1. Dongfeng Stomatological Hospital, Hubei University of Medicine, Shiyan, Hubei 442000, P.R. China
2. Department of Pathogen Biology, College of Basic Medical Sciences, Wuhan, Hubei 430060, P.R. China
3. Department of Pathology, Renmin Hospital, Wuhan University, Wuhan, Hubei 430060, P.R. China