A Novel Glaesserella sp. Isolated from Pigs with Severe Respiratory Infections Has a Mosaic Genome with Virulence Factors Putatively Acquired by Horizontal Transfer
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Published:2018-06
Issue:11
Volume:84
Page:
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ISSN:0099-2240
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Container-title:Applied and Environmental Microbiology
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language:en
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Short-container-title:Appl Environ Microbiol
Author:
Watt Anne E.1ORCID, Browning Glenn F.1ORCID, Legione Alistair R.1, Bushell Rhys N.2, Stent Andrew2, Cutler Ross S.2, Young Neil D.2, Marenda Marc S.2ORCID
Affiliation:
1. Asia-Pacific Centre for Animal Health, Department of Veterinary Biosciences, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Melbourne, Victoria, Australia 2. Department of Veterinary Biosciences, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia
Abstract
ABSTRACT
An unknown member of the family
Pasteurellaceae
was repeatedly isolated from 20- to 24-week-old pigs with severe pulmonary lesions reared on the same farm in Victoria, Australia. The etiological diagnosis of the disease was inconclusive. The complete genome sequence analysis of one strain, 15-184, revealed some phylogenic proximity to
Glaesserella
(
Haemophilus
)
parasuis
, the cause of Glasser's disease. However, the sequences of the 16S rRNA and housekeeping genes, as well as the average nucleotide identity scores, differed from those of all other known species in the family
Pasteurellaceae
. The protein content of 15-184 was composite, with 60% of coding sequences matching known
G. parasuis
products, while more than 20% had a closer relative in the genera
Actinobacillus
,
Mannheimia
,
Pasteurella
, and
Bibersteinia
. Several putative virulence genes absent from
G. parasuis
but present in other
Pasteurellaceae
were also found, including the
apxIII
RTX toxin gene from
Actinobacillus pleuropneumoniae
, ABC transporters from
Actinobacillus minor
, and iron transporters from various species. Three prophages and one integrative conjugative element were present in the isolate. Horizontal gene transfers might explain the mosaic genomic structure and atypical metabolic and virulence characteristics of 15-184. This organism has not been assigned a taxonomic position in the family, but this study underlines the need for a large-scale epidemiological and clinical characterization of this novel pathogen in swine populations, as a genomic analysis suggests it could have a severe impact on pig health.
IMPORTANCE
Several species of
Pasteurellaceae
cause a range of significant diseases in pigs. A novel member of this family was recently isolated from Australian pigs suffering from severe respiratory infections. Comparative whole-genome analyses suggest that this bacterium represents a new species, which possesses a number of virulence genes horizontally acquired from a diverse range of other
Pasteurellaceae
. While the possible contribution of other coinfecting noncultivable agents to the disease has not been ruled out in this study, the repertoire of virulence genes found in this organism may nevertheless explain some aspects of the associated pathology observed on the farm. The prevalence of this novel pathogen within pig populations is currently unknown. This finding is of particular importance for the pig industry, as this organism can have a serious impact on the health of these animals.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Reference90 articles.
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