Systematic Veterinary Virology

LABORATORY DIAGNOSIS

Isolation and identification

• Samples from dead birds: Intestinal contents (faeces) or cloacal swabs, oro-nasal swabs, trachea, lungs, air sacs, intestine, spleen, kidney, brain, liver and heart are the ideal material.
• Samples from tracheal and cloacal swabs.
• The samples should be placed in isotonic phosphate buffered saline (PBS), p^H 7.0–7.4, containing antibiotics, processed, centrifuged and the supernatant is inoculated in 9-11 day old embryonated eggs. The eggs should be incubated for 4 days at 35-37^ºC. The presence of virus in allantoic fluid are confirmed by
• Detection of HA activity
• Agar gel immunodiffusion (AGID) test - by demonstrating the presence of the nucleocapsid or matrix antigens
• RT-PCR
• Antigen capture ELISA
• RT-PCR can also be used to identify viral RNA directly in the clinical samples without passaging the materials in embryonated eggs.