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Detection of DNA restriction fragment polymorphisms in Streptococcus equi
  1. S. Takai, DVM, MS, PhD1,
  2. H. Yashiro, DVM1,
  3. C. Ishii, DVM1,
  4. S. Tsubaki, DVM, PhD1,
  5. T. Anzai, DVM, PhD2,
  6. R. Wada, DVM, PhD2 and
  7. J. F. Timoney, BSc, MVB,MRCVS, MS, PhD, DSc3
  1. 1 Department of Animal Hygiene, School of Veterinary Medicine and Animal Sciences, Kitasato University, Towada, Aomori 034-8628 Japan
  2. 2 Epizootic Research Station, Equine Research Institute, Japan Racing Association, Kokubunji, Tochigi 329-0412, Japan
  3. 3 Department of Veterinary Science, Gluck Equine Research Center, University of Kentucky, Lexington, Kentucky, USA


Large-restriction-fragment (LRF) polymorphisms in Streptococcus equi (S equi subspecies equi) were studied by pulsed-field gel electrophoresis. Five or six chromosomal fragments of between 194 and 915 kb were separated by digestion with the restriction endonuclease Nofl. All 20 isolates of S equi, including 12 from independent Japanese outbreaks, four from independent American outbreaks, two from a single Irish outbreak, us vaccine strain F43, and type strain NCTC 9682 were successfully typed. Seven distinctive, reproducible and stable types were identified. The 12 Japanese isolates collected between 1992 and 1998 were of LRF type 11 suggesting that they were derived from the same source. The remaining eight isolates were of six types. The results indicate that LRF typing should be a useful technique for investigating the source and transmission of S equi.

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