A rapid-plate hemagglutination assay for the detection of infectious bronchitis virus.

A rapid-plate hemagglutination (HA) test to detect infectious bronchitis virus (IBV) in allantoic fluid of embryonated eggs was introduced into routine procedures for IBV identification. This system was tested in 468 diagnostic cases received by the Poultry Diagnostic and Research Center at the University of Georgia. Allantoic fluids from inoculated embryos were harvested and treated with commercially available neuraminidase enzyme. IBV in neuraminidase-treated allantoic fluid was identified by clear and consistent HA of chicken red blood cells within 1 min of incubation. The specificity of the neuraminidase rapid-plate HA assay was examined with other avian viruses in individual and dual embryonic infections. Sensitivity of this test was compared with embryo lesions and reverse transcriptase-polymerase chain reaction (RT-PCR). The rapid-plate HA assay of neuraminidase-treated allantoic fluid correlated with the RT-PCR during the early stages of IBV detection, identification, and isolation in embryonated eggs.