title: Gene content and diversity of the loci encoding biosynthesis of capsular polysaccharides of the 15 serovar reference strains of Haemophilus parasuis.
abstract: Haemophilus parasuis is the causative agent of Glässer's disease, a systemic disease of pigs, and is also associated with pneumonia. H. parasuis can be classified into 15 different serovars. Here we report, from the 15 serotyping reference strains, the DNA sequences of the loci containing genes for the biosynthesis of the group 1 capsular polysaccharides, which are potential virulence factors of this bacterium. We contend that these loci contain genes for polysaccharide capsule structures, and not a lipopolysaccharide O antigen, supported by the fact that they contain genes such as wza, wzb, and wzc, which are associated with the export of polysaccharide capsules in the current capsule classification system. A conserved region at the 3' end of the locus, containing the wza, ptp, wzs, and iscR genes, is consistent with the characteristic export region 1 of the model group 1 capsule locus. A potential serovar-specific region (region 2) has been found by comparing the predicted coding sequences (CDSs) in all 15 loci for synteny and homology. The region is unique to each reference strain with the exception of those in serovars 5 and 12, which are identical in terms of gene content. The identification and characterization of this locus among the 15 serovars is the first step in understanding the genetic, molecular, and structural bases of serovar specificity in this poorly studied but important pathogen and opens up the possibility of developing an improved molecular serotyping system, which would greatly assist diagnosis and control of Glässer's disease.
authors.affiliation: Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom. kjh52@cam.ac.uk
authors.forename: Kate J
authors.initials: KJ
authors.lastname: Howell
authors.forename: Lucy A
authors.initials: LA
authors.lastname: Weinert
authors.forename: Shi-Lu
authors.initials: SL
authors.lastname: Luan
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Peters
authors.forename: Roy R
authors.initials: RR
authors.lastname: Chaudhuri
authors.forename: David
authors.initials: D
authors.lastname: Harris
authors.forename: Oystein
authors.initials: O
authors.lastname: Angen
authors.forename: Virginia
authors.initials: V
authors.lastname: Aragon
authors.forename: Julian
authors.initials: J
authors.lastname: Parkhill
authors.forename: Paul R
authors.initials: PR
authors.lastname: Langford
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Rycroft
authors.forename: Brendan W
authors.initials: BW
authors.lastname: Wren
authors.forename: Alexander W
authors.initials: AW
authors.lastname: Tucker
authors.forename: Duncan J
authors.initials: DJ
authors.lastname: Maskell
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015373:Bacterial Typing Techniques; D014644:Genetic Variation; D006192:Haemophilus Infections / Q000382:microbiology / Q000662:veterinary; D044137:Haemophilus parasuis / Q000145:classification* / Q000235:genetics* / Q000378:metabolism; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D017422:Sequence Analysis, DNA; D012703:Serotyping; D013045:Species Specificity; D034421:Sus scrofa; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*; D014774:Virulence; D037521:Virulence Factors / Q000096:biosynthesis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D011135:Polysaccharides, Bacterial; D037521:Virulence Factors