Genome Sequences of Brucella Melitensis Strains QH2019001 and QH2019005 Provides Insight Into Different Evolutionary Origins Within Qinghai Province, China

Abstract

<jats:title>Abstract</jats:title> <jats:p>Background Brucellosis, which is cause by <jats:italic>Brucella</jats:italic>, is one of the most important zoonoses and is considered a “forgotten, neglected zoonosis” by the WHO. Methods Blood samples were isolated from two brucellosis males that were confirmed <jats:italic>B. melitensis</jats:italic> positive following multiple loci variable-number tandem repeat analysis (MLVA) and strains QH2019001 and QH2019005 were identified. Genomic DNA was extracted from these samples and whole genome sequencing (WGS) was performed. Next, SNP-based phylogenetic analysis was performed to compare the two strains to 94 <jats:italic>B. melitensis</jats:italic> strains (complete genome and draft genome) retrieved from online databases. Results The QH2019001 and QH2019005 strains were found to have differences in their variable-number tandem repeats. Phylogenetic examination of the 96 strains assigned them to 5 genotype groups, with QH2019001 and QH2019005 assigned to the same group, but to different subgroups; with the QH2019005 strain assigned to a new subgenotype, IIj. These findings were then combined to determine strain origin. Conclusions Utilizing a whole genome SNP-based approach highlights the diversity between <jats:italic>B. melitensis</jats:italic> strains, and it can facilitate the elucidation of different evolutionary histories. This approach also revealed that the QH2019005 is part of a new subgenotype with an ancient origin in the eastern Mediterranean Sea.</jats:p>