作者单位:Natl Inst Infect Dis, Pathogen Genom Ctr, Tokyo, Japan[1]Ohio State Univ, Ohio Agr Res & Dev Ctr, Coll Food Agr & Environm Sci, Food Anim Hlth Res Program,Dept Vet Prevent Med, Wooster, OH 44691 USA[2]Kansas State Univ, Coll Vet Med, Dept Diagnost Med & Pathobiol, Manhattan, KS 66506 USA[3]