title: Characterization of virulence plasmids and serotyping of rhodococcus equi isolates from submaxillary lymph nodes of pigs in Hungary.
abstract: The plasmid types and serotypes of 164 Rhodococcus equi strains obtained from submaxillary lymph nodes of swine from different piggeries in 28 villages and towns located throughout the country were examined. The strains were tested by PCR for the presence of 15- to 17-kDa virulence-associated protein antigen (VapA) and 20-kDa virulence-associated protein antigen (VapB) genes. Plasmid DNAs were isolated and analyzed by digestion with restriction endonucleases to estimate size and compare their polymorphism characteristics. None of the 164 isolates contained the vapA gene, and 44 (26.8%) isolates were positive for the vapB gene, showing a product of the expected 827-bp size in the PCR amplification. The 44 isolates of intermediate virulence contained virulence plasmids that were identified as types 1 (3 isolates), 4 (1 isolate), 5 (36 isolates), 6 (1 isolate), and 7 (2 isolates) and as a new variant (1 isolate). On the basis of restriction digestion patterns of plasmid DNAs, we tentatively designated the variant as type 17. Use of the serotyping method of Prescott showed that 110 (67.1%) out of the 164 isolates were typeable and that serotype 2 predominated (83 isolates [50.6%]), followed by serotype 1 (26 strains [15.9%]). Only one isolate belonged to serotype 3. A total of 54 (32.9%) isolates were untypeable in Prescott's system. The prevalence of R. equi strains of intermediate virulence among the isolates that came from the submaxillary lymph nodes of swine in Hungary was lower than that seen with isolates obtained elsewhere.
authors.affiliation: Department of Microbiology and Infectious Diseases, Faculty of Veterinary Science, Szent István University, Hungária krt. 23-25, H-1143 Budapest, Hungary. Makrai.Laszlo@aotk.szie.hu
authors.forename: László
authors.initials: L
authors.lastname: Makrai
authors.forename: Saki
authors.initials: S
authors.lastname: Takayama
authors.forename: Béla
authors.initials: B
authors.lastname: Dénes
authors.forename: István
authors.initials: I
authors.lastname: Hajtós
authors.forename: Yukako
authors.initials: Y
authors.lastname: Sasaki
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Kakuda
authors.forename: Shiro
authors.initials: S
authors.lastname: Tsubaki
authors.forename: Andrea
authors.initials: A
authors.lastname: Major
authors.forename: László
authors.initials: L
authors.lastname: Fodor
authors.forename: János
authors.initials: J
authors.lastname: Varga
authors.forename: Shinji
authors.initials: S
authors.lastname: Takai
mesh_terms: D000818:Animals; D008198:Lymph Nodes / Q000382:microbiology*; D010957:Plasmids; D016929:Rhodococcus equi / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity; D012703:Serotyping; D013363:Submandibular Gland / Q000382:microbiology*; D013552:Swine / Q000382:microbiology*; D014774:Virulence