Mugabi, Robert;
Silva, Ana Paula S. Poeta;
Hu, Xiao;
Gottschalk, Marcelo;
Aragon, Virginia;
Macedo, Nubia R.;
Sahin, Orhan;
Harms, Perry;
Main, Rodger;
Tucker, Alexander W.;
Li, Ganwu;
Clavijo, Maria J.
Molecular characterization of Glaesserella parasuis strains circulating in North American swine production systems
Beschreibung:
<jats:title>Abstract</jats:title><jats:sec>
<jats:title>Background</jats:title>
<jats:p><jats:italic>Glaesserella parasuis</jats:italic> is the causative agent of Glässer’s disease in pigs. Serotyping is the most common method used to type <jats:italic>G. parasuis</jats:italic> isolates. However, the high number of non-typables (NT) and low discriminatory power make serotyping problematic. In this study, 218 field clinical isolates and 15 <jats:italic>G. parasuis</jats:italic> reference strains were whole-genome sequenced (WGS). Multilocus sequence types (MLST), serotypes, core-genome phylogeny, antimicrobial resistance (AMR) genes, and putative virulence gene information was extracted.</jats:p>
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<jats:title>Results</jats:title>
<jats:p>In silico WGS serotyping identified 11 of 15 serotypes. The most frequently detected serotypes were 7, 13, 4, and 2. MLST identified 72 sequence types (STs), of which 66 were novel. The most predominant ST was ST454. Core-genome phylogeny depicted 3 primary lineages (LI, LII, and LIII), with LIIIA sublineage isolates lacking all vtaA genes, based on the structure of the phylogenetic tree and the number of virulence genes. At least one group 1 <jats:italic>vtaA</jats:italic> virulence genes were observed in most isolates (97.2%), except for serotype 8 (ST299 and ST406), 15 (ST408 and ST552) and NT (ST448). A few group 1 <jats:italic>vtaA</jats:italic> genes were significantly associated with certain serotypes or STs. The putative virulence gene <jats:italic>lsgB</jats:italic>, was detected in 8.3% of the isolates which were predominantly of serotype 5/12. While most isolates carried the <jats:italic>bcr</jats:italic>, <jats:italic>ksgA</jats:italic>, and <jats:italic>bacA</jats:italic> genes, the following antimicrobial resistant genes were detected in lower frequency; <jats:italic>blaZ</jats:italic> (6.9%), <jats:italic>tetM</jats:italic> (3.7%), <jats:italic>spc</jats:italic> (3.7%), <jats:italic>tetB</jats:italic> (2.8%), <jats:italic>bla-ROB-1</jats:italic> (1.8%), <jats:italic>ermA</jats:italic> (1.8%), <jats:italic>strA</jats:italic> (1.4%), <jats:italic>qnrB</jats:italic> (0.5%), and <jats:italic>aph3''Ia</jats:italic> (0.5%). </jats:p>
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<jats:title>Conclusion</jats:title>
<jats:p>This study showed the use of WGS to type <jats:italic>G. parasuis</jats:italic> isolates and can be considered an alternative to the more labor-intensive and traditional serotyping and standard MLST. Core-genome phylogeny provided the best strain discrimination. These findings will lead to a better understanding of the molecular epidemiology and virulence in <jats:italic>G. parasuis</jats:italic> that can be applied to the future development of diagnostic tools, autogenous vaccines, evaluation of antibiotic use, prevention, and disease control.</jats:p>
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