Typing of infectious bronchitis virus (IBV) and relationship to protection in poultry

This study deals with the detection and differentiation of infectious bronchitis virus (IBV) strains present in New Zealand, describes pathology caused by field strains and evaluates protection given by an attenuated live vaccine. Four historic (A, B, C and D) and five recent (T6, K32, K43, T75 and K87) IBV strains were used in the study. A rapid detection system for the virus based on a reverse transcriptase polymerase chain reaction (RT-PCR) assay was developed which has proved to be at least as sensitive as virus isolation. This assay can detect virus directly from the tissues thus removing the need to culture diagnostic samples in embryonated eggs or tracheal organ cultures (TOC). Viral RNA could be detected from infected allantoic fluid at levels