[1] Robert Koch Inst, Ctr Biol Threats & Special Pathogens 1, Seestr 10, D-13353 Berlin, Germany
[2] Free Univ Berlin, Inst Virol, Dept Vet Med, Robert von Ostertag Str 7-13, D-14163 Berlin, Germany
[3] City Univ Hong Kong, Jockey Club Coll Vet Med & Life Sci, Dept Infect Dis & Publ Hlth, Kowloon, Hong Kong, Peoples R China