Systematic Veterinary Virology

LABORATORY DIAGNOSIS

• Clinical materials to be collected
• Tears: Cotton buds or swabs of absorbent cotton wool are inserted into the conjunctival sac and swirled around to collect tears. The bud/swab is broken off into a container and about 150 microlitres of sterile phosphate-buffered saline (PBS pH 7.2 to 7.6)
• Gum debris: This material can be collected by a spatula or finger rubbed across the gum and inside the upper and lower lips. The material collected is then scraped into a container and 150 microlitres of PBS are added
• Tissues: Tissue to be collected are from lymph nodes found around the lungs (mediastinal) and alimentary tract (mesenteric); portions of the spleen and the lungs. Two sets of each tissue are required; one set is chilled but not frozen, and the other is put in 10 percent formalin solution to preserve the samples
• Unclotted blood: This is needed for virus isolation and should be collected in bottles containing anticoagulants (heparin or ethylenediamine tetracetic acid [EDTA]).
• Clotted blood or serum: For identification of antiboies
• Isolation and identification
• The tissue culture used are lamb kidney cells and Vero cells. The characteristic CPE appear around 5th day and are cell rounding and aggregation and syncytia formation
• Identification of virus
• Immunocapture enzyme-linked immunosorbent assay (Sandwich ELISA)
• Counterimmunoelectrophoresis (CIEP): Most rapid test for detecting viral antigen
• Agar gel immunodiffusion (AGID): Very simple and inexpensive and gives results within 1 day, but not sensitive to mild forms of PPR
• Immunofluorescence and immunoperoxidase
• Polymerase chain reaction (RT-PCR)
• Nucleic acid probes