Systematic Veterinary Virology

LABORATORY DIAGNOSIS

• Isolation and identification
• Clinical materials: Samples should be collected from sick or freshly dead birds.
• Fresh bursa and spleen for virus isolation.
• Samples of bursa, spleen, intestines, caecal tonsil, liver and kidney should be collected in neutral buffered formalin for histopathology
• Blood samples for serology.
• Isolation systems: Chickens, ECE and Chicken embryo fibroblast (follow as given under cultivation).
• Direct identification of antigen from bursa
• Agar gel immunodiffusion test
• Immunofluorescense test
• Antigen capture ELISA
• RT-PCR
• Strain differentiation
• IBDV serotypes are differentiated by cross neutralization virus neutralization test or by serological tests using serotype specific monoclonal antibodies.
• Pathotype identification
• The terms ‘variant’, ‘classical’ and ‘very virulent’ have been used to qualify IBDV strains that exhibit a different pathogenicity. Based on the signs and lesions observed in White Leghorn SPF chickens during acute experimental IBD
• ‘Variant’ IBDVs induce little if any clinical signs and no mortality but marked bursal lesions,
• ‘Classical’ IBDVs induce approximately 10–50% mortality with typical signs and lesions
• ‘Very virulent’ IBDVs induce approximately 50–100% mortality with typical signs and lesions