Multiple locus variable-number tandem repeat analysis on Brucella isolated in Sichuan, 2015–2019

  Objective  To understand the genotype of Brucella isolated in Sichuan Province and provide scientific evidence for the prevention and control of brucellosis.

  Methods  A total of 33 Brucella isolates were genotyped by multiple locus variable-number tandem repeat analysis (MLVA)-16. MLVA-8 genotype was queried by online public database, and cluster analysis of MLVA-16 was performed with UPGMA using software Bio Numerics.

  Results  The Brucella isolates were divided into 29 MLVA-16 genotypes with genetic similarity ranging from 74.6% to 100.0%. There were three MLVA-8 genotypes, including 42, 43 and 83, all of which originated from the Eastern Mediterranean group, and type 42 was predominant. The Simpson's index of MLVA-8 was 0.356, while that of MLVA-16 was 0.991. MLVA-16 can be used for local outbreak investigation and sporadic case surveillance.

  Conclusion  Brucella melitensis was the main pathogen causing brucellosis in Sichuan, and type 42 (MLVA-8 genotype) was the predominant genotype, consistent with strains isolated in other areas in China, suggesting that there was a correlation in incidence of brucellosis between Sichuan and provinces in northern China. For the first time, Brucella strains isolated in Sichuan were classified by MLVA, and the database constructed by them would provide basic data support for the surveillance and molecular traceability of brucellosis.