Abstract: Ｏｂｊｅｃｔｉｖｅ：To assess the molecular characteristic and prognosis of occult hepatitis B infection (OBI) in maintenance hemodialysis (MHD) patients in Sichuan Province of China.
Ｍｅｔｈｏｄｏｌｏｇｙ：A 2year followup study of 7 MHD patients with OBI were conducted.Serum samples were collected for ELISA assay to test  serological markers of HBV infection,and realtime PCR assay to identify  presence of HBVDNA,and nested PCR plus sequencing analysis to investigate  genotype of HBV and  gene mutations of S gene.
Ｒｅｓｕｌｔｓ：After 2years of followed,2 fo the 7 MHDOBI patients were unfortunately died.Serum amples from 3 patients that were HBsAg-/HBsAb+/HBcAb+ before,were not able to detect HBVDNA again.The other 2 were still positive of HBVDNA (<20 IU/ml).By nested PCR and sequencing analysis,it′s found that these two patients were genotype B. Further amino acid analysis revealed that patient No2 did not carry any amino acid mutation in  “a” determinant. However,patient No6 was found to have mutations of Q129R,T131N,M133S,F134L and D144E,which were localized at  “a” determinant of HBsAg. The Q129R and M133S mutations were first reported.
Ｃｏｎｃｌｕｓｉｏｎ：Our study reveals that  prevalence of OBI in MHD patients were still positive in serological markers. The major genotype is B. We first demonstrate  mutations of Q129R and M133S in  “a” determinant of HBsAg. These findings indicate the importance of HBVDNA examination in  MHD patients.