Linked PNPLA3 polymorphisms confer susceptibility to nonalcoholic steatohepatitis and decreased viral load in chronic hepatitis B

AIM: To investigate the association of PNPLA3 polymorphisms with concurrent chronic hepatitis B (CHB) and nonalcoholic fatty liver disease (NAFLD).METHODS: A cohort of Han patients with biopsy-proven CHB, with or without NAFLD (CHB group, n = 51; CHB + NAFLD group, n = 57), and normal controls (normal group, n = 47) were recruited from Northern (Tianjin), Central (Shanghai), and Southern (Zhangzhou) China. Their PNPLA3 polymorphisms were genotyped by gene sequencing. The association between PNPLA3 polymorphisms and susceptibility to NAFLD, and clinical characteristics of NAFLD were evaluated on the basis of physical indices, liver function tests, glycolipid metabolism, and histopathologic scoring. The association of PNPLA3 polymorphisms and hepatitis B virus (HBV) load was determined by the serum level of HBV DNA.RESULTS: After adjusting for age, sex, and body mass index, we found that four linked single nucleotide polymorphisms (SNPs) of PNPLA3, including the rs738409 G allele (CHB + NAFLD group vs CHB group: odds ratio [OR] = 2.77, 95% confidence interval [CI]: 1.18-6.54; P = 0.02), rs3747206 T allele (CHB + NAFLD group vs CHB group: OR = 2.77, 95%CI: 1.18-6.54; P = 0.02), rs4823173 A allele (CHB + NAFLD group vs CHB group: OR = 2.73, 95%CI: 1.16-6.44; P = 0.02), and rs2072906 G allele (CHB + NAFLD group vs CHB group: OR = 3.05, 95%CI: 1.28-7.26; P = 0.01), conferred high risk to NAFLD in CHB patients. In patients with both CHB and NAFLD, these genotypes of PNPLA3 polymorphisms were associated with increased susceptibility to nonalcoholic steatohepatitis (NASH) (NAFLD activity score ≥ 3; P = 0.01-0.03) and liver fibrosis (> 1 Metavir grading; P = 0.01-0.04). As compared to those with C/C and C/G at rs738409, C/C and C/T at rs3747206, G/G and G/A at rs4823173, and A/A and A/G at rs2072906, patients in the CHB + NAFLD group with G/G at rs738409, T/T at rs3747206, A/A at rs4823173, and G/G at rs2072906 showed significantly lower serum levels of HBV DNA (P < 0.01-0.05).CONCLUSION: Four linked SNPs of PNPLA3 (rs738409, rs3747206, rs4823173, and rs2072906) are correlated with susceptibility to NAFLD, NASH, liver fibrosis, and HBV dynamics in CHB patients.     

Controversial issues regarding the roles of IL-10 and IFN-γ in active/inactive chronic hepatitis B

According to the important roles played by cytokines in induction of appropriate immune responses against hepatitis B virus(HBV),Dimitropoulou et al have examined the important cytokines in their patients.They showed that the serum levels of interleukin 10(IL-10)and interferon-γ(IFN-γ)were decreased in patients with HBeAg-negative chronic active hepatitis B compared with the inactive hepatitis B virus carriers(Dimitropoulou et al 2013).The controversy can be considered regarding the decreased serum levels of IFN-γin the HBeAg-negative chronic active hepatitis B patients.They concluded that subsequent to decreased expression of IFN-γ,the process of HBV proliferation led to liver diseases.Previous studies stated that HBV is not directly cytopathic for the infected hepatocytes and immune responses are the main reason for destruction of hepatocytes(Chisari et al,2010).Scientists believe that immune responses against HBV are stronger in active forms of chronic HBV infected patients than inactive forms(Zhang et al,2012).Therefore,the findings from Dimitropoulou et al may deserve further attention and discussion.Additionally,downregulation of IL-10 inchronically active hepatitis B infected patients has also confirmed our claim.IL-10 is an anti-inflammatory cytokine and its expression is increased in inactive forms in order to downregulate immune responses(Arababadi et al,2012).Thus,based on the results from Dimitropoulou et al,it can be concluded that increased immune responses in chronically active hepatitis B infected patients are related to declined expression of IL-10 and interestingly IFN-γis not involved in induction of immune responses in these patients.     

表面抗原和抗体双阳性慢性乙型肝炎病毒感染者病毒S基因的变异分析

目的 了解HBsAg和抗-HBs双阳性慢性HBV感染者的S基因变异情况.方法 分别对8例HBsAg和抗-HBs双阳性(实验组)及9例HBsAg阳性、抗-HBs阴性慢性HBV感染者(对照组)的S基因进行PCR扩增并测序,将测序结果进行对比分析.基因型和血清型分布比较、主要亲水区变异位点数比较采用Fisher'S精确检验,核苷酸和氨基酸序列的同源性比较采用t检验.结果 感染HBV的基因型分布:实验组为B型2例、C型6例,对照组为B型6例、C型3例,两组间差异无统计学意义(P>0.05);血清型分布:实验组为adw 2例、adr 5例、ayr 1例,对照组为adw 6例、adr 3例,两组间差异无统计学意义(P>0.05).实验组和对照组HBV前S1区的核苷酸替换率(2.29%比1.8%)和氨基酸替换率(2.66%比1.59%)差异无统计学意义(t值分别为1.56和1.39,P值均>0.05),前S2区的核苷酸替换率(1.74%比0.91%)差异有统计学意义(t=4.68,P<0.01),氨基酸替换率(3.18%比2.05%)差异无统计学意义(t=1.85,P>0.05);S区的核苷酸替换率(2.13%比0.81%)和氨基酸替换率(4.37%比1.52%)差异有统计学意义(t值分别为6.00和5.32,P值均<0.01).主要亲水区内外均存在氨基酸的替换,"a"决定簇变异相对较高(P<0.05).结论 HBsAg和抗-HBs双阳性慢性HBV感染者的S基因变异率相对较高.     

Relationship between cytokine gene polymorphisms and chronic hepatitis B virus infection

Hepatitis B virus (HBV) infection is still a public health problem worldwide, being endemic in some parts of the world. It can lead to serious liver diseases such as chronic hepatitis, cirrhosis, and hepatocellular cancer. The differences in host immune response can be one of the reasons for the various clinical presentations of HBV infection. Polymorphisms of genes encoding the proinflammatory and antiinflammatory cytokines, which are responsible for regulation of the immune response, can affect the clinical presentation of the infection. Particularly, the polymorphisms of the genes encoding cytokines such as interleukin (IL)-1, IL-6, IL-8, IL-10, IL-18, IL-28B, interferon-γ, tumor necrosis factor-α, tumor growth factor-β1, and regulatory molecules like vitamin D receptor and chemokine receptor 5 can be responsible for different clinical presentations of HBV infections. The genomic information about cytokines and other mediators can be important for determining high-risk people for developing chronic hepatitis or hepatocellular cancer and may be used to plan treatment and preventive approaches for these people. In this review, the current knowledge in the literature on the association between cytokine/regulatory molecule gene polymorphisms and clinical course of chronic HBV infection is summarized, and the clinical implementations and future prospects regarding this knowledge are discussed.     

Mechanism of T cell hyporesponsiveness to HBcAg is associated with regulatory T cells in chronic hepatitis B

AIM: To study the mechanisms of hyporesponsiveness of HBV-specific CD4 T cells by testing TH1 and TH2 commitment and regulatory T cells. METHODS: Nine patients with chronic hepatitis B were enrolled. Peripheral blood mononuclear cells were stimulated with HBcAg or HBsAg to evaluate their potential to commit to TH1 and TH2 differentiation. HBcAg-specific activity of regulatory T cells was evaluated by staining with antibodies to CD4, CD25, CTLA-4 and interleukin-10. The role of regulatory T cells was further assessed by treatment with anti-interleukin-10 antibody and depletion of CD4 CD25 cells. RESULTS: Level of mRNAs for T-bet, IL-12R p2 and IL-4 was significantly lower in the patients than in healthy subjects with HBcAg stimulation. Although populations of CD4 CD25highCTLA-4 T cells were not different between the patients and healthy subjects, IL-10 secreting cells were found in CD4 cells and CD4 CD25 cells in the patients in response to HBcAg, and they were not found in cells which were stimulated with HBsAg. Addition of anti-IL-10 antibody recovered the amount of HBcAg-specific TH1 antibody compared with control antibody (P < 0.01, 0.34%±0.12% vs 0.15%±0.04%). Deletion of CD4 CD25 T cells increased the amount of HBcAg-specific TH1 antibody when compared with lymphocytes reconstituted using regulatory T cells (P < 0.01, 0.03%±0.02% vs 0.18%±0.05%). CONCLUSION: The results indicate that the mechanism of T cell hype-responsiveness to HBcAg includes activation of HBcAg-induced regulatory T cells in contrast to an increase in TH2-committed cells in response to HBsAg.     

补体C5基因多态性与肝硬化发病的关系研究

目的探讨补体C5基因多态性与肝硬化发生的关系。方法慢性乙型肝炎和乙型肝炎肝硬化患者182例,提取白细胞DNA,采用Taqman实时PCR法进行C5基因rs17611位点的多态性基因型检测。结果在182例患者中,基因型为GG型者83例（45.6%）,AG型者79例（43.4%）,AA型者20例（11.0%）;肝硬化患者C5基因rs17611位点AA基因型检出率较高;多元Logistic回归分析显示AA基因型是肝硬化发生的独立危险因子（OR=5.1,P=0.008）。结论补体C5基因多态性可能与乙型肝炎病毒感染者发生肝硬化有关。     

Relationship between interleukin 18 polymorphisms and susceptibility to chronic hepatitis B virus infection

AIM:To identify the relationship between the tagging single nucleotide polymorphism sites(tagSNPs)of the Interleukin-18(IL-18)gene and genetic susceptibility to chronic hepatitis B virus infection in Chinese patients.METHODS:Five hundred and one cases of chronic hep-atitis B virus(HBV)infection and 301 HBV natural clearance controls were studied.Two tagSNPs in the IL-18 gene(rs1946518A/C and rs574424C/G)were genotyped by the Multiplex Snapshot technique.The genotype and allele frequencies were calculated and analyzed.RESULTS:In the genotypes of rs1946518,the AA type was present at a higher frequency in the patients compared to those in the controls.Odds ratio(OR)of theAA genotype for the comparison with that of the AC and the CC genotype was 1.537(95%confidence intervals(CI):1.116-2.218,P=0.009<0.025).In pheno-types,the allele C at rs1946518 was of a significantly lower frequency in the patients with chronic hepatitis B than that in the controls(P=0.017<0.025).OR of the allele A for the comparison with that of the allele C was 1.279(95%CI:1.045-1.567).As for the rs574424 genotypes,no significant difference in this genotype distribution or in this allele frequency between the patients and the control subjects was observed.No significant difference in the haplotype frequencies between the patients with chronic hepatitis B and HBV natural clearance individuals was displayed.CONCLUSION:The data suggest that genotype AA and the allele A of the IL-18 at position rs1946518 are closely associated with the resistance to chronic hepatitis B and may be the dangerous gene.However,no statistical association was found between polymorphisms of rs574424 for IL-18 and hepatitis B.     

乙型肝炎基因治疗的研究进展

基因治疗是指通过基因水平的操纵达到治疗或预防疾病的疗法,分体内疗法和体外疗法.前者是将外源基因直接导入人体发挥作用;     

慢性乙型肝炎患者HBV基因型和哑型分布调查

目的研究慢性乙型肝炎患者HBV基因型和亚型流行情况。方法应用HBV基因型和亚型特异性引物PCR法对北京、长春、大连、西安、石家庄、郑州和合肥7个城市660份HBV DNA阳性慢性乙型肝炎患者血清进行基因型和亚型分析。结果在660份HBV DNA阳性血清中,B基因型、C基因型和B／C混合感染分别为16．67％（110／660）、74．54％（492／660）和8．79％（58／660）;在C基因型中,C1亚型6例（1．22％）、C2亚型473例（96．14％）、C1／C2混合基因亚型13例（2．64％）;B基因型均为Ba亚型,B基因型和C基因型混合感染者均为Ba与C2亚型混合感染,未发现其他基因型和基因亚型;不同基因型感染患者HBeAg阳性率差异无统计学意义（P=0．153）;B基因型和C基因型患者之间血清HBV DNA水平差异无统计学意义（6．37±1．62lg copies／ml对6．29±1．76lg copies／ml）,但均高于B和C基因型混合感染患者（5．25±1．65lg copies／ml）。结论这7个城市慢性乙型肝炎患者以B基因型和C基因型感染为主,有部分B／C基因型混合感染。HBV亚型以Ba和C2亚型占优势。     

Relationship between hepatitis B virus DNA levels and liver histology in patients with chronic hepatitis B

AIM： To study the relationship between hepatitis B virus （HBV） DNA levels and liver histology in patients with chronic hepatitis B （CHB） and to determine the prevalence and characteristics of hepatitis B e antigen （HBeAg） negative patients.
METHODS： A total of 213 patients with CHB were studied, and serum HBV DNA levels were measured by the COBAS Amplicor HBV Monitor test. All patients were divided into two groups according to the HBeAg status.The correlation between serum HBV DNA levels and liver damage （liver histology and biochemistry） was explored.
RESULTS： Of the 213 patients with serum HBV DNA levels higher than 10^5 copies/mL, 178 （83.6%） were HBeAg positive, 35 （16.4%） were HBeAg negative. The serum HBV DNA levels were not correlated to the age,history of CHB, histological grade and stage of liver disease in either HBeAg negative or HBeAg positive patients. There was no correlation between serum levels of HBV DNA and alanine aminotransferanse （ALT）,aspartate aminotrans-ferase （AST） in HBeAg positive patients. In HBeAg negative patients, there was no correlation between serum levels of HBV DNA and AST,while serum DNA levels correlated with ALT （r = 0.351, P = 0.042）. The grade （G） of liver disease correlated with ALT and AST （P 〈 0.05, r = 0.205, 0.327 respectively）in HBeAg positive patients. In HBeAg negative patients,correlations were shown between ALT, AST and the G （P 〈 0.01, and r = 0.862, 0.802 respectively）. HBeAg negative patients were older （35 ± 9 years vs 30 ±9 years, P 〈 0.05 ） and had a longer history of HBV infection （8 ± 4 years vs 6 ± 4 years, P 〈 0.05） and a lower HBV DNA level than HBeAg positive patients （8.4± 1.7 Log HBV DNA vs 9.8 ± 1.3 Log HBV DNA, P 〈0.001）. There were no significant differences in sex ratio,ALT and AST levels and liver histology between the two groups.
CONCLUSION： Serum HBV DNA level is not correlated to histological grade or stage of liver disease in CHB patients with HBV DNA mor     

慢性乙型肝炎患者肝细胞内乙型肝炎核心抗原阳性的临床意义

目的探讨CHB患者肝组织HBcAg阳性的意义。方法对200例CHB患者应用荧光聚合酶链反应（FQ-PCR）法精确定量检测血清HBV DNA含量。患者均检测血清中HBeAg含量,同时进行肝活组织检查,应用免疫组织化学技术检测HBcAg情况,并进行相关性分析。结果按测定血清HBV DNA水平,分为A组（＜3 log10拷贝/ml）20例,B组（≥3 log10拷贝/ml-＜5 log10拷贝/ml）13例,C组（≥5 log10拷贝/ml～＜6 log10拷贝/ml）24例,D组（≥6 log10拷贝/ml～＜8 log10拷贝/ml）116例,E组（≥8 log10拷贝/ml）27例。肝组织HBcAg阳性者175例,占87．5％,A组HBcAg阳性率55．0％（11/20）,B组53．8％（7/13）,C组75．0％（18/24）,D组96．6％（112/116）,E组100．0％（27/27）,HBcAg阳性率与血清HBV DNA水平之间呈显著正相关（r=0．80,P＜0．01）。血清HBV DNA水平高低与HBeAg阳性率之间呈显著正相关（r=0．47,P＜0．01）。其中20例HBV DNA阴性者中（A组）,HBeAg阳性者5例（25％）,HBcAg阳性者11例（55％）；15例HBV DNA阴性且HBeAg阴性者中有7例HBcAg阳性,占46．7％。结论CHB患者肝组织HBcAg阳性能更可靠地反映肝细胞内HBV复制状态。检测肝组织内HBcAg对CHB患者疗效评价和对治疗反应性的预测更具有临床意义。     

拉米夫定治疗慢性乙型肝炎病人的长期疗效

通过多中心,承机,双盲,安慰剂对照的临床试验,研究拉米夫定（ｌａｍｉｖｕｄｉｎｅ）对慢性乙型肝炎（乙肝）病人的疗效和安全性。方法随机选择３２２例慢性乙肝病拉米夫定治疗（１００ｍｇ／ｄ）,１０７例病人服用安慰剂作对照,共治疗１２周,在１２周治疗结束后,拉米夫定组和安慰剂组病人均继续服用拉米夫定１００ｍｇ治疗至５２周。疗效评估包括临床症状和体征,肝功能和ＨＢＶ复制指标。结果治疗１２周,拉米夫定组ＨＢＶ     

不同结合臂长10-23 DNAzymes对乙型肝炎病毒S基因和C基因表达的抑制作用

目的探讨不同结合臂长10-23DNAzymes在2．2．15细胞内对乙型肝炎病毒S基因和C基因表达的抑制作用。方法设计并合成不同结合臂长的10-23 DNAzymes,能分别针对乙型肝炎病毒S基因和C基因开放阅读框A^157UG和A^1816UG。不同的10-23 DNAzymes分别转染2．2．15细胞,放射免疫分析法测定2．2．15细胞培养上清中HBsAg和HBeAg水平,实时荧光定量PCR法测定2．2．15细胞培养上清中HBVDNA水平。MTT法检测细胞毒性。结果不同结合臂长的10-23 DNAzymes在0．1—2．5μmol／L浓度范围内均能有效抑制HBsAg和HBeAg的表达,抑制效应可长达72h。在同一剂量相同转染时间的条件下,不同结合臂长的10．23 DNAzymes对HBsAg和HBeAg表达的抑制率呈以下关系：DrzBS-9〉DrzBS．8〉DrzBS-7;DrzBC-9〉DrzBC．8〉DrzBC-7。DrzBS-9和DrzBC-9在2．5~mol／L剂量条件下,转染48h后对HBsAg和HBeAg表达的抑制率可分别高达95％和92％。不同结合臂长的10-23DNAzymes对2．2．15细胞培养上清中HBVDNA水平并无明显影响。MTT细胞毒性检测表明,在0．1～2．5μmol／L浓度范围内未见10-23 DNAzymes对2．2．15细胞的毒性作用。结论不同结合臂长10-23 DNAzymes在2．2．15细胞内对乙型肝炎病毒s基因和c基因表达均有一定的抑制作用,DrzBS-9和DrzBC-9的抑制作用较强。     

正确认识乙型肝炎e抗原阴性慢性乙型肝炎

HBV感染的自然史中,HBeAg阴转往往代表炎症缓解。但在部分感染者中,感染初始可能即为HBeAg阴性,还有一部分慢性肝炎患者,在发生HBeAg阴转后炎症活动仍未停止。将HBeAg阴性且存在病毒血症的情形定义为HBeAg阴性的HBV感染。这种类型的感染在亚洲和欧洲南部占HBV感染者的比例为30%～80%,且有逐年增多的趋势,而在欧洲北部和美国只占10%～40%。近年来对这种类型的感     

经病理诊断的慢性乙型肝炎病毒携带者与慢性肝炎的临床分析

目的 比较病理学诊断为慢性HBV携带者与慢性肝炎患者的临床资料,为不同ALT水平的慢性HBV感染者的处理提供病理学依据.方法 对292例慢性HBV感染者进行肝活组织检查,按病理学诊断符合慢性HBV携带者标准(G0～G1且S0～S1)与慢性肝炎标准[G＞1和(或)S＞1]分为携带组和肝炎组,比较不同年龄分层及ALT水平分层与病理诊断的关系,同时比较其他可能与病理诊断相关的临床、生物化学及影像学指标,Logistic回归方程(后退法,极大似然法)进行多因素分析,确定病理学符合慢性HBV携带者诊断的独立影响因素.结果 292例患者中,病理诊断为慢性HBV携带者有140例,占47.9％;慢性肝炎152例,占52.1％.HBV携带组与慢性肝炎组在≤35岁与36～40岁、＞40岁比较,差异有统计学意义(x2=3.936,8.534;P=0.047,0.003); ALT水平在＜0.5×正常值上限(ULN)、(0.5～1.0)×ULN、(1.1～1.5)×ULN、(1.6～2.0)×ULN、＞2.0×ULN间比较差异有统计学意义(x2=55.314,P＜0.01),但ALT在(1.1～1.5)×ULN与＞2.0×ULN比较,差异无统计学意义(x2=3.810,P=0.051).多因素分析显示,病程、饮酒史、ALT分层、HBV DNA水平及超声检查肝表面是否光滑是病理学符合慢性HBV携带者诊断的独立影响因素(OR=0.995、0.224、0.516、1.308、0.270,P=0.005、0.007、0.000、0.025、0.001).结论 年龄35岁以上且ALT水平介于(1～2)×ULN的患者行肝活组织检查的临床意义更大.     

白细胞介素-10基因多态性与乙型肝炎病毒感染的关系

目的:探讨中国人白细胞介素-10基因启动子单核苷酸多态性与乙型肝炎病毒感染之后临床发展之间的关系.方法:分别采用聚合酶链反应-限制性片段长度多态性分析法(PCR-RFLP)和聚合酶链反应-序列特异性引物扩增法(PCR-SSP)检测478例慢性乙型肝炎患者,223例乙肝病毒携带者及267例自限性感染者基因组DNAIL-10基因启动子区域3个多态位点-592、-819、-1082的基因多态性,并进行相关性分析.结果:IL-10-1082A等位基因及AA基因型在慢性乙型肝炎患者组的频率明显高于自限性感染者组和乙肝病毒携带者组(A:χ2=37.72,P=0.000;χ2=45.23,P=0.000;AA:χ2=20.53,P=0.000;χ2=19.14,P=0.000).IL-10-819T等位基因及TT基因型在慢性乙型肝炎患者组的频率也高于自限性感染者组和乙肝病毒携带者组(T:χ2=10.5,P<0.001;χ2=17.38,P<0.001;TT:χ2=8.76,P=0.003;χ2=5.656,P=0.017).IL-10-592C/A等位基因频率和AA/CC/AC基因型在三组的分布没有统计学意义(P>0.05).结论:IL-10基因启动子多态性与乙肝病毒感染后临床发展过程可能相关.     

慢性乙型肝炎治疗的难点与热点

目前,对抗HBV治疗是慢性乙型肝炎治疗的最重要治疗手段已毋庸置疑,抗病毒治疗的概念、理念也已为广大临床所接受.经过10余年的慢性乙型肝炎治疗实践,对慢性乙型肝炎抗病毒治疗的适应证,药物选择和疗效的判断等均有了较为明确的认识.尽管对慢性乙型肝炎治疗的目标、适应证、方法、策略在各国指南中均已有清楚描述,但随着治疗人群增加和治疗时间延长,在临床实践中又出现新的难点和热点问题.     

Host susceptibility to persistent hepatitis B virus infection

Genetic epidemiology researches such as twin studies, family-clustering of hepatitis B virus (HBV) infection studies and ethnic difference studies have provided the evidence that host genetic factors play an important role in determining the outcome of HBV infection. The opening questions include which human genes are important in infection and how to find them. Though a number of studies have sought genetic associations between HBV infection/persistence and gene polymorphisms, the candidate gene-based approach is clearly inadequate to fully explain the genetic basis of the disease. With the advent of new genetic markers and automated genotyping, genetic mapping can be conducted extremely rapid. This approach has been successful in some infectious diseases. Linkage analysis can find host genes susceptible to HBV and is of great clinical importance.     

慢性乙型肝炎患者体内乙型肝炎病毒准种特点的初步研究

目的 探讨乙型肝炎病毒（HBV）准种在慢性乙型肝炎患者中的存在状态。方法 以已知中国株HBV基因序列为依据。设计特异性聚合酶链反应（PCR）引物,自3例慢性乙型肝炎患者体内扩增HBV全S基因片段,克隆人pGEMTeasy质粒,用限制性片段长度多态性（RFLP）法确定HBV的变异现象,DNA测序确定病毒的变异程度。结果 分别自3例患者血清中克隆出29、28和8个阳性克隆,以EcoRⅠ酶切患者1和2的RFLP结果提示各有5种不同的长度带型,PCR产物XhoI酶切RFLP结果表现为高度保守,测序结果发现HBV体内毒株DNA序列高度一致,同一患者两株全S区序列测序结果表明DNA序列的同源性大于97%。结论 慢性乙型肝炎患者体内有HBV准种共存,且呈现出一定的优势克隆现象。可能与患者预后有关。     

Genetic variation of occult hepatitis B virus infection

Occult hepatitis B virus infection(OBI), characterized as the persistence of hepatitis B virus(HBV) surface antigen(HBs Ag) seronegativity and low viral load in blood or liver, is a special form of HBV infection. OBI may be related mainly to mutations in the HBV genome, although the underlying mechanism of it remains to be clarified. Mutations especially within the immunodominant "α" determinant of S protein are "hot spots" that could contribute to the occurrence of OBI via affecting antigenicity and immunogenicity of HBs Ag or replication and secretion of virion. Clinical reports account for a large proportion of previous studies on OBI, while functional analyses, especially those based on full-length HBV genome, are rare.