ABSTRACT
Objective To study the prevalence of the occult hepatitis B virus infection (OBI) and the mutation of amino acid sequence in S gene of voluntary blood donors in AnHui/FuJian/Jiang Xi Province Blood centers.Methods Serologic testing for anti-HBc by ELISA was performed with HBsAg-HBV DNA+ samples from voluntary blood donors in three province blood centers.The S region of HBV of those samples was amplified and sequenced.The genotype and mutation of amino acid sequence were analyzed by MEGA6.Results 21 in 123046 blood donors from AnHui Province blood center were HBsAgHBV DNA+,the prevalence of OBI was 0.017％,and 76.2％ of these-OBI samples was positive in anti-HBc,S region was amplified by nest-PCR in 15 OBI samples,8 of them were B genotype,the others were C genotype.39 samples of 51 OBI blood donors from FuJian Province blood center were anti-HBc positive,16 samples of those OBI donors were amplified S region,14 were B genotype,the others were C genotype.There are 30 OBI blood donors from JiangXi Province blood center,24 of them were anti-HBc positive,S region was amplified in 4 samples,1 was B genotype,the others were C genotype.Of all 35 OBI samples,26 showed amino acid mutation,which was in MHR region of S gene,especially in HBV α epitope.Conclusion The rate of prevalence of OBI in AnHui Province was 0.017％,there was also certain OBI infection in FuJian and JiangXi Province.In the OBI samples which were amplified S region,the positive rates of anti-HBc in three blood centers were 73.3％,93.8％,100％.B Genotype was the main HBV genotype.The mutation in MHR region of S gene,especially in HBV α epitope,may be one of the reasons to cause OBI.
ABSTRACT
Objective To analyze the mutation of PreS-S region in occult hepatitis B virus(OHBV) in HBV infected persons with positive HBsAb and investigate the biological mechanisms of the special infectious model.Methods A total of 38 HB-sAb positive OBI serum samples were amplified by Nested PCR and sequenced,HBV genotype and serotype were determined.The amino acid sequences of OHBV were compared to the corresponding sequence of wild-type strains of similar genotype obtained from the GenBank database.Results PreS-S segment of 11 samples were obtained and 8 samples were sequenced successfully.Among which,5 were genotype C and 3 were genotype B.Genotype B were all serotype adw,while genotype C were 1 adw and 4 adr.The mutation rates of PreS-S region,the immunoreactive area and the major hydrophilic region (MHR) were higher in OHBV than the wild-type strains (2.6％ vs 0.8％,x2 =40.23,3.2％ vs 0.3％,x2 =52.13,3.6％ vs 0.6％,x2 =13.25,all P＜0.01) and the substitutions of I126T,Q129R,M133T,F134I,D144E,G145K in α determinant were found in OBI samples.The mutation rate of amino acids in PreS-S region was higher in genotype C than genotype B (3.5％ vs 1.2％,x2--15.98,P＜0.01),meanwhile,the mutation rates in MHR,α determinant and immunoreactive region were higher in genotype C too,but no statistical significance was attained (4.7％ vs 1.7 ％,x2 =2.96,3.6 ％ vs 2.9％,x2 =0.25,4.1％ vs 2.3％,x2 =3.59,all P ＞0.05).Conclusion Mutations in PreS-S region,especially in immunoepitope,might change the virus'immunogenicity leading to escape from immune response and cause OBI with HBsAb positive.