Molecular characteristics of Brucella melitensis isolates from humans in Qinghai Province, China

Abstract Background The prevalence of human brucellosis in Qinghai Province China has been increasing rapidly, with confirmed cases distributed across 31 counties. However, the epidemiology transmission not fully elucidated. To characterize infecting strains isolated from humans, multiple-locus variable-number tandem repeats analysis (MLVA) and whole-genome single-nucleotide polymorphism (SNP)-based approaches were employed. Methods Strains two males blood cultures that Brucella melitensis positive following biotyping MLVA. Genomic DNA was extracted these strains, sequencing performed. Next, SNP-based phylogenetic performed to compare 94 B. (complete genome draft genome) retrieved online databases. Results isolates identified as biovar 3 (QH2019001 QH2019005) conventional found have differences their variable number (VNTRs) using MLVA-16. Phylogenetic examination assigned 96 five genotype groups, QH2019001 QH2019005 same group, but different subgroups. Moreover, strain a new subgenotype, IIj, within II. These findings then combined determine geographic origin strains. Conclusions Utilizing approach enabled between be more clearly resolved, facilitated elucidation evolutionary histories. This also revealed is member subgenotype (IIj) an ancient eastern Mediterranean Sea.