1. Department of Infectious Diseases; The Second Affiliated Hospital of Xi'an Jiaotong University; Xi'an Shaanxi P. R. China
2. Department of Infectious Diseases; Central Hospital of Xianyang City; Shaanxi Province, Xianyang Shaanxi P. R. China
3. Department of Biochemistry and Molecular Biology; Medical College of Xi'an Jiaotong University; Xi'an Shaanxi P. R. China