[1] Ctr Dis Control & Prevent, Div Viral Dis, Atlanta, GA USA
[2] Hungarian Acad Sci, Vet Med Res Inst, H-1581 Budapest, Hungary
[3] Chinese Acad Med Sci, Inst Lab Anim Sci, Beijing 100037, Peoples R China
[4] Peking Union Med Coll, Beijing 100021, Peoples R China