Systematic Veterinary Virology

Laboratory Diagnosis - Direct identification of CSF from tissues

DIRECT IDENTIFICATION OF CSF FROM TISSUES

• Immunological methods
  • 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.
  • 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.
  • 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.
• RT-PCR
• This method is rapid and more sensitive than antigen-capture ELISAs or virus isolation.