title: Comparative studies on the pathogenicity and tissue distribution of three virulence variants of classical swine fever virus, two field isolates and one vaccine strain, with special regard to immunohistochemical investigations.
abstract: BACKGROUND
  The aim of this study was to compare the tissue distribution and pathogenicity of three virulence variants of classical swine fever virus (CSFV) and to investigate the applicability of various conventional diagnostic procedures.
  
  
  METHODS
  64 pigs were divided into three groups and infected with the highly virulent isolate ISS/60, the moderately virulent isolate Wingene'93 and the live attenuated vaccine strain Riems, respectively. Clinical signs, gross and histopathological changes were compared in relation to time elapsed post infection. Virus spread in various organs was followed by virus isolation, by immunohistochemistry, applying monoclonal antibodies in a two-step method and by in situ hybridisation using a digoxigenin-labelled riboprobe.
  
  
  RESULTS
  The tissue distribution data are discussed in details, analyzing the results of the various diagnostic approaches. The comparative studies revealed remarkable differences in the onset of clinical signs as well as in the development of the macro- and microscopical changes, and in the tissue distribution of CSFV in the three experimental groups.
  
  
  CONCLUSIONS
  The present study demonstrates that in the case of highly and moderately virulent virus variants the virulence does not affect the pattern of the viral spread, however, it influences the outcome, the duration and the intensity of the disease. Immunohistochemistry has the advantage to allow the rapid detection and localisation of the virus, especially in cases of early infection, when clinical signs are still absent. Compared to virus isolation, the advantage of this method is that no cell culture facilities are required. Thus, immunohistochemistry provides simple and sensitive tools for the prompt detection of newly emerging variants of CSFV, including the viruses of very mild virulence.
authors.affiliation: Department of Virology, National Veterinary Institute, Uppsala, Sweden. katinka@belak.se
authors.forename: Katinka
authors.initials: K
authors.lastname: Belák
authors.forename: Frank
authors.initials: F
authors.lastname: Koenen
authors.forename: Hans
authors.initials: H
authors.lastname: Vanderhallen
authors.forename: Christian
authors.initials: C
authors.lastname: Mittelholzer
authors.forename: Francesco
authors.initials: F
authors.lastname: Feliziani
authors.forename: Gian Mario
authors.initials: GM
authors.lastname: De Mia
authors.forename: Sándor
authors.initials: S
authors.lastname: Belák
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D000940:Antigenic Variation; D006691:Classical Swine Fever / Q000378:metabolism / Q000473:pathology / Q000821:virology*; D006692:Classical Swine Fever Virus / Q000302:isolation & purification / Q000378:metabolism / Q000472:pathogenicity*; D019085:Fluorescent Antibody Technique, Direct / Q000662:veterinary; D007150:Immunohistochemistry / Q000662:veterinary; D017403:In Situ Hybridization / Q000662:veterinary; D008198:Lymph Nodes / Q000473:pathology / Q000821:virology; D013154:Spleen / Q000473:pathology / Q000821:virology; D013552:Swine; D014774:Virulence
chemical_list: D000914:Antibodies, Viral
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