Ovine Mannheimia haemolytica isolates from lungs with and without pneumonic lesions belong to similar genotypes

•Sheep isolates from lungs without and with pneumonic lesions were characterized.•Most isolates from lungs with and without pneumonic lesions belonged to the same STs.•MLST data suggest adaptation of certain genetic lineages to small ruminants.•Isolates from lungs with and without lesions exhibited...

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Bibliographic Details
Published in:Veterinary microbiology 2018-06, Vol.219, p.80-86
Main Authors: García-Alvarez, Andrés, Fernández-Garayzábal, José Francisco, Chaves, Fernando, Pinto, Chris, Cid, Dolores
Format: Article
Language:English
Subjects:
Animal diseases
Electrophoresis
Gel electrophoresis
Genetic analysis
Genetic diversity
Genotype & phenotype
Genotypes
Lesions
Lungs
Mannheimia haemolytica
MLST
Molecular characterization
Multilocus sequence typing
PFGE
Pneumonia
Population structure
Pulsed-field gel electrophoresis
Sheep
Veterinary medicine
Virulence
Virulence genes
Virulotyping
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Summary:•Sheep isolates from lungs without and with pneumonic lesions were characterized.•Most isolates from lungs with and without pneumonic lesions belonged to the same STs.•MLST data suggest adaptation of certain genetic lineages to small ruminants.•Isolates from lungs with and without lesions exhibited similar genetic background.•Multiple strains of M. haemolytica cause individual cases of pneumonia in sheep. This study investigated the genetic characteristics of 121 ovine Mannheimia haemolytica isolates from lungs with (n = 75) and without pneumonic lesions (n = 46) using multilocus sequence typing (MLST), virulence-associated gene typing and pulsed-field gel electrophoresis (PFGE). Twelve STs were identified with most isolates (81%) belonged to ST16, ST28 and ST8. Analysis of the M. haemolytica MLST Database indicate a wide distribution of these genotypes in small ruminants, never reported in bovine isolates. This could suggest the adaptation of certain genetic lineages of M. haemolytica to small ruminants. e-BURST analysis grouped most STs into three clonal complexes (CC2, CC8 and CC28), consistent with a clonal population structure of M. haemolytica. Virulence-associated gene typing identified five virulence profiles in 64% and 65.1% of the M. haemolytica isolates from lungs with and without pneumonic lesions, respectively. These data suggest that M. haemolytica isolates from the lungs with and without pneumonic lesions are genetically homogeneous. By PGFE analysis a high level of genetic diversity was observed not only within isolates from lungs without pneumonic lesions but also among isolates from pneumonic lesions (GD 0.69 and GD 0.66, respectively; P > 0.05). These results indicate that multiple strains of M. haemolytica may be associated with individual cases of pneumonia in sheep.
ISSN:0378-1135
1873-2542
DOI:10.1016/j.vetmic.2018.04.012