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.     

HBV持续感染及其机制的研究进展

HBV属嗜肝DNA病毒科,可引起人类急性和慢性肝炎,甚至肝硬化、肝癌。目前的抗病毒药物因不能彻底清除肝细胞内HBV,故很难达到治愈的效果。近年来,HBV持续感染的机制受到广泛关注,主要涉及宿主与病毒两方面,从病毒方面展开,主要阐述了cccDNA、HBV颗粒和HBV自身组分维持HBV持续感染的相关研究进展。     

Relationship between interleukin-6 polymorphism and susceptibility to chronic hepatitis B virus infection

AIM:To identify the relationship between tag single nucleotide polymorphisms(tag SNPs) of interleukin-6(IL-6) gene and susceptibility to chronic hepatitis B virus(HBV) infection in a Han Chinese population.METHODS:We performed a case-control study of501 Chinese patients with chronic HBV infection and301 self-limiting HBV-infected individuals as controls.Genomic DNA was isolated from the whole blood of all subjects using phenol/chloroform with MaXtract highdensity tubes. Tag SNPs were identified using genotype data from the panel(Han Chinese in Beijing) of the phase II HapMap Project. Four tag SNPs in IL-6(rs17147230A/T,rs2066992G/T,rs2069837A/G and rs2069852A/G) were genotyped by the Multiplex Snapshot technique. The genotype and allele frequencies were calculated and analyzed.RESULTS:Five haplotypes were involved in the analysis,with frequencies higher than 0.03. One of the haplotypes,TTAA,was significantly different between the two groups. Overall haplotype P values were:ATAA,P = 0.605,OR(95%CI) = 1.056(0.860-1.297); TGAG,P = 0.385,OR(95%CI) = 1.179(0.813-1.709); TGGG,P = 0.549,OR(95%CI) = 1.087(0.827-1.429); TTAA,P = 0.004,OR(95%CI) = 0.655(0.491-0.873); TTAG,P = 0.266,OR(95%CI) = 1.272(0.832-1.944). However,the four SNPs showed no significant genotype/allele associations with susceptibility to chronic HBV infection. Overall allele P values were:rs17147230,P = 0.696,OR(95%CI) = 1.041(0.850-1.276); rs2066992,P = 0.460,OR(95%CI)= 1.090(0.868-1.369); rs2069837,P = 0.898,OR(95%CI) = 0.983(0.759-1.274); rs2069852,P = 0.165,OR(95%CI) = 0.859(0.693-1.064). Overall genotype P values were:rs17147230,P = 0.625; rs2066992,P= 0.500; rs2069837,P = 0.853; and rs2069852,P =0.380.CONCLUSION:The four tag SNPs of IL-6 gene may be associated with susceptibility to chronic HBV infection in the Han Chinese population.     

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.     

Chronic hepatitis B virus infection and rubella susceptibility in pregnant women

Summary. Increased rubella susceptibility has been shown in subjects from the Asian‐Pacific region where chronic hepatitis B virus (HBV) infection is endemic. This study was performed to explore the relationship between chronic HBV infection and rubella susceptibility in the obstetric population. We conducted a retrospective cohort study on 50556 pregnant women delivered in a university obstetric unit from January 1998 to June 2008. The incidence of rubella susceptibility according to maternal HBV carrier status was examined. HBV infection and rubella susceptibility were found in 5105 (10.1%) and 6102 (12.1%) women, respectively. Rubella susceptibility was more common in women with HBV (13.1%vs 12.0%, P = 0.017), even after adjusting for other confounding factors (odds ratio 1.11, 95% confidence interval 1.01–1.21). Advancing age was associated with progressively decreasing odds of rubella susceptibility, from 0.48 at age 20–24 years to 0.34 at age ≥40 years in women without HBV infection, but had no effect in women with hepatitis B. In conclusion, our study is the first to demonstrate an association between chronic HBV infection with rubella susceptibility. Further studies are warranted to confirm whether chronic HBV infection, especially that acquired by vertical transmission, may impair the immune response to rubella vaccine or natural infection throughout the reproductive age.     

Association of estrogen receptor alpha polymorphisms with susceptibility to chronic hepatitis B virus infection

Several studies have demonstrated that estrogen receptor alpha (ESR1) participates in the pathogenesis of persistent hepatitis B virus (HBV) infection. To examine whether polymorphisms at the ESR1 gene locus are associated with persistent HBV infection, we resequenced ESR1 genomic region for single nucleotide polymorphisms (SNPs) in 27 unrelated Chinese. Two haplotype-tagged SNPs (htSNP), T29C and A252966G, were selected for genotyping in 1,277 persistent HBV-infected cases, 748 spontaneously recovered controls, and 293 nuclear families using polymerase chain reaction (PCR)-restriction fragment length polymorphism (PCR-RFLP) analysis. We observed that the subjects bearing ESR1 29T/T genotype had an increased susceptibility to persistent HBV infection compared to those bearing at least one 29C allele (odds ratio 1.41; 95% CI, 1.17-1.71, P < .001). Consistent with the results of population-based association study, a significantly greater than expected transmission of the 29T allele (56.4%) from heterozygous parents to offspring with persistent HBV infection was observed (chi2 = 4.60, P = .033) using the transmission-disequilibrium test (TDT) in 293 nuclear families. Linkage disequilibrium (LD) mapping analysis indicated that the T29C polymorphism contained within a LD block located from promoter region to intron 3 of ESR1, suggesting that the strong association detected with T29C in ESR1 originated from ESR1 itself. In conclusion, our results suggest that the genetic variation at the ESR1 locus influences susceptibility to persistent HBV infection in a Chinese population.     

Immunoglobulin A antibody against hepatitis B core antigen in the acute and persistent infection with hepatitis B virus

Antibody to hepatitis B core antigen of immunoglobulin A class was determined in the serum of patients infected with hepatitis B virus by a sandwich-type solid-phase radioimmunoassay with monoclonal antibodies. The antibody, as defined by a sample to normal ratio greater than 2.1, was detected in all of 39 patients with acute hepatitis, with titers varying widely depending on the time of blood sampling. In persons with persistent infection, the antibody was detected in only 2 (4%) of 46 asymptomatic carriers of the virus, contrasting with the positivity in as many as 15 (41%) of 37 patients with chronic persistent hepatitis, in 45 (94%) of 48 patients with chronic active hepatitis, and in 40 (87%) of 46 patients with liver cirrhosis with or without hepatocellular carcinoma. The mean +/- SE titer of antibody in chronic persistent hepatitis (3.8 +/- 0.9) was significantly lower than those in chronic active hepatitis (13.8 +/- 3.2) and cirrhosis with or without carcinoma (25.6 +/- 6.1) (p less than 0.001). Based on the results obtained, the antibody may reflect hepatic injury in the persistent hepatitis B virus infection.     

IL-28B基因多态性与丙型肝炎易感性的关系

目的:探讨白介素-28B(interleukin-28B,IL-28B)单核苷酸多态性位点rs8099917与中国丙型肝炎易感性的关系.方法:采用TaqMan SNP基因分型的方法检测中国天津地区263名丙型肝炎患者和244名健康人IL-28B rs8099917基因型和等位基因分布情况,并统计分析rs8099917基因型和等位基因在2组中分布的差异.结果:在263名丙型肝炎患者中,TT基因型223人(84.8%),TG基因型39人(14.8%),GG基因型1人(0.4%).T等位基因频率为92.2%.244名健康对照者中,TT基因型222人(91.0%),TG21人(8.60%),GG1人(0.40%),T等位基因频率为95.3%.丙型肝炎患者和健康人群TG/GG基因型频率差异有统计学意义(OR=1.810,95%CI:1.042-3.145;P=0.033).丙型肝炎患者G等位基因频率也高于健康人(OR=1.709,95%CI:1.010-2.893;P=0.044).结论:中国人群IL-28B rs8099917基因多态性与丙型肝炎病毒(hepatitis C virus,HCV)感染易感性相关联.G为HCV感染的风险等位基因.     

Occult hepatitis B virus infection

The persistence of hepatitis B virus (HBV) genomes in HBV surface antigen (HBsAg) negative individuals is termed occult HBV infection. Occult HBV status is associated in some cases with mutant viruses undetectable by HBsAg assays, but more frequently it is due to a strong suppression of viral replication and gene expression. Occult HBV infection is an entity with world-wide diffusion, although the available data of prevalence in various categories of individuals are often contrasting because of the different sensitivity and specificity of the methods used for its detection in many studies. Occult HBV may impact in several different clinical contexts, including the transmission of the infection by blood transfusion or organ transplantation and its acute reactivation when an immunosuppressive status occurs. Moreover, much evidence suggests that it can favour the progression of liver fibrosis and above all the development of hepatocellular carcinoma.     

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

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

Many studies have shown that hepatitis B virus infection may also occur in hepatitis B surface antigen-negative patients. This occult infection has been identified both in patients with cryptogenic liver disease and in patients with hepatitis C virus-related chronic hepatitis, and much evidence suggests that it may be a risk factor of hepatocellular carcinoma development. However, several aspects of this occult infection remain unclear, such as its prevalence and the factor(s) involved in the lack of circulating hepatitis B surface antigen. Moreover, it is uncertain whether the occult hepatitis B virus infection may contribute to chronic liver damage, considering that it is usually associated with a suppressed viral replication. Evidence and hypotheses concerning this fascinating field of biomedical research are reviewed.     

Biological properties of interleukin-12 and its therapeutic use in persistent hepatitis B virus and hepatitis C virus infection

Summary. Interleukin (IL)-12 is a pleiotropic cytokine produced by antigen-presenting cells in response to diverse stimuli. IL-12 is a key molecule in the regulation of host's immune responses. In particular, IL-12 influences the balance between the T-helper cells type 1 (TH₁) and type 2 (TH₂); it modulates macrophage responses through the control of interferon-gamma synthesis by TH₁ cells; and, suppresses IgE class antibody production (has a suppressive effect on allergic reactions) and promotes a shift in the IgG subclasses. IL-12 enhances resistance to several infectious diseases, is a powerful antitumor agent in vivo , and acts as a vaccine adjuvant. The biological properties of IL-12 point to the potential therapeutic use in persistent hepatitis B virus and hepatitis C virus infection.     

影响HBV感染慢性化的宿主因素及其在乙型肝炎防治中的意义

乙型肝炎病毒(Hepatitis B Virus,HBV)可引起急性和慢性的肝脏感染,急性感染可致大约0.5％的患者死于爆发性肝炎,而慢性感染中,约25％的患者会变成不可治愈的肝癌,全世界死于由HBV感染所引起的肝癌人数每年超过一百万。急性和慢性肝病的不同结局很大程度上是由于机体对HBV感染的免疫反应所致,这种应答可以导致肝细胞的大范围的损伤,丧失必要的清除感染能力。目前还不知道为什么这种应答不能清除病毒而使许多人成为慢性病毒的携带者。因此,HBV研究的一个主要焦点是阐明有哪些宿主因素决定了HBV感染是急性的还是慢性的,这将有助于更好的治疗和降低肝细胞癌的发生概率。宿主和乙型肝炎病毒的许多因素决定了HBV感染的临床     

胎盘滋养层细胞的乙型肝炎病毒感染与宫内感染机制

目的：检测HBV对胎盘、胎肝和滋养层细胞的感染情况，探讨HBV的宫内感染机制。方法：研究对象包括20例孕妇胎盘组织、6例引产胎儿胎肝组织及体外培养的胎盘滋养层细胞。ELISA法检测孕妇外周血、胎儿脐血和6个月婴儿外周血HBV标志物；荧光定量PCR法检测血清和滋养层细胞中的HBV DNA；免疫组织化学法和免疫荧光法检测胎盘、胎肝组织及滋养层细胞中HBV标志物的表达；末端脱氧核糖核酸转移酶介导的缺口标记法（TUNEL）检测胎盘和滋养层细胞凋亡情况。结果：孕妇血清HBV DNA水平与胎儿脐血HBV DNA水平相关，脐血HBV DNA阳性者其母血HBV DNA〉1.0×10^7拷贝／mL；6例胎盘组织和3例引产胎儿胎肝组织中可见HBsAg免疫组织化学染色阳性细胞，其中1例胎肝组织中发现HBcAg阳性细胞；体外培养滋养层细胞与HBV DNA阳性血清共孵育后，可检测到HBsAg的表达，亦可检测到HBV DNA。体内和体外实验均检测到HBV感染后滋养层细胞凋亡呈增加趋势，且胎盘细胞的凋亡与脐血HBV DNA水平相关。体外实验结果显示，随感染时间的延长，滋养层细胞凋亡呈增加趋势。6个月后，12例新生儿有1例血清HBsAg、HBeAg和抗-HBc阳性，6例抗-HBs阳性。结论：HBV宫内感染的机制可能是通过HBV感染胎盘屏障而使胎儿发生HBV宫内感染。HBV在胎儿组织器官内的定位和复制可能是新生儿发生慢性HBV感染的重要因素。滋养层细胞凋亡可能是胎盘屏障阻断HBV宫内传播的一种保护性机制。     

白细胞介素-12B+1188位点基因多态性与乙型肝炎病毒宫内感染的关系

目的分析IL-12B基因3’非翻译区（UTR）＋1188（A／C）位点单核苷酸多态性（SNP）与HBV宫内感染易感性的关系，探讨高危儿童发生宫内HBV感染的易感因素。方法母亲为HBV携带[HBsAg和（或）HBeAg阳性，或HBVDNA阳性]所生新生儿，出生后按程序进行主、被动联合免疫，出生时外周静脉血HBsAg和（或）HBVDNA阳性，并持续6个月以上者为宫内感染组，共70例；出生时及后期随访中未出现过HBsAg和（或）HBVDNA阳性，1岁时抗-HBs达保护滴度（〉10mU／L）者为宫内未感染组，71例；另取健康儿童外周血共40份作为对照。提取外周血基因组DNA，PCR扩增目的片段后进行测序，检测IL-12B基因3’UTR＋1188（A／c）位点SNP。结果宫内感染组IL-12B基因＋1188位点AA、AC、CC基因型分布频率分别为25．7％、44．3％和30．0％，宫内未感染组三种基因型分布频率为36．6％、47．9％和15．5％，正常对照组三种基因型的分布频率分别为48．8％、39．0％和12．2％。宫内感染组与宫内未感染组间CC基因型和非CC基因型之间频率分布差异有统计学意义（X^2=17．078。P〈0．01，ORex=2．338，95％CI：1．028～5．035）；三组等位基因频率分别为A47．8％、60．7％和67．8％；C52．2％、39．3％和32．2％，宫内感染组与宫内未感染组等位基因频率比较，无异有统计学意义（X^2=4．586，P=0．032；ORA=0．597，95％CI：0．372～0．959；ORc=1．673，95％CI：1．043～2．684）。结论IL-12B＋1188位点A／C多态性CC基因型及C等位基因携带高危儿童可能易发生HBV宫内感染，而对携带HBV母亲所生的高危儿A等位基因可能对发生HBV宫内感染有一定的保护作用。     

Latent hepatitis B virus infection with full-length viral genome in a patient serologically immune to hepatitis B virus infection

The presence, state, physical structure and cellular localization of hepatitis B virus (HBV) DNA were investigated in a patient with hepatitis B surface antigen (HBsAg)-negative chronic liver disease. HBV serology was positive for antibodies to hepatitis B core antigen (anti-HBc), to hepatitis B e antigen (anti-HBe) and to HBsAg (anti-HBs); no HBV DNA was detectable in serum. Southern blot analyses of DNA extracted from the liver demonstrated free monomeric HBV DNA as two distinct species: a predominant species of fully double-stranded relaxed circular molecules and a minor species of linear molecules of 3.2 kilobase pairs (kbp) length. Restriction enzyme analyses identified the HBV genome as HBsAg subtype adw2. Cell fractionation studies further revealed that the free viral DNA species were localized exclusively in liver cell nuclei. These findings in a patient serologically immune to HBV infection demonstrate that in hepatocytes HBV can establish a latent infection, characterized by the extrachromosomal presence of a full-length viral genome without production of infectious virus or synthesis of viral antigens.