title: Molecular characterisation of 'strangles' outbreaks in the UK: the use of M-protein typing of Streptococcus equi ssp. equi.
abstract: BACKGROUND
  Strangles is the most commonly diagnosed and important infectious disease of horses worldwide. Very little is known about the temporo-spatial and molecular epidemiology of strangles. The disease is not notifiable in the UK and there are few published data on the geographical locations of outbreaks.
  
  
  OBJECTIVE
  To investigate whether typing of a surface protein (SeM) of Streptococcus equi ssp. equi (S. equi), the causative agent of strangles, is a useful epidemiological tool.
  
  
  METHODS
  The variable region of the SeM gene was amplified from 145 isolates of S. equi by PCR and sequenced. Different SeM gene alleles were assigned based on the SeM database, grouped into phylogenetic clusters using split decomposition analysis and plotted against the submitting veterinary practices.
  
  
  RESULTS
  In this study 21 S. equi SeM alleles were found, including 9 previously unidentified alleles and representing 4 phylogenetic groups. S. equi containing SeM alleles 9 and 7 were the most commonly isolated and there was a high number of low frequency alleles. The occurrence of an outbreak cluster in the north-west of the UK is also reported.
  
  
  CONCLUSIONS
  Strangles outbreaks can be differentiated on the basis of their SeM allele sequences. The data provide further evidence of SeM mutation leading to the emergence of novel, but related SeM alleles that are geographically linked. Sequencing of the SeM gene is a useful tool for the elucidation of strangles epidemiology at a regional and a national level.
  
  
  CONCLUSIONS
  This technique may allow differentiation or linkage of strangles outbreaks and as such may be an effective tool for local as well as national and international disease surveillance.
authors.affiliation: Equine Referral Hospital, The Royal Veterinary College, UK. philip@nixonequinevets.co.uk
authors.forename: P A S
authors.initials: PA
authors.lastname: Ivens
authors.forename: D
authors.initials: D
authors.lastname: Matthews
authors.forename: K
authors.initials: K
authors.lastname: Webb
authors.forename: J R
authors.initials: JR
authors.lastname: Newton
authors.forename: K
authors.initials: K
authors.lastname: Steward
authors.forename: A S
authors.initials: AS
authors.lastname: Waller
authors.forename: C
authors.initials: C
authors.lastname: Robinson
authors.forename: J D
authors.initials: JD
authors.lastname: Slater
mesh_terms: D000483:Alleles; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004196:Disease Outbreaks / Q000662:veterinary*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D006734:Horse Diseases / Q000453:epidemiology / Q000382:microbiology*; D006736:Horses; D010802:Phylogeny; D013290:Streptococcal Infections / Q000382:microbiology / Q000662:veterinary*; D018502:Streptococcus equi / Q000235:genetics*; D006113:United Kingdom / Q000453:epidemiology
chemical_list: D001426:Bacterial Proteins