Occult hepatitis B virus and hepatocellular carcinoma

Occult hepatitis B virus (HBV) infection (OBI) is a challenging pathobiological and clinical issue that has been widely debated for several decades. By definition, OBI is characterized by the persistence of HBV DNA in the liver tissue (and in some cases also in the serum) in the absence of circulating HBV surface antigen (HBsAg). Many epidemiological and molecular studies have indicated that OBI is an important risk factor for hepatocellular carcinoma (HCC) development. OBI may exert direct pro-oncogenic effects through the activation of the same oncogenic mechanisms that are activated in the course of an HBsAg-positive infection. Indeed, in OBI as in HBV-positive infection, HBV DNA can persist in the hepatocytes both integrated into the host genome as well as free episome, and may maintain the capacity to produce proteins-mainly X protein and truncated preS-S protein - provided with potential transforming properties. Furthermore, OBI may indirectly favor HCC development. It has been shown that the persistence of very low viral replicative activity during OBI may induce mild liver necro-inflammation continuing for life, and substantial clinical evidence indicates that OBI can accelerate the progression of liver disease towards cirrhosis that is considered the most important risk factor for HCC development.     

隐匿性乙型肝炎病毒感染

大量研究通过对肝组织和血清乙型肝炎病毒（HBV）DNA或转录体的检测，证实隐匿性HBV感染是所谓“隐源性肝炎”及其它慢性肝病的常见病因。现就其发生率、形成机制、临床意义、诊断、治疗等方面作一综述。     

Occult hepatitis B virus infection among Mexican human immunodeficiency virus-1-infected patients

AIM: To determine the frequency of occult hepatitis B infection (OHBI) in a group of human immunodeficiency virus (HIV)-1+/ hepatitis B surface antigen negative (HBsAg)- patients from Mexico.METHODS: We investigated the presence of OHBI in 49 HIV-1+/HBsAg- patients. Hepatitis B virus (HBV) DNA was analyzed using nested PCR to amplify the Core (C) region and by real-time PCR to amplify a region of the S and X genes. The possible associations between the variables and OHBI were investigated using Pearson’s χ² and/or Fisher’s exact test.RESULTS: We found that the frequency of OHBI was 49% among the group of 49 HIV-1+/HBsAg- patients studied. The presence of OHBI was significantly associated with the HIV-1 RNA viral load [odds ratio (OR) = 8.75; P = 0.001; 95%CI: 2.26-33.79] and with HIV-antiretroviral treatment with drugs that interfere with HBV replication (lamivudine, tenofovir or emtricitabine) (OR = 0.25; P = 0.05; 95%CI: 0.08-1.05).CONCLUSION: The OHBI frequency is high among 49 Mexican HIV-1+/HBsAg- patients and it was more frequent in patients with detectable HIV RNA, and less frequent in patients who are undergoing HIV-ARV treatment with drugs active against HBV.     

Occult hepatitis C virus infection is more common than hepatitis B infection in maintenance hemodialysis patients

Patients of end stage renal disease on maintenance hemodialysis were enrolled to study the prevalence of occult and dual hepatitis B virus （HBV） and hepatitis C virus （HCV） infection and non-occult hepatitis B and C virus infection. One hundred and two patients were enrolled. Thirty patients had HCV infection, three of them were positive in anti-HCV. So, 27 （90%） of HCV-positive patients had occult HCV infection. Eleven （11%） patients had HBV infection. Five patients were positive in anti-HBc or HBV-DNA, but negative in HBsAg （occult HBV infection）. Three （3%） patients had dual HBV and HCV infection. None of the patients showed changes in viral markers during the follow-up of 8 mo on average （1-12 mo）.     

An overview of occult hepatitis B virus infection

Occult hepatitis B virus (HBV) infection (OBI), alternatively defined as occult hepatitis B (OHB), is a challenging clinical entity. It is recognized by two main characteristics: absence of HBsAg, and low viral replication. The previous two decades have witnessed a remarkable progress in our understanding of OBI and its clinical implications. Appropriate diagnostic techniques must be adopted. Sensitive HBV DNA amplification assay is the gold standard assay for detection of OBI. Viral as well as host factors...     

Diagnostic strategy for occult hepatitis B virus infection

In 2008,the European Association for the study of the liver(EASL) defined occult hepatitis B virus infection (OBI) as thepresence of hepatitis B virus(HBV) DNA in the liver(with detectable or undetectable HBV DNA in the serum) of individuals testing hepatitis B surface antigen(HBsAg) negative by currently available assays.Several aspects of occult HBV infection are still poorly understood,including the definition itself and a standardized approach for laboratory-based detection,which is the purpose of this ...     

Occult hepatitis B virus infection in Egypt

The emerging evidence of the potentially clinical importance of occult hepatitis B virus (HBV) infection (OBI) increases the interest in this topic. OBI may impact in several clinical contexts, which include the possible transmission of the infection, the contribution to liver disease progression, the development of hepatocellular carcinoma, and the risk of reactivation. There are several articles that have published on OBI in Egyptian populations. A review of MEDLINE database was undertaken for relevant articles to clarify the epidemiology of OBI in Egypt. HBV genotype D is the only detectable genotype among Egyptian OBI patients. Higher rates of OBI reported among Egyptian chronic HCV, hemodialysis, children with malignant disorders, and cryptogenic liver disease patients. There is an evidence of OBI reactivation after treatment with chemotherapy. The available data suggested that screening for OBI must be a routine practice in these groups of patients. Further studies needed for better understand of the epidemiology of OBI among Egyptian young generations after the era of hepatitis B vaccination.     

Occult infection related hepatitis B surface antigen variants showing lowered secretion capacity

AIM:To elucidate the molecular mechanisms underlying hepatitis B virus(HBV)occult infection of genotype C.METHODS:A total of 10 types of hepatitis B surface antigen(HBs Ag)variants from a Korean occult cohort were used.After a complete HBV genome plasmid mutated such that it does not express HBs Ag and plasmid encoding,each HBs Ag variant was transiently co-transfected into Hu H-7 cells.The secretion capacity and intracellular expression of the HBV virions and HBs Ags in their respective variants were analyzed using real-time quantitative polymerase chain reaction assays and commercial HBs Ag enzyme-linked immunosorbent assays,respectively.RESULTS:All variants exhibited lower levels of HBs Ag secretion into the medium compared with the wild type.In particular,in eight of the ten variants,very low levels of HBs Ag secretion that were similar to the negative control were detected.In contrast,most variants(9/10)exhibited normal virion secretion capacities comparable with,or even higher than,the wild type.This provided new insight into the intrinsic nature of occult HBV infection,which leads to HBs Ag sero-negativeness but has horizontal infectivity.Furthermore,most variants generated higher reactive oxidative species production than the wild type.This finding provides potential links between occult HBV infection and liver disease progression.CONCLUSION:The presently obtained data indicate that deficiency in the secretion capacity of HBs Ag variants may have a pivotal function in the occult infections of HBV genotype C.     

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.     

慢性乙型肝炎肝组织内HBsAg、HBcAg的表达及临床研究进展

一直以来临床将血清乙型肝炎e抗原(HBeAg)、乙肝病毒DNA(HBV DNA)阳性作为乙肝病毒复制的标志,随着肝穿活检及抗病毒治疗的研究进展,肝活检组织中乙肝表面抗原(HBsAg)和乙肝核心抗原(HBcAg)的表达模式与血清乙型肝炎病毒(HBV)DNA定量、肝组织炎症活动度分级及纤维化分期之间关系的临床研究日益增多,本文就HBsAg和HBcAg在肝组织的表达模式及临床研究进展综述如下.     

Occult hepatitis B in blood donors in Indonesia: altered antigenicity of the hepatitis B virus surface protein

Background and aims  

Occult hepatitis B virus infection (OBI) poses a challenge to the safety of blood donation. The prevalence of OBI is not well documented in Indonesia, although this information in such an endemic country is needed. This study was aimed to evaluate the prevalence of occult hepatitis B in blood donors from two cities of Indonesia, and to study the genetic variation and its effect on the predicted antigenicity of HBsAg.     

隐匿性乙型肝炎:免疫组织化学和S基因序列分析

目的　了解不明原因慢性肝病中隐匿性乙型肝炎所占比例 ,隐匿性乙型肝炎的发病机制及临床、病理特点。方法　给予 2 0例不明原因慢性肝病患者肝穿刺病理检查 ,应用免疫组织化学方法检测肝组织内的乙型肝炎病毒表面抗原 (HBsAg)、核心抗原 (HBcAg) ,丙型肝炎病毒NS3、NS4抗原。采用荧光定量PCR方法对血清HBVDNA进行定量 ,用套式PCR方法扩增HBVS基因 ,对PCR产物进行直接测序 ,比较S基因的核苷酸和推导出的氨基酸序列的差异。结果　 5例患者经肝脏病理检查表现为慢性炎症 ,3例在肝组织内HBsAg、HBcAg同时阳性 ,2例仅HBcAg阳性。S基因的氨基酸序列分析显示 ,1例患者S基因的 74位密码子发生终止变异 ,另 1例在HBsAg的“a”决定簇内有 2个氨基酸发生变异 (T13 1N ,M 13 3S) ,其他 3例患者HBsAg的“a”决定簇内未发现变异。 结论　在我国隐匿性乙型肝炎是不明原因肝病的主要原因之一 ,低水平的血清HBVDNA可以引起慢性肝炎。部分隐匿性乙型肝炎HBsAg阴性的原因是S基因变异引起的 ,而有些患者则可能因为血清HBsAg水平过低 ,导致HBsAg检测阴性。     

Occult Hepatitis B Virus Infection in Hemodialysis Patients: A Concept for Consideration

Hemodialysis patients potentially have an increased risk of infection with parenterally transmitted viral agents due to an impaired host immune response and multiple transfusion requirements. Viral hepatitis is considered as a problem for hemodialysis patients because 1.9% of all deaths among this population are related to the consequence of viral hepatitis. Hepatitis B virus (HBV) is one of the most important causes of transmitted infections by the parenteral route in hemodialysis patients. Occult HBV infection is characterized by presence of HBV infection without detectable hepatitis B surface antigen (HBsAg), which harbors potential risk of HBV transmission through hemodialysis. There are conflicting reports on the prevalence of occult HBV infection (OBI) in hemodialysis patients. Considering the importance of occult HBV infection in hemodialysis patients and the growing evidence on this subject, the purpose of this review is to provide comprehensive information on OBI prevalence in hemodialysis patients and highlight the most important points in this issue.     

Spatial and chronological differences in hepatitis B virus genotypes from patients with acute hepatitis B in Japan

Genotypes of hepatitis B virus (HBV) were determined in 485 patients with acute hepatitis B from all over Japan. They were A in 92 (19%), Ba in 26 (5%), Bj in 32 (7%), C in 330 (68%) and D in 5 (1%). Sexual contacts were the main route of transmission in them. Overall, HBV persisted in only 5 of the 464 (1%) followed patients. Genotypes C accounted for more than 68% in northern as well as southern areas, contrasting with genotype A accounting for 34% in and around the Metropolitan areas. During 24 years from 1982 to 2005, genotype A increased from 5% to 33%, while genotype B gradually decreased from 26% to 8%. Fulminant hepatitis was significantly more frequent in infection with genotype Bj (41%) than those with the other genotypes (p < 0.01). The core-promoter double mutation (T1762/A1764) and precore stop-codon mutation (A1896) were more frequent in patients with fulminant than acute self-limited hepatitis (57% versus 15% and 58% versus 10%, respectively, p < 0.01 for both). In conclusion, genotype A distributes unevenly over Japan, prevails in younger patients through sexual transmission and has increased with years. Furthermore, fulminant outcome was more frequent in patients with genotype Bj than those with the other genotypes.     

Occult hepatitis B virus infection

Occult hepatitis B virus(HBV)infection(OBI)refers to the presence of HBV DNA in the absence of detectable hepatitis B surface antigen.Since OBI was first described in the late 1970s,there has been increasing interest in this topic.The prevalence of OBI varies according to the different endemicity of HBV infection,cohort characteristics,and sensitivity and specificity of the methods used for detection.Although the exact mechanism of OBI has not been proved,intrahepatic persistence of viral covalently closed circular DNA under the host’s strong immune suppression of HBV replication and gene expression seems to be a cause.OBI has important clinical significance in several conditions.First,OBI can be transmitted through transfusion,organ transplantation including orthotopic liver transplantation,or hemodialysis.Donor screening before blood transfusion,prophylaxis for high-risk organ transplantation recipients,and dialysis-specific infection-control programs should be considered to reduce the risk of transmission.Second,OBI may reactivate and cause acute hepatitis in immunocompromised patients or those receiving chemotherapy.Close HBV DNA monitoring and timely antiviral treatment canprevent HBV reactivation and consequent clinical deterioration.Third,OBI may contribute to the progression of hepatic fibrosis in patients with chronic liver disease including hepatitis C.Finally,OBI seems to be a risk factor for hepatocellular carcinoma by its direct protooncogenic effect and by indirectly causing persistent hepatic inflammation and fibrosis.However,this needs further investigation.We review published reports in the literature to gain an overview of the status of OBI and emphasize the clinical importance of OBI.     

Occult hepatitis B virus infection: a complex entity with relevant clinical implications

Occult hepatitis B virus(HBV) infection is a world-wide entity,following the geographical distribution of detectable hepatitis B.This entity is defined as the persistence of viral genomes in the liver tissue and in some instances also in the serum,associated to negative HBV surface antigen serology.The molecular basis of the occult infection is related to the life cycle of HBV,which produces a covalently closed circular DNA that persists in the cell nuclei as an episome,and serves as a template for gene tra...     

隐匿性乙型肝炎病毒感染者血清表面抗体性质鉴定

目的 了解隐匿性HBV感染者抗-HBs的特性及其与HBsAg的结合能力.方法 对2例抗-HBs阳性的隐匿性HBV感染者进行长期随访,使用多种试剂盒对患者血清进行多次HBsAg检测,利用不同血清型HBsAg对患者血清进行中和反应,了解血清中抗体亚型情况.PCR扩增S基因构建真核表达质粒,分析S基因变异情况,并将质粒转染HepG2细胞,取培养上清液及转染细胞分别混合进行HBsAg检测.使用患者血清及抗-HBs阳性血清(对照组)对部分HBsAg阳性克隆上清液进行中和反应.不同组间数据比较采用t检验.结果 多种试剂盒进行的多次检测结果均表明患者血清HBsAg为阴性;HBsAg的3种不同血清型(adr、adw、ay)均能够中和患者血清中大部分抗-HBs(82.1%～100.0%).S基因序列分析表明核苷酸同源性和氨基酸同源性分别为95.13%～97.79%和92.04%～95.58%;培养上清液和转染细胞裂解液中HBsAg定量分别为对照组的48.1%和59.3%,上清液/细胞裂解液比值分别为0.85和0.38.中和试验结果显示转染上清液中HBsAg定量较混合前有所降低,但是仍然可以检测到,而对照组检测不到HBsAg,差异均有统计学意义(F值分别为353.6和645.2,P值均<0.01).结论 抗-HBs阳性隐匿性HBV感染者体内HBsAg的抗原性及分泌能力有所下降,抗HBs主要针对不同血清型HBsAg的共同表位,但可能与疫苗注射产生的抗-HBs有所不同.

Abstract：

Objective To investigate the properties of HBsAb in occult hepatitis B virus infection and its affinity to different serotypes of hepatitis B virus surface antigen (HBsAg). Methods Long-term follow-up was conducted in 2 HBsAb positive patients with occult hepatitis B virus infection. HBsAg was detected using multiple diagnostic kits and the HBsAb subtype was determined by performing neutralization experiments with different serotypes of HBsAg. The viral S gene was PCR-amplified and mutation analysis was conducted. Plasmids expressing HBsAgs were constructed by inserting these PCR products into an eukaryotic expression vector and were then transfected into HepG2 cells. The cell culture supernatant and cellular extracts were detected for HBsAg respectively. Neutralization experiments were carried out in the cell culture supernatant from HBsAg plasmids transfected HepG2 cells and serum samples from these patients and others who had been confirmed to be positive for HBsAb. Results Multiple tests using various diagnostic kits showed that the 2 patients were negative for HBsAg and the three different serotypes of HBsAg (adr, adw, ay) could neutralize 82.1%-100% of HBsAb existed in the 2 patients. Sequence analysis of S gene cloned from these patients revealed that the homology to reference strain were 95.13%-97.79% and 92.04%-95.58% respectively at the nucleotide and amino acid levels. Quantitation of HBsAg showed that the expression levels of HBsAg from the two patients were 41.1% and 22.6% respectively of that of control HBsAg in cell culture supernatant and 48.1% and 59.3% respectively in cellular extract, and the supernatant/cell lysate ratios were 0.85 and 0.38 respectively. In neutralization experiments, HBsAg could be totally absorbed by control serum, whereas could only be partially neutralized by HBsAbs from the two patients (F = 353.6 and 645.2, P < 0.01). Conclusion Both the antigenicity and the ability of HBsAg secreted outside of the cells are decresed in these HBsAb-positive patients with occult HBV infection. The HBsAbs are mainly specific for common epitopes among different serotypes of HBsAg and are probably different as compared with those produced by vaccine inoculation.     

乙型肝炎病毒基因型对拉米夫定治疗早期血清乙型肝炎表面抗原水平变化的影响

目的了解血清乙型肝炎表面抗原（HBsAg）水平在拉米夫定治疗早期的变化特点及乙型肝炎病毒（HBV）基因型在其中的作用。方法乙型肝炎e抗原（HBeAg）阳性且拉米夫定为初始抗病毒治疗的慢性乙型肝炎患者87例,雅培HBsAg Architect方法定量检测治疗基线和第12周血清HBsAg水平;采用聚合酶链反应联合限制性片段长度多态性分析的方法确定HBV基因型。结果所有患者治疗第12周血清HBV DNA水平下降（中位数4．31log10拷贝／ml,P〈0．001）。总的血清HBsAg下降至基线的57．99％（P〈0．001）,但主要发生在HBV基因B型患者（43例,P〈0．001）,在HBV基因C型患者变化不明显（43例,P=0．378）。血清HBsAg和HBV DNA变化（基线和12周）之间的正相关关系仅存在于基因B型（Rs=0．577,P〈0．001）,而在C型患者中不明显（Rs=0．068,P=0．686）。基线HBsAg水平低（比数比值为0．387,95％可信区间为0．188～0．794,P=0．010）和HBV基因C型感染（比数比值为4．083,95％可信区间为1．362～12．236,P=0．012）是导致32．2％（29例）患者血清HBsAg水平未下降的主要因素。结论在拉米夫定治疗HBeAg阳性慢性乙型肝炎的早期,超过30％的患者血清HBsAg水平并没有随着HBV DNA复制水平下降而下降,HBV基因C型感染和基线HBsAg水平低是其主要因素。     

Identification of mutations in the S gene of hepatitis B virus in HIV positive Mexican patients with occult hepatitis B virus infection

Introduction and aimOccult hepatitis B virus infection (OBI) is characterized by the presence of replication-competent hepatitis B virus (HBV) DNA in the liver and/or serum of patients with undetectable levels of the HBV surface antigen (HBsAg). Due to the shared infection routes HIV positive patients are at higher risk of developing OBI, thus, the aim of this study was to determine the frequency of OBI in Mexican HIV-infected patients and to identify mutations in the HBV S gene that could be associated to the development of OBI.Materials and methodsPlasma samples from 50 HIV-infected patients with undetectable levels of the HBsAg were obtained and analyzed. The Core, PreS and S genes were amplified by nested PCR and sequenced by the Sanger method. To analyze HBV diversity in the OBI-positive patients, ten sequences of 762 bp from the HBV S gene were selected, cloned, and subsequently sequenced for mutational analyses.ResultsOBI infection was found with a frequency of 36% (18/50). All the HBV sequences corresponded to the H genotype. The most common mutations were: C19Y, Q129H, E164D, and I195M, with a frequency of 44%, 36%, 39% and 48% respectively.ConclusionsIn this study, we report the presence of OBI in a cohort of Mexican HIV-infected patients with an overall prevalence of 36%. Mutational analyses revealed that four non-silent mutations were frequent in different regions of the HBsAg gene, suggesting that they might be associated to the development of OBI in this population, nevertheless, further studies are required to determine their role in the pathogenesis of OBI.