Abstract
Eighteen isolates of infectious bronchitis virus (IBV) from Italy and Poland in 1997 to 1998 were comprehensively analysed by serum haemagglutination inhibition and virus neutralization tests, and by type-specific polymerase chain reactions and spike protein S1 gene sequencing. Four types of IBV (793/B, 624/I, B1648 and Massachusetts) were detected in Italy, while the presence of 793/B was confirmed in Poland. This showed that not only were four types of IBV co-existing within a single year, but also that several types of IBV have persisted in Europe for many years (at least 13 to 14 years for types B1648 and 793/B). Sequencing of the S1 gene of the 624/I isolate confirmed this as a unique type of IBV.