1. Key Laboratory of Zoonosis, Institute of Zoonosis, Jilin University, Ministry of Education, Changchun, P. R. China.
2. Swedish Institute for Infectious Diseases Control, Stockholm, Sweden.
3. AFSSA, INRA, ENVA, UPVM, UMR 956 BIPAR, AFSSA LERPAZ, Maisons Alfort, France.