Molecular epidemiological characteristics of Brucella suis in China

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.