三黄连合剂对罗非鱼人工感染海豚链球菌病的预防效果

Preventive effect of Chinese herbal compound“Sanhuanglian”on tilapia infected artificially with Dolphin Streptococcus

【目的】探讨三黄连合剂对由海豚链球菌感染罗非鱼发病的预防效果,为罗非鱼链球菌病的免疫防治提供参考依据。【方法】分别以含30、60、120 m L/kg三黄连合剂的饵料投喂吉富罗非鱼,连续投喂7 d,给药后第8 d进行人工感染海豚链球菌,感染后第7 d测定脾脏指数,同时于感染后0、12、24 h和7 d采集血清样本,检测超氧化物歧化酶(SOD)、溶菌酶(LSZ)、碱性磷酸酶(AKP)、血清补体C3、Ig M抗体水平等免疫学指标。【结果】三黄连合剂连续给药7 d对吉富罗非鱼血清免疫指标均有一定影响,可显著提高吉富罗非鱼血清SOD活性(P<0.05,下同)。人工感染海豚链球菌后第7 d,3个三黄连合剂处理组的罗非鱼脾脏指数较感染不给药组明显升高;在免疫指标方面,高剂量组(120m L/kg)罗非鱼的血清SOD活性、AKP活性、LSZ活性、补体C3活性、Ig M抗体水平均显著或极显著(P<0.01)高于感染不给药组。【结论】三黄连合剂可减轻因海豚链球菌感染而造成的免疫抑制,保护机体免疫系统,提升免疫力,对罗非鱼感染海豚链球菌有良好的预防效果。

[Objective]The preventive effect of Chinese herbal compound ＂Sanhuanglian＂ on tilapia streptococcicosis was investigated to provide theoretical references for immunnologieal control of tilapia streptoeoccicosis. [Method]Three groups of tilapia were feeded with 30, 60 and 120 mL/kg ＂Sanhuanglian＂ for 7 days, respectively, Tilapia from different groups were infected artificially with Dolphin Streptococcus on the 8th day after administration. On the 7~ day after infec- tion,the spleen index was determined. Meawhile the serum samples were collected at 0 h, 12 h,24 h and 7 d after infec- tion, respectively. Then the immunological indexes were determined, including the superoxide dismutase （SOD）, lysozyme （LSZ）, alkaline phosphatase （AKP）, complement C3 and IgM antibody levels in serum. [Results]Feeding with Chinese herbal compound ＂Sanhuanglian＂ for 7 days had a positive impact on immunological indexes of tilapia as follows： the superoxide dismutase （SOD） activity in tilapia significantly increased（P〈0.05,the same below）. On the 7th day after infection with D. Streptococcus, the spleen index of tilapia feeded with Chinese herbal compound ＂Sanhuanglian＂ also significantly increased compared with that of tilapia infected without administration. As for the immunological indexes, the tilapia （high-dose group） feeded with the 120 mL ＂Sanhuanglian＂ compound significantly or extremely significantly （P〈 0.01 ） increased in SOD activity, AKP activity, complement C3 and IgM antibody levels compared with that of tilapia in- fected without administration. [ Conclusion ] Chinese herbal compound ＂Sanhuanglian＂ can alleviate immunosuppression caused by D. streptococcal, protect immune systems, and enhance immunity, which have a good preventive effect of tilapia streptococeicosis.