Abstract
The availability of whole genome sequences in public databases permits genome-wide comparative studies of various bacterial species. Whole genome sequence-single nucleotide polymorphisms (WGS-SNP) analysis has been used in recent studies and allows the discrimination of various Brucella species and strains. In the present study, 13 Brucella spp. strains from cattle of various locations in provinces of South Africa were typed and discriminated. WGS-SNP analysis indicated a maximum pairwise distance ranging from 4 to 77 single nucleotide polymorphisms (SNPs) between the South African Brucella abortus virulent field strains. Moreover, it was shown that the South African B. abortus strains grouped closely to B. abortus strains from Mozambique and Zimbabwe, as well as other Eurasian countries, such as Portugal and India. WGS-SNP analysis of South African B. abortus strains demonstrated that the same genotype circulated in one farm (Farm 1), whereas another farm (Farm 2) in the same province had two different genotypes. This indicated that brucellosis in South Africa spreads within the herd on some farms, whereas the introduction of infected animals is the mode of transmission on other farms. Three B. abortus vaccine S19 strains isolated from tissue and aborted material were identical, even though they originated from different herds and regions of South Africa. This might be due to the incorrect vaccination of animals older than the recommended age of 4–8 months or might be a problem associated with vaccine production.
Highlights
The genus Brucella is a highly monomorphic genus comprised of gram-negative pathogenic species [1] affecting a wide range of hosts, including humans
Whole genome sequence-single nucleotide polymorphisms (WGS-SNP) analysis was used in the present study, based on previous reports demonstrating its efficacy in the discrimination of various conserved Brucella strains and biovars [25,26,27]
All of the isolates were biotyped at the Agricultural Research Council-Onderstepoort Veterinary Research (ARC-OVR), with most identified as B. abortus bv. 1, two as B. abortus bv.2, and two as B. abortus S19, as shown on Table 2 and previously in Ledwaba et al [35]
Summary
The genus Brucella is a highly monomorphic genus comprised of gram-negative pathogenic species [1] affecting a wide range of hosts, including humans. This document emphasizes that “to date, there are limited recent empirical data or published reports on the existence or prevalence of brucellosis in the livestock industry in South Africa”. It indicates that farmers buying replacement stock may be at risk of introducing infected animals to their herd since most farmers are not complying with the bovine brucellosis regulations. Whole genome sequence-single nucleotide polymorphisms (WGS-SNP) analysis was used in the present study, based on previous reports demonstrating its efficacy in the discrimination of various conserved Brucella strains and biovars [25,26,27]. Strains from ARC-OVR are grouped under the name “other” in the generated trees since they are isolated from samples submitted at the national reference laboratory from different regions throughout SA
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
