantly (P ＜ 0.05),reaching the peak at the 48thhour,10.9 times higher than that of the control group (P ＜0.05),and had been higher than the control group significantly until the 28th day (P ＜ 0.05).Meanwhile,the Lys activity in serum increased significantly,reaching the peak on the 2nd day,4.35 times higher than that of the control group (P ＜ 0.05) and was equivalent to the level of the control group on the 6th day.The relative expression of IgM gene from mandarin fish spleen began to increase and had been significantly higher than that of the control group since the 7th day (P ＜ 0.05),98.7 times higher than that of the control group until the 28th day (P ＜ 0.05).The antibody titer in the immune fish serum was higher than that of the control group significantly since the 7th day (P ＜0.05),reaching the peak (26) on the 28th day.On the 28th day after immunization,the strain M168 was used to attack the virus,and the relative survival rate of the immunized group was higher than that of the control group significantly,and the relative percentage survival (RPS) was 85.9％.The resuits show that the specific and non-specific immune response can be induced by attenued F.johnsoniae M170 and provide good protection for mandarin fish.