中国水产科学研究院 珠江水产研究所, 农业部渔用药物创制重点实验室, 广东省水产动物免疫技术重点实验室, 广东 广州 510380
作者简介: 张德锋(1985–), 男, 博士, 助理研究员, 主要从事水产病害与免疫研究. E-mail: zhangdefeng08@126.com 通信作者: 吴淑勤(1956–), 研究员. E-mail: gzwushuqin@163.com
S941, Q938.8
国家科技支撑计划项目(2012BAD25B02); 现代农业产业技术体系建设专项资金项目(CARS-46).
Pearl River Fishery Research Institute, Chinese Academy of Fishery Sciences; Key Laboratory of Fishery Drug Development, Ministry of Agriculture; Key Laboratory of Aquatic Animal Immune Technology, Guangzhou 510380, China
患病罗非鱼表现出体色发黑、打转游动、眼球突出或混浊等典型的链球菌病症状。从患病罗非鱼的肝、肾、脾、眼球和脑等组织中分离到即、WT1451~WT1459基因序列分析等方法对病原菌进行鉴定这些病原菌均为无乳链球菌。溶血试验结果表明β菌株为不溶血无乳链球菌。进一步通过、BL1441~BL1448 bcabibAcfbhylBiagAfbsBlmbgbs20186菌株则是+++++
occurred in Wenchang,Hainan Province, China in 2014. In this study, the moribund tilapias were collected from different farms for bacteriaisolation. Most of the moribund tilapias displayed typical clinical signs, such as melanosis, corneal opacity,and swimming abnormalities. A total of 19 isolates (TC-1, TC-2, BL1441 WT1459) wereisolated from the liver, kidney, spleen, eye, and brain of the diseased tilapia; then, these isolates were identified bymorphological observation, physiological, and biochemical characteristics, and sequence analysis of the 16S rRNAgene. All of the isolates were identified as –WT1459 strains grew slowly and couldnot utilize trehalose and ribose. In addition, TC-1, TC-2, and BL1441–’WT1459 isolates did not exhibit hemolysis. The geneticcharacteristics of these isolates were analyzed by multilocus sequence typing (MLST), molecular serotyping, andvirulence-related gene sequencing. The results indicated that TC-1, TC-2, and BL1441–S. agalactiae WT1459 isolates were rare typesof Ib-ST261 BL1448 isolates, and the virulence-relatedgenotype of these strains was +. Despite the fact that thenumber of the virulence-related genes of the WT1451 strain was less than that of the BL1441 strain, the formerwas more virulent than the latter in tilapia. In this study, the virulence tests were conducted by intraperitoneal injectionof the BL1441 and WT1451 strains in tilapia. The results of the challenge experiments showed that theWT1451 strain possessed stronger pathogenicity to tilapia than that of BL1441 strain. The WT1451 strain caused85% mortality in tilapia at a dose of 4.5CFU/mL. The BL1441 strain showed weak virulence in tilapia, withcumulative mortality of 65% at a dose of 4.5CFU/mL postchallenge. In summary, the 19 strainsisolated from tilapia in Wenchang were divided into two genotypes based on physiological and biochemical characteristics,16S rRNA gene sequences, hemolysis activity, molecular serotyping, and PCR screening of virulence-related genes. Although reports on the Ib-ST261 strains in tilapia are rare worldwide, thesestrains were highly virulent in tilapia. Therefore, it is very important to obtain data on the epidemiology ofIb-ST261 strains in tilapia in China. To the best of our knowledge, this is the first report on the hypervirulentIb-ST261 strain of , which was isolated from tilapia in China. This study provides aframework for the exploration of epidemiological analysis, vaccine development, prevention, and treatment of
张德锋,刘礼辉,任燕,李宁求,林强,潘厚军,石存斌,吴淑勤.我国罗非鱼源新型无乳链球菌的分离、鉴定及其分子特征[J].中国水产科学,2015,22(5):1044-1054
ZHANG Defeng, LIU Lihui, REN Yan, LI Ningqiu, LIN Qiang, PAN Houjun, SHI Cunbin, WU Shuqin. Isolation, identification, and molecular characteristics of a new genotypeof Streptococcus agalactiae from cultured tilapia in China[J]. Journal of Fishery Sciences of China,2015,22(5):1044-1054
