| isolation of 4/91 type of infectious bronchitis virus as a new variant in japan and efficacy of vaccination against 4/91 type field isolate. | among field isolates of infectious bronchitis virus (ibv) from recent outbreaks, some isolates that were classified into the 4/91 genotype, by analysis of the s1 gene, have been confirmed to be a new variant in japan. to elucidate the characteristics of these isolates, pathogenicity in chicks and the efficacy of vaccines against this new variant were examined. severe respiratory symptoms were observed in 4-day-old specific pathogen free chicks inoculated with a 4/91 genotype isolate, either jp/w ... | 2008 | 19166052 |