Abstract
BackgroundGlaesserella parasuis (G. parasuis) is a respiratory pathogen of swine and the etiological agent of Glässer’s disease. The structural organization of genetic information, antibiotic resistance genes, potential pathogenicity, and evolutionary relationships among global G. parasuis strains remain unclear. The aim of this study was to better understand patterns of genetic variation, antibiotic resistance factors, and virulence mechanisms of this pathogen.MethodsThe whole-genome sequence of a ST328 isolate from diseased swine in China was determined using Pacbio RS II and Illumina MiSeq platforms and compared with 54 isolates from China sequenced in this study and 39 strains from China and eigtht other countries sequenced by previously. Patterns of genetic variation, antibiotic resistance, and virulence mechanisms were investigated in relation to the phylogeny of the isolates. Electrotransformation experiments were performed to confirm the ability of pYL1—a plasmid observed in ST328—to confer antibiotic resistance.ResultsThe ST328 genome contained a novel Tn6678 transposon harbouring a unique resistance determinant. It also contained a small broad-host-range plasmid pYL1 carrying aac(6’)-Ie-aph(2”)-Ia and blaROB-1; when transferred to Staphylococcus aureus RN4220 by electroporation, this plasmid was highly stable under kanamycin selection. Most (85.13–91.74%) of the genetic variation between G. parasuis isolates was observed in the accessory genomes. Phylogenetic analysis revealed two major subgroups distinguished by country of origin, serotype, and multilocus sequence type (MLST). Novel virulence factors (gigP, malQ, and gmhA) and drug resistance genes (norA, bacA, ksgA, and bcr) in G. parasuis were identified. Resistance determinants (sul2, aph(3”)-Ib, norA, bacA, ksgA, and bcr) were widespread across isolates, regardless of serovar, isolation source, or geographical location.ConclusionsOur comparative genomic analysis of worldwide G. parasuis isolates provides valuable insight into the emergence and transmission of G. parasuis in the swine industry. The result suggests the importance of transposon-related and/or plasmid-related gene variations in the evolution of G. parasuis.
Highlights
Glaesserella parasuis, a gram-negative bacterium in the family Pasteurellaceae (Dickerman, Bandara & Inzana, 2020), is a respiratory pathogen that affects swine
As China is one of the world’s largest pork producers, with more than 463 million pigs accounting for approximately 50% of global population (Zhou et al, 2013), G. parasuis outbreaks in this country could pose a significant threat to pig health and economic loss worldwide (Brockmeier et al, 2014)
Compilation of the 94 genomes covering all serovars and disease- and non-disease-causing backgrounds from nine geographic locations (Table S4) demonstrated expansion of the pan-genome, whereas the number of core genes remained relatively stable with the addition of new strains (Fig. 1A)
Summary
Glaesserella parasuis, a gram-negative bacterium in the family Pasteurellaceae (Dickerman, Bandara & Inzana, 2020), is a respiratory pathogen that affects swine. It is the etiological agent of Glässer’s disease, which can lead to pneumonia without signs of systemic disease (Brockmeier, 2004). Disease progression and severity are influenced by virulence and antibiotic resistance, both of which can result from evolutionary processes including mutation and horizontal gene transfer (Deng et al, 2019). The aim of this study was to better understand patterns of genetic variation, antibiotic resistance factors, and virulence mechanisms of this pathogen. Novel virulence factors (gigP, malQ, and gmhA) and drug resistance genes (norA, bacA, ksgA, and bcr) in G. parasuis were identified. The result suggests the importance of transposon-related and/or plasmid-related gene variations in the evolution of G. parasuis
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.
