title: Distribution of genes involved in sialic acid utilization in strains of Haemophilus parasuis.
abstract: Haemophilus parasuis is a porcine respiratory pathogen, well known as the aetiological agent of Glässer's disease. H. parasuis comprises strains of different virulence, but the virulence factors of this bacterium are not well defined. A neuraminidase activity has been previously detected in H. parasuis, but the role of sialylation in the virulence of this bacterium has not been studied. To explore the relationship between sialic acid (Neu5Ac) and virulence, we assessed the distribution of genes involved in sialic acid metabolism in 21 H. parasuis strains from different clinical origins (including nasal and systemic isolates). The neuraminidase gene nanH, together with CMP-Neu5Ac synthetase and sialyltransferase genes neuA, siaB and lsgB, were included in the study. Neuraminidase activity was found to be common in H. parasuis isolates, and the nanH gene from 12 isolates was expressed in Escherichia coli and further characterized. Sequence analysis showed that the NanH predicted protein contained the motifs characteristic of the catalytic site of sialidases. While an association between the presence of nanH and the different origins of the strains was not detected, the lsgB gene was predominantly present in the systemic isolates, and was not amplified from any of the nasal isolates tested. Analysis of the lipooligosaccharide (LOS) from reference strains Nagasaki (virulent, lsgB(+)) and SW114 (non-virulent, lsgB(-)) showed the presence of sialic acid in the LOS from the Nagasaki strain, supporting the role of sialylation in the virulence of this bacterial pathogen. Further studies are needed to clarify the role of sialic acid in the pathogenicity of H. parasuis.
authors.affiliation: Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
authors.forename: Verónica
authors.initials: V
authors.lastname: Martínez-Moliner
authors.affiliation: Departamento de Microbiología y Parasitología, Universidad de Navarra, Pamplona, Spain.
authors.forename: Pedro
authors.initials: P
authors.lastname: Soler-Llorens
authors.affiliation: Instituto de Agrobiotecnología UPNA-CSIC-Gobierno Navarra, Mutilva, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Moleres
authors.affiliation: Instituto de Agrobiotecnología UPNA-CSIC-Gobierno Navarra, Mutilva, Spain.
authors.forename: Junkal
authors.initials: J
authors.lastname: Garmendia
authors.affiliation: Institut de Recerca i Tecnologia Agroalimentàries (IRTA), Barcelona, Spain.|Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
authors.forename: Virginia
authors.initials: V
authors.lastname: Aragon
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006192:Haemophilus Infections / Q000382:microbiology / Q000662:veterinary*; D044137:Haemophilus parasuis / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D008969:Molecular Sequence Data; D019158:N-Acetylneuraminic Acid / Q000378:metabolism*; D009439:Neuraminidase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D009439:Neuraminidase; D019158:N-Acetylneuraminic Acid