Classification of IBV S1 Genotypes by Direct Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) and Relationship between Serotypes and Genotypes of Strains Isolated between 1998 and 2008 in Japan

摘要

In this study, we attempted to establish a simple detection method for classification of IBV S1 genotypes by direct reverse transcriptase-polymerase chain reaction (RT-PCR). Then, to evaluate the usefulness of the S1 genotype-specific RT-PCR, we examined the relationship between SI genotypes and serotypes of IBV in Japan. Sequencing of the SI genes of IBV and phylogenetic tree analysis were conducted. On the basis of the sequencing data of the SI genotype samples, we determined primer sets specific for each genotype. Five vaccine strains in Japan as reference strains and 46 field isolates were classified into different genetic clusters by phylogenetic tree analysis (JP-I, JP-II, JP-III, Mass and 4/91) and were matched to the results of SI genotype-specific RT-PCR. A cross virus-neutralizing test showed that the five vaccine strains in Japan exhibited different serotypes from each other. The concordance rate of the 46 field isolates between the S I genotypes and serotypes was 65.2%. The present study indicates that genotype-specific RT-PCR could be a convenient and useful tool for determining IBV serotypes and could contribute to the control of IBV outbreaks in Japan.