Fisheries Science

, Volume 77, Issue 4, pp 623–632

Identification and molecular typing of Streptococcus agalactiae isolated from pond-cultured tilapia in China

  • Xing Ye
  • Jiong Li
  • Maixin Lu
  • Guocheng Deng
  • Xiaoyan Jiang
  • Yuanyuan Tian
  • Yingchun Quan
  • Qian Jian
Original Article Aquaculture

DOI: 10.1007/s12562-011-0365-4

Cite this article as:
Ye, X., Li, J., Lu, M. et al. Fish Sci (2011) 77: 623. doi:10.1007/s12562-011-0365-4

Abstract

Bacteria strains with strong virulence were isolated from pond-cultured tilapia in China. They were identified as Streptococcus agalactiae by biochemical assays, and confirmed by 16S ribosomal RNA (rRNA) and group B Streptococcus (GBS)-specific gene cfb analyses. Multiplex polymerase chain reaction (PCR) assay of the alpha C protein (ACP) gene and capsular polysaccharide antigen (cps) gene was employed to identify their molecular serotype (MS). Amplification of the ACP gene produced a 400-bp C alpha protein gene (bca) fragment, suggesting that these isolates belong to MS Ia, Ib or II; amplification of cps produced a 790-bp amplicon, indicating that they belong to MS Ia/III-3. An additional PCR based on nucleotide difference in the cps H–I region of MS Ia and III further suggested that the isolates belong to serotype MS Ia. Moreover, multi-locus sequence typing (MLST) indicated that these strains were of sequence type 7 (ST-7). These results showed that isolates from different regions of China shared the same MS and ST. However, none of the isolated ST-7 GBS corresponded to the capsular serotype, suggesting that these fish GBS possessed specific molecular characteristics not present in human or other animals. Data from this study will facilitate the understanding of epidemiology and nosogenesis of tilapia GBS and the establishment of effective disease prevention methods.

Keywords

Tilapia Streptococcus agalactiae Molecular serotype ACP cps MS la MLST ST-7 

Copyright information

© The Japanese Society of Fisheries Science 2011

Authors and Affiliations

  • Xing Ye
    • 1
  • Jiong Li
    • 1
    • 2
  • Maixin Lu
    • 1
  • Guocheng Deng
    • 1
  • Xiaoyan Jiang
    • 1
  • Yuanyuan Tian
    • 1
  • Yingchun Quan
    • 1
  • Qian Jian
    • 1
  1. 1.Pearl River Fishery Research InstituteCAFSGuangzhouChina
  2. 2.College of Fisheries and LifeShanghai Ocean UniversityShanghaiChina

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