中国猪种布鲁氏菌分子流行病学特征分析

Molecular epidemiological characteristics of Brucella suis in China

摘要:

[目的] 调查猪种布鲁氏菌的基因多态性和分子流行病学特征。[方法] 用经典分型方法对菌株的生物型进行鉴定，分析菌株的地理分布特点；用MLVA-16分型方法对60株猪种布鲁氏菌进行基因分型，采用在线软件评估分型方法的分辨率和位点的多态性，用BioNumerics 5.0软件进行聚类分析。[结果] 我国流行的猪种布鲁氏菌主要是猪种生物1型（33株）、2型（3株）和3型菌（24株）；分布范围较广，包括广东、广西、内蒙古、北京、吉林、宁夏和西藏等地。MLVA-16分型方法对猪种布鲁氏菌具有极高的分辨力，多态性指数为0.992；Panel1、MLVA-11和Panel 2B均具有较高的分辨率，多态性指数分别为0.884、0.916和0.979。60株猪种布鲁氏菌聚为6大类52个基因型，5个共享基因型（GT24，GT25，GT26，GT28，GT29）包括13株布鲁氏菌，各基因型菌株间有潜在的流行病学关联，可能是分别来自相同传染源的暴发流行；另47株布鲁氏菌呈现独特的基因型，表明菌株来自无流行病学关联的零星散发病例。猪种布鲁氏菌的最小生成树表明我国菌株分别与美国、法国和波兰的菌株有完全相同的MLVA-15基因型。[结论] 中国猪种布鲁氏菌有较高的遗传多态性，并与美国、法国和阿根廷的菌株有较高的遗传相似性。我国猪种布病以零星散发为主。

Abstract:

[Objective] The aim of the present study was to investigate molecular epidemiology and genetic diversity characteristics of Brucella suis strains isolated from 14 different regions in China.[Methods] Biotypes of strains were discriminated by classical identification methods, both geographic distribution and etiology feature of B. suis were analyzed. Meanwhile, MLVA-16 genotyping assay was employed for genotyping of 60 B. suis strains. Diversity of each loci and resolution of genotyping assay were evaluated using online software.[Results] Our data indicated that three B. suis biovars (bv.1, 2, 3) were coexisted and strains numbers was 33, 2 and 24, respectively. Distribution of B. suis was wide and 14 provinces, Guangdong, Guangxi, Inner Mongolia, Beijing, Jilin, Ningxia, Xinjiang and Xizang were included. MLVA-16 approach is an excellent resolution for B. suis population, and diversity index of complete 16 loci was 0.992 based on Hunter-Gaston Discriminatory Index (HGDI). High resolution was observed in panel 1, MLVA-11 and panel 2b, their diversity index was 0.884, 0.916 and 0.979, respectively. Sixty B. suis strains were sorted into 6 clusters and formed 52 genotypes, 5 share (GT24,GT25, GT26, GT28 and GT29) genotypes including 13 isolates. The data indicated that these isolates have potential molecular epidemiology links, which maybe an outbreak from respective common source of infection. Remaining 47 genotypes being represented the single isolates, revealed that there also had unrelated and sporadic cases. A minimum spanning tree for B. suis using MLVA-15 revealed that China B. suis strains had complete identical MLVA-15 Genotypes with strains previously collected in America, France and Argentina.[Conclusion] B. suis strains of this study exhibited higher genetic diversity, as well as high genetic homology with strains obtained from America, France and Poland. The epidemic characterization of B. suis in China was sporadic.