Study of epidemiological and molecular characteristics of Brucella strains circulating in Kazakhstan

Brucellosis is one of the most common zoonotic infectious diseases of animals. The causative agent of brucellosis is a highly conserved bacterium of the genus Brucella, which includes 14 species with minor genetic changes. Our work aimed to study the epidemiological and molecular characteristics of Brucella strains circulating in Kazakhstan, including the study of polymorphisms in critical virulence genes using single nucleotide polymorphism (SNP) analysis based on whole genome sequencing (WGS). A total of 21 Brucella isolates obtained in 2023-2024 from cattle, sheep and goats, horses, camels, pigs, dogs, and humans were analyzed. As a result of whole-genome sequencing, 69 virulence genes were detected. The genome of Brucella melitensis, the most virulent species of Brucella, was the most susceptible to changes. Among the 10 virulence genes studied using SNP, polymorphisms were found in 7 genes. Some genetic mutations resulted in amino acid changes in the coding sequences of these virulence genes. Knowledge of virulence factors and changes in their coding genes has practical implications for epidemiological studies in outbreak areas, their management, and the implementation of brucellosis control strategies.