10种CpG-ODNs对罗非鱼抗海豚链球菌感染的作用

采用人工合成的10种未甲基化CpG-ODNs序列分别注射健康的吉富罗非鱼Oreochromis niloticus,48 h后注射海豚链球菌(Streptococcus iniae)进行人工感染,分别于感染24 h和48 h后检测鱼体血清溶菌酶(Lysozyme,LSZ)、超氧化物歧化酶(Superoxide dismutase,SOD)和碱性磷酸酶(Alkaline phosphatase,AKP)的活性,并记录死亡率。结果显示:注射ODN-205的罗非鱼LSZ、AKP和SOD活性变化均不显著(P>0.05),推测注射ODN-205后罗非鱼能较好的维持机体的平衡,增强机体的抗菌能力;注射ODN-1681、1670、2133和2006的罗非鱼LSZ活性逐渐降低,而注射ODN-1826、2143、1668、2102、1669的罗非鱼LSZ活性呈现先升高后降低的趋势。AKP活性的变化趋势同LSZ活性变化大体相似,而SOD活性前后变化不显著(p值>0.05)。注射CpG-ODNs的实验组抑制海豚链球菌感染的作用差异显著(p值<0.05),其中以注射ODN-205组的死亡率最低(18%),其次为注射ODN-1670、1681、2006和2133组,死亡率均低于30%,而ODN-1669组和生理盐水组的死亡率均超过90%。实验表明,注射一定量的ODN-205、1670、1681、2006和2133能明显提高吉富罗非鱼抗海豚链球菌感染能力。

Effects of Injecting 10 Kinds of CpG ODNs on the Resistance of Tilapia （Oreochromis niloticus） against Streptococcus iniae

Tilapia,Oreochromis niloticus were injected with 10 kinds of CpG-ODNs and then challenged by Streptococcus iniae after 48 h.The activities of lysozyme（LSZ）,superoxide dismutase（SOD） and alkaline phosphatase（AKP） of serum were measured respectively after being infected 24 h and 48 h later,then the mortality rates were calculated.The results showed that there was no significant difference between ODN-205 and control groups for LSZ、SOD and AKP activities at 24 h and 48 h（p0.05）.The activities of LSZ and AKP of the groups（ODN-1670,1681,1826 and 2006） decreased slowly at 48h after injection while the activities of LSZ and AKP of the groups（ODN-1826,2143,1668,2102,1669） increased first and then decreased at 48h.There was no significant difference among treaments and control groups for SOD activity at 24 h and 48 h（p0.05）.For anti-infection of S.iniae,significant differences were found among all the treat ments（p0.05）,and the mortality rate of ODN-205 group was the lowest（18%）.In groups of ODN-1670、1681、2006 and 2133,the mortality rates were all less than 30%,while in ODN-1669 and control groups,the mortality rates were the highest（93%）.Therefore,the present study indicated that ODN-205,1670,1681,2006 and 2133 could improve the resistance of potential S.iniae infection.