Analysis of serotypes, spaA gene phylogeny and PFGE genetic patterns of Erysipelothrix rhusiopathiae isolated between 2012 and 2015 in Jianghuai areas

Abstract:

[Objective] To study the serotypes, phylogeny of surface protective antigen A gene (spaA), and molecular subtyping of Erysipelothrix rhusiopathiae isolated between 2012 and 2015 in Jianghuai area. [Methods] We collected 42 clinically isolated Erysipelothrix rhusiopathiae strains. Agar gel precipitation tests, PCR and sequence analysis methods, and pulsed-field gel electrophoresis were used to investigate the serotypes, phylogeny of spaA gene, and PFGE typing, respectively. [Results] All 42 strains belonged to serotype 1a. spaA gene was 98.5% to 100% homologous to the reference strains. The sequences showed that the mutations occurred from T to G and C to A at base 609th and 769th respectively, and the corresponding amino acid showed mutations from Ile to Met as Met-203-type, and Leu to Ile as Ile-257-type strains; PFGE revealed 8 different genotypes, with 88.8% to 100% similarity. ER2 (54.8%) was the dominant PFGE genotype, and erysipelas attenuated vaccine strains (G4T10 and GC42) were the same genotype strains. [Conclusion] Erysipelothrix rhusiopathiae serotype 1a was the prevalent serotypes in Jianghuai area. The homology of the spaA was high and had small variations. All the isolates came from one clone strain. Met-203-type and Ile-257-type strains had high pathogenicity and were the most prevalent pathogens type in Jianghuai area.

Key words:Erysipelothrix rhusiopathiae, Serotypes, Surface protective antigen A gene, Pulsed-field gel electrophoresis