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.
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.
Belák
Katinka
K
Department of Virology, National Veterinary Institute, Uppsala, Sweden. katinka@belak.se
Koenen
Frank
F
Vanderhallen
Hans
H
Mittelholzer
Christian
C
Feliziani
Francesco
F
De Mia
Gian Mario
GM
Belák
Sándor
S
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
D000914:Antibodies, Viral
Vet Rec. 1996 Oct 12;139(15):367-71
8903020
Vet Pathol. 2006 Jul;43(4):530-40
16846995
Vet Microbiol. 2000 Apr 13;73(2-3):131-6
10785323
Zentralbl Veterinarmed B. 1973 Jun;20(4):256-71
4751661
Am J Vet Res. 1969 Mar;30(3):409-17
4179763
J Virol Methods. 1998 Sep;74(1):47-56
9763128
Arch Exp Veterinarmed. 1987 Nov;41(6):841-5
3442453
Dtsch Tierarztl Wochenschr. 2006 Apr;113(4):134-8
16716047
Comp Immunol Microbiol Infect Dis. 1992 Jul;15(3):203-11
1516362
Arch Virol. 1997;142(8):1613-34
9672623
Zentralbl Veterinarmed B. 1997 Jul;44(5):281-6
9270350
Aust Vet J. 1992 Oct;69(10):240-4
1445070
Expert Rev Mol Diagn. 2001 Nov;1(4):434-43
11901858
Vet Pathol. 2000 Sep;37(5):402-8
11055862
Comp Immunol Microbiol Infect Dis. 1999 Jul;22(3):207-20
10391508
Prev Vet Med. 1999 Dec 1;42(3-4):157-84
10619154
Tijdschr Diergeneeskd. 1985 Apr 1;110(7):263-9
3992564
Vet Pathol. 2003 May;40(3):254-62
12724565
Vet Pathol. 2003 Jan;40(1):107-13
12627722
Zentralbl Veterinarmed B. 1973 Jun;20(4):272-88
4751662