Brucella abortus in Kazakhstan, population structure and comparison with worldwide genetic diversity

Abstract

Brucella abortus is the main causative agent of brucellosis in cattle, leading to severe economic consequences in agriculture and affecting public health. The zoonotic nature of the infection increases the need to control the spread and dynamics of outbreaks in animals with the incorporation of high resolution genotyping techniques. Based on such methods, B. abortus is currently divided into three clades, A, B, and C. The latter includes subclades C1 and C2. This study presents the results of whole-genome sequencing of 49 B. abortus strains isolated in Kazakhstan between 1947 and 2015 and of 36 B. abortus strains of various geographic origins isolated from 1940 to 2004. In silico Multiple Locus Sequence Typing (MLST) allowed to assign strains from Kazakhstan to subclades C1 and to a much lower extend C2. Whole-genome Single-Nucleotide Polymorphism (wgSNP) analysis of the 46 strains of subclade C1 with strains of worldwide origins showed clustering with strains from neighboring countries, mostly North Caucasia, Western Russia, but also Siberia, China, and Mongolia. One of the three Kazakhstan strains assigned to subclade C2 matched the B. abortus S19 vaccine strain used in cattle, the other two were genetically close to the 104 M vaccine strain. Bayesian phylodynamic analysis dated the introduction of B. abortus subclade C1 into Kazakhstan to the 19th and early 20th centuries. We discuss this observation in view of the history of population migrations from Russia to the Kazakhstan steppes.

Global phylogenomic diversity of Brucella abortus: spread of a dominant lineage

“…In contrast, the other subclade contains no reference strains but does include a large number of isolates predominantly from Asia, particularly countries with extensive sampling such as Kazakhstan, Russia, and China, and to a lesser extent countries such as Brazil, Italy, Mongolia, and Georgia. The diversity and geographic distributions of clade C have been previously described and molecular dating indicates the arrival of this subclade into Kazakhstan in the 19th or early 20th century ( Shevtsov et al, 2023 ). One unusual finding from Italy is that despite strains sharing a common host, water buffalo, Italian herds are infected with strains from both clades C and D, suggesting two separate introductions and two distinct lineages have remained despite control efforts ( Garofolo et al, 2013 , 2017 ).…”

“…The third major lineage, identified as clade C (corresponding to C2 of MLSA) ( Whatmore et al, 2016 ; Shevtsov et al, 2023 ), contained isolates of diverse origins but came almost entirely from Europe and Asia ( Figure 4 ). Relative to the diversity within the African clades, the B. abortus genomes from clade C exhibited minimal genetic diversity but were substantially more diverse than the relatively monomorphic clade D (see below).…”

“…Clade C originated roughly in 972 CE (range 766–1102 CE), spread primarily into the Middle East and then into the rest of Asia, with some movement into Europe as well. The spread into Asia may have occurred along the Silk Road, as has been proposed for B. melitensis ( Pisarenko et al, 2018 ), although Shevtsov et al (2023) suggest that movement into Kazakhstan might have been much more recent, in the past 100–200 years. Clade C is well distributed across Eurasia, from present day western Europe to China, but represents considerably lower amounts of genetic diversity compared to the African lineages.…”

Regional epidemiology of brucellosis infection in modern conditions of animal husbandry technology in Kazakhstan (by the degree of spread and incidence)

“…A. Shevtsov et al (2023) and A.А. Taipova et al (2023) determined that in modern microbial taxonomy, Brucella occupies its place in the domain Bacteria, belonging to the type Proteobacteria, class Alphaproteobacteria, order Rhizobiales, family Brucellaceae and genus Brucella.…”

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“…A. Shevtsov et al (2023) and A.А. Taipova et al (2023) determined that in modern microbial taxonomy, Brucella occupies its place in the domain Bacteria, belonging to the type Proteobacteria, class Alphaproteobacteria, order Rhizobiales, family Brucellaceae and genus Brucella.…”