Classical Swine Fever
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CLASSICAL SWINE FEVER (CSF)
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Field diagnosis
Clinical materials
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Tonsils, lymph nodes (pharyngeal, mesenteric), spleen, kidney, distal part of ileum and blood in EDTA (live cases) are the ideal materials for isolation and identification of viruses. These materials should be kept under refrigeration and shipped to laboratory as quickly as possible
Direct identification of CSF from tissues
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Immunological methods
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Fluorescent antibody test (FAT) – Also known as fluorescent antibody tissue section test (FATST). It a rapid test that can be used to detect CSFV antigen in cryostat sections of tonsils, spleen, kidney, lymph nodes or distal portions of the ileum. Cryostat sections are stained directly with anti-CSF immunoglobulin conjugated to fluorescein isothiocyanate (FITC) or indirectly using a secondary FITC conjugate and examined by fluorescence microscopy.
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Immunoperoxidase test (IPT) – This test is used to differentiate between field strains of CSFV and vaccine strain of CSFV. A panel of three monoclonal antibodies (Mabs) are used to detect all field strains of CSFV, vaccine strains of CSFV and ruminant pestiviruses,
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Antigen capture ELISA (Double antibody sandwich ELISA) - Blood leukocyte fraction or anticoagulated whole blood or clarified tissue homogenate are used as antigen for ELISA. Monoclonal and polyclonal antibodies are used as detector and capture antibodies respectively. The technique is relatively simple to perform, does not require tissue culture facilities, is suitable for automation and can provide results within half a day. The disadvantage is less sensitive than virus isolation, especially in adult pigs and in mild or subclinical cases.
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RT-PCR - This method is rapid and more sensitive than antigen-capture ELISAs or virus isolation.
Isolation and identification
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Isolation of virus in cell cultures is a more sensitive but slower method for diagnosis of CSF. Isolation is best performed in rapidly dividing PK-15 cells. The cultures are examined for fluorescent foci by FAT after 24–72 hours.
Serological tests
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Detection of virus-specific antibodies is particularly useful on premises suspected of having infections with CSF strains of low virulence. Due to the immunosuppressive effect of CSFV, antibodies cannot be detected with certainty until 21 days post-infection. Commonly performed serological tests are as below. All the three tests are specified tests for international trade
Differential diagnosis
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Last modified: Wednesday, 30 March 2011, 4:48 AM
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