A NOVEL PROTEIN POLYMORPHISM DIFFERENTIATES THE CALIFORNIA SEROTYPE OF INFECTIOUS-BRONCHITIS FROM OTHER SEROTYPES COMMON TO CALIFORNIA

The California (Cal) serotype of infectious bronchitis virus (IBV) was isolated from layer flocks in southern California in the early 1980s. Since then, it has spread to the broiler-producing regions of central California, where it has been implicated in respiratory disease outbr eaks in vaccinated flocks. Lack of a procedure for quickly identifying IBV serotypes in commercial chicken flocks has prevented the causal a ssociation of the IBV Cal serotype with respiratory disease outbreaks. A protein polymorphism has been identified in the matrix protein of t he Cal serotype; it appears to be unique among other common serotypes of infectious bronchitis virus found in California. This polymorphism can be identified on western blots using raw or concentrated infectiou s allantoic fluid as the source material. Identification of the Cal se rotype and of serotypes in the Mass and Conn groups can be performed r apidly using field samples from suspect flocks. The identification of this polymorphism provides an alternative method for the rapid identif ication of the Cal serotype of IBV.