2012–2015年江淮地区猪丹毒杆菌分离株血清型、spaA基因遗传进化及PFGE基因型分析

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

摘要:

【目的】了解2012–2015年江淮地区猪丹毒杆菌分离株血清型分布、spaA基因遗传进化关系和基因分型特征。【方法】收集临床分离鉴定的42株猪丹毒杆菌，应用琼脂扩散沉淀实验、PCR扩增和序列分析技术、脉冲场凝胶电泳分型技术(PFGE)分别测定分离株的血清型、spaA基因遗传变异性及PFGE基因型。【结果】42株猪丹毒杆菌分离株血清型均为1a型；spaA基因与猪丹毒杆菌国内外参考株核苷酸序列相似性为98.5%–100%，分离株在第609 bp处出现T突变为G、769 bp处C突变为A，对应的氨基酸第203位Ile突变为Met、第257位Leu突变为Ile，为Met-203、Ile-257型；分离株形成8个PFGE基因型，相似度达88.8%–100%，优势基因型为ER2 (54.8%)，弱毒疫苗G4T10和GC42株独立为同一个基因型。【结论】江淮地区致病猪丹毒杆菌流行血清型为1a型，spaA基因相似性高，分离株变异小、源于同一克隆系，Met-203、Ile-257型菌株致病力强，是江淮地区猪丹毒发生与流行的主要致病菌型。

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.