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Genetic diversity and new genotyping scheme for fish pathogenic S treptococcus agalactiae
Author(s) -
Godoy D.T.,
CarvalhoCastro G.A.,
Leal C.A.G.,
Pereira U.P.,
Leite R.C.,
Figueiredo H.C.P.
Publication year - 2013
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/lam.12138
Subject(s) - multilocus sequence typing , biology , genotyping , streptococcus agalactiae , virulence , genetic diversity , serotype , genetics , genetic variation , typing , microbiology and biotechnology , genotype , gene , streptococcus , population , demography , sociology , bacteria
This study aimed to assess the genetic diversity of fish isolates of S treptococcus agalactiae by capsular serotyping, MLST and the pattern of selected virulence genes. Forty‐six isolates from N ile tilapia and A mazon catfish were screened by PCR for the twelve virulence genes. The molecular capsular type and sequence type ( ST ) were determined. Two capsular types ( I a and I b) and four STs (103, 260, 552 and 553) were identified. The ST ‐552 and ST ‐553 represent new allelic combinations. Variable results were found for the genes gbs2018‐6 , lmb , hyl B and cyl E . The combined evaluation of serotype, sequence type and pattern of the presence or absence of cyl E and hyl B allowed the classification of isolates into nine genetic profiles ( I – IX ). The proposed scheme showed higher discriminatory power and was able to detect evolutionary events missed by MLST analysis. This study provides new information about the genetic diversity of fish pathogenic S trep. agalactiae, and the proposed scheme was shown to be an improved approach to genotyping these strains. Significance and Impact of the Study This study showed that critical genetic events in S treptococcus agalactiae isolates pathogenic for fish have been missed by serotyping and multilocus sequence typing ( MLST ). A proposed genotyping scheme based on the evaluation of concatenated data from serotyping, MLST , and the presence/absence of virulence genes was created, and this was able to detect old and recent evolutionary events. It provided a better understanding of the genetic diversity of S trep. agalactiae populations from fish and will contribute to future studies of the molecular epidemiology, pathogenesis and evolutionary aspects of this pathogen.