title: Rhodococcus equi virulence plasmids recovered from horses and their environment in Jeju, Korea: 90-kb type II and a new variant, 90-kb type V.
abstract: Rhodococcus equi was isolated from fecal and soil samples from four native Jeju horse farms and six Thoroughbred farms in Jeju, Korea. The isolates were examined for the presence of virulence-associated 15-17-kDa antigens (VapA) by colony blotting, using the monoclonal antibody 10G5, and for the gene encoding VapA by PCR. R. equi was isolated from all 36 soil samples collected from the 10 farms with between 5.0 x 10(2) and 7.5 x 10(4) colony-forming units (cfu) per gram of soil, and from 37 of 40 fecal samples with between 5.0 x 10(1) and 1.1 x 10 (5) cfu per gram of feces. Virulent R. equi was isolated from seven farms and appeared in 2.0% of isolates (10 of 508). Of the 10 virulent isolates, four contained a 90-kb type II plasmid, which has been found in isolates from the Kiso native horses of Japan, and the other six contained a new variant, which did not display the EcoRI and EcoT22I digestion patterns of the 10 representative plasmids already reported (85-kb types I, II, III, and IV; 87-kb types I and II; 90-kb types I, II, III, and IV). We designated the new variant as the "90-kb type V" plasmid, because its EcoRI digestion pattern is similar to that of the 90-kb type II plasmid. This is the first report of the prevalence of virulent R. equi in Jeju, Korea. The same virulence plasmid type is found in both Korean and Japanese isolates, providing insight into the origin, ancestry, and dispersal of native horses in Korea and Japan.
authors.affiliation: Department of Animal Hygiene, School of Veterinary Medicine and Animal Sciences, Kitasato University, Aomori, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Takai
authors.forename: Won-Geun
authors.initials: WG
authors.lastname: Son
authors.forename: Du-Sik
authors.initials: DS
authors.lastname: Lee
authors.forename: Hiroo
authors.initials: H
authors.lastname: Madarame
authors.forename: Izumi
authors.initials: I
authors.lastname: Seki
authors.forename: Noriko
authors.initials: N
authors.lastname: Yamatoda
authors.forename: Ayumi
authors.initials: A
authors.lastname: Kimura
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Kakuda
authors.forename: Yukako
authors.initials: Y
authors.lastname: Sasaki
authors.forename: Shiro
authors.initials: S
authors.lastname: Tsubaki
authors.forename: Yoon-Kyu
authors.initials: YK
authors.lastname: Lim
mesh_terms: D000193:Actinomycetales Infections / Q000662:veterinary*; D000818:Animals; D014644:Genetic Variation; D006734:Horse Diseases / Q000382:microbiology*; D006736:Horses; D007564:Japan; D007723:Korea; D010957:Plasmids / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction; D015183:Restriction Mapping; D016929:Rhodococcus equi / Q000235:genetics / Q000472:pathogenicity; D012988:Soil Microbiology; D014774:Virulence / Q000235:genetics*