为了解(鱼师)鱼诺卡氏菌全肽聚糖(WPG)对鱼类的免疫效应,应用1% (鱼师)鱼诺卡氏菌WPG溶液对乌鳢进行腹腔注射,在注射后第0、1、2、3、4、5、6、7、8天对乌鳢血液、黏液、肝脏、头肾组织进行取样,测定血细胞吞噬指数(PI)、血清替代途径补体活力(ACH50)以及组织中酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、超氧化物歧化酶(SOD)、溶菌酶(LSZ)活力等非特异性免疫相关指标。同法等量注射0.7%灭菌生理盐水作为对照。此外,通过攻毒试验测定 (鱼师)鱼诺卡氏菌WPG对感染 (鱼师)鱼诺卡氏菌乌鳢的免疫保护效应。结果表明:与对照组相比,试验组红细胞和白细胞PI及血清ACH50在注射后第1天就显著或极显著升高(P<0.05或P<0.01),并分别在注射后第2天、第2天和第1天达到峰值,峰值分别为2.45%、3.64%和306.67 unit/mL。试验组血清中LSZ和AKP活力分别从注射后第3天和第4天开始显著或极显著高于对照组(P<0.05或P<0.01),而血清中ACP和SOD活力则在注射后第1~7天均显著或极显著高于对照组(P<0.05或P<0.01)。注射 (鱼师)鱼诺卡氏菌WPG后,黏液、肝脏、头肾中ACP活力均有升高现象,达峰值时间分别为第2天、第4天、第7天;黏液和头肾中AKP活力在各时间点均无显著变化(P>0.05),肝脏中AKP活力仅在第3天、第4天出现显著或极显著升高(P<0.05或P<0.01);肝脏和头肾中SOD活力在各时间点均无显著变化(P>0.05),而黏液中SOD活力在各时间点均显著或极显著升高(P<0.05或P<0.01);黏液和肝脏中LSZ活力在第1天就显著或极显著升高(P<0.05或P<0.01),在第2天均达峰值,而头肾LSZ活力呈现逐渐升高再降低的变化趋势,仅在第5天表现出显著升高(P<0.05)。 (鱼师)鱼诺卡氏菌攻毒试验结果显示, (鱼师)鱼诺卡氏菌WPG腹腔注射免疫7、21、35 d后对乌鳢的保护率分别为35%、55%、60%。以上结果说明, (鱼师)鱼诺卡氏菌WPG对乌鳢血细胞PI、血清ACH50及组织中ACP、AKP、SOD、LSZ活力具有明显的调节作用,但调节作用的强弱存在组织差异性; (鱼师)鱼诺卡氏菌WPG腹腔注射免疫21 d以上对乌鳢诺卡氏菌病有明显的保护作用。

In order to research the immune effects of whole peptidoglycan (WPG) from Nocardia seriolae for fish, the non-specific immune indices such as haemocytes phagocytic index (PI), serum alternative complement pathway activity (ACH50), and superoxide dismutase (SOD), acid phosphatase (ACP), alkaline phosphatase (AKP) and lysozyme (LSZ) activities in different tissues of Channa argus were determined by injection with 0.3 mL/tail 0.1% solution of WPG from N. seriolae intraperitoneally. The C. argus injected 0.3 mL/tail 0.7% sterilized saline as a control. The samples, including serum, mucus, liver and head kidney, were taken from fish on day 0, 1, 2, 3, 4, 5, 6, 7 and 8 post-injection. Moreover, the immune protective efficacy of WPG from N. seriolae against N. seriolae in C. argus was measured by the challenge experiment. The results showed as follows: compared with the control group, the erythrocytes PI, leucocytes PI and serum ACH50 in trial group were significantly increased on day 1 (P<0.05 or P<0.01) and then got the peak on day 2, 2 and 1, which were 2.45%, 3.64% and 306.67 unit/mL, respectively. In serum, the AKP and LSZ activities in trial group were significantly increased from day 4 and 3 (P<0.05 or P<0.01), respectively, and the ACP and SOD activities were all significantly increased from day 1 to day 7 compared with the control group (P<0.05 or P<0.01). After injection WPG from N. seriolae, the activity of ACP in mucus, liver and head kidney was all increased and then got the peak on day 2, 4 and 7, respectively; no significant difference was found in the activity of AKP in mucus and head kidney on any time points (P>0.05), and the activity of AKP in liver was significantly increased on day 3 and 4 (P<0.05 or P<0.01); no significant difference was found in the activity of SOD in liver and head kidney on any time points (P>0.05), while the activity of SOD in mucus was significantly increased on any time points (P<0.05 or P<0.01); the activity of LSZ in mucus and liver was significantly increased on day 1 (P<0.05 or P<0.01) and then got the peak on day 2, while the activity of LSZ in head kidney was firstly increased and then decreased and only got a significant increase on day 5 (P<0.05). N. seriolae challenge experiment result showed that protective rate for C. argus after the WPG intraperitoneal injection on day 7, 21 and 35 were 35%, 55% and 60%, respectively. The above results indicate that WPG from N. seriolae has a significantly regulating effect on haemocytes PI, serum ACH50, and tissue ACP, AKP, SOD and LSZ activities of C. argus, but the strength of regulating effect is different in different tissues. There is a significant protective effect for Nocardia infected C. argus with the WPG from N. seriolae intraperitoneal injection more than 21 days.