A total of 55 isolates of bovine coronavirus (BCoV) were collected from cases of enteric and respiratory disease occurring between 1999 and 2006 in Japan. Molecular analysis of the polymorphic region of the S glycoprotein gene together with other known strains revealed that a phylogenetic tree classified all the BCoV strains and isolates into four clusters. Recent field isolates display distinctive genetic divergence from the prototype enteric bovine coronavirus (EBCoV) strains--Mebus, Quebec, Kakegawa, F15 and LY-138--and have diverged in three different aspects during eight years. These data suggested that the genetic divergence in the polymorphic region of S glycoprotein has progressed considerably; thus, molecular analysis of this region should be useful in investigating the molecular epidemiology of BCoV. In addition, based on the differences in amino acids among the isolates, our study did not reveal the presence of certain genetic markers of pathogenicity and clinical symptoms in this polymorphic region.
(Research Team for Environmental/Enzootic Diseases, Hokkaido Research Station, TEL +81-11-851-2132)
