title: Characterization of a mucoid clone of Streptococcus zooepidemicus from an epizootic of equine respiratory disease in New Caledonia.
abstract: Streptococcus equi subspecies zooepidemicus (Sz) is a tonsillar and mucosal commensal of healthy horses with the potential to cause opportunistic infections of the distal respiratory tract stressed by virus infection, transportation, training or high temperature. The invasive clone varies from horse to horse with little evidence of lateral transmission in the group. Tonsillar isolates are non-mucoid although primary isolates from opportunist lower respiratory tract infections may initially be mucoid. In this study, a novel stably mucoid Sz (SzNC) from a clonal epizootic of respiratory disease in horses in different parts of New Caledonia is described. SzNC (ST-307) was isolated in pure culture from transtracheal aspirates and as heavy growths from 80% of nasal swabs (n=31). Only 4% of swabs from unaffected horses (n=25) yielded colonies of Sz. A viral etiology was ruled out based on culture and early/late serum antibody screening. Evidence for clonality of SzNC included a mucoid colony phenotype, SzP and SzM sequences, and multilocus sequence typing. SzNC, with the exception of isolates at the end of the outbreak, was hyaluronidase positive. Its SzP protein was composed of an N2 terminal, and HV4 variable region motifs and 18 carboxy terminal PEPK repeats. Biotin labeling of surface proteins revealed DnaK and alanyl-tRNA synthetase (AlaS) on the surface of clonal isolates, but not on non-clonal non-mucoid Sz from horses in the epizootic or unrelated US isolates. Reactivity of these proteins and SzP with convalescent serum indicated expression during infection.
authors.affiliation: Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA.
authors.forename: Sridhar
authors.initials: S
authors.lastname: Velineni
authors.affiliation: Laboratoire Territorial de Diagnostic Vétérinaire, BP42 Paita, New Caledonia.
authors.forename: Denise
authors.initials: D
authors.lastname: Desoutter
authors.affiliation: Laboratoire Territorial de Diagnostic Vétérinaire, BP42 Paita, New Caledonia.
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Perchec
authors.affiliation: Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA. Electronic address: jtimoney@uky.edu.
authors.forename: John F
authors.initials: JF
authors.lastname: Timoney
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D006734:Horse Diseases / Q000382:microbiology*; D006736:Horses; D008969:Molecular Sequence Data; D058885:Multilocus Sequence Typing / Q000662:veterinary; D009510:New Caledonia; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012141:Respiratory Tract Infections / Q000382:microbiology / Q000662:veterinary*; D017422:Sequence Analysis, DNA / Q000662:veterinary; D013290:Streptococcal Infections / Q000382:microbiology / Q000662:veterinary*; D018502:Streptococcus equi / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C107892:SzPSe protein, Streptococcus equi
keywords: AlaS; Clonal outbreak; DnaK; Mucoid SzNC; ST-307