Prevalence of hepatitis B virus precore stop codon mutations in chronically infected children

AIM: To find out whether there is a significant difference in the prevalence of the precore stop codon mutation between HBeAg positive and anti-HBe positive children. METHODS: We investigated a large pediatric population of 155 European children (mean age 10.9 years) with chronic hepatitis B by PCR and direct sequencing. Ninety were HBeAg positive and 65 had seroconversion to anti-HBe. Additionally genotyping was performed. RESULTS: Seventy-four (48%) of the sequenced HBV strains were attributed to genotype D and 81 (52%) to genotype A. In the group of 90 HBeAg positive patients, 2 (2.2%) 1896-G-to-A transitions leading to precore stop codon mutation were found, and in the group of 65 anti-HBe positive children, 5 (7.7%) were identified harbouring HBeAg-minus mutants. The difference was not statistically significant (P=0.13). CONCLUSIONS: HBeAg minus variants as predominant viral HB strains play a minor role in the course of chronic hepatitis B in European children.     

The loss of HBeAg without precore mutation results in lower HBV DNA levels and ALT levels in chronic hepatitis?B virus infection

Background  The aim of this study was to investigate the correlation between precore (PC)/basal core promoter (BCP) mutations and the viral loads or activity of hepatitis in patients with chronic hepatitis B virus (HBV) infection. Methods  HBV genotypes, PC mutations, BCP mutations, HBV DNA levels, and serological markers of HBV were analyzed in all the patients with chronic HBV infection seen in Fujita Health University Hospital from June 2004 to November 2008 (n = 215). Results  HBV genotype was C in 169 patients, B in 16, A in 3, F in 1, and unclassifiable in 5. Among the patients with genotype C, the prevalence of PC wild type was significantly lower in hepatitis B envelope antigen (HBeAg)(−) patients than in HBeAg(+) patients (9.5% versus 49.0%, P < 0.0001). Among HBeAg(−) patients, the patients with PC wild type had significantly lower serum viral loads and alanine aminotransferase (ALT) levels compared with those with PC mutant (P < 0.001). Among HBeAg(−) patients, the patients with genotype B had lower serum viral loads compared with those with genotype C (3.6 ± 0.9 versus 4.6 ± 1.6, P < 0.05), and the prevalence of BCP wild type was significantly higher in those with genotype B than in those with genotype C (58.3% versus 10.8%, P < 0.05). Conclusions  Among HBeAg(−) patients with genotype C, the patients with PC wild type had significantly lower viral loads and ALT levels than those with PC mutant. This suggests that the patients with PC wild type may have better prognosis than those with PC mutant among HBeAg(−) patients with genotype C.     

The effect of the G1888A mutation of subgenotype A1 of hepatitis B virus on the translation of the core protein

A distinctive characteristic of subgenotype A1 of hepatitis B virus is G1888A in the precore region. This transition introduces an out-of-frame AUG, creating an overlapping upstream open reading frame (uORF), terminating five nucleotides downstream from the core AUG. This uORF can potentially be translated into a seven amino acid peptide. In addition to stabilizing the encapsidation signal by forming a base pair with T1871, this mutation may affect translation of the core protein. The aim of this study was to use reporter constructs to determine whether G1888A had any modulating effect on core protein translation. The complete core gene with part of the precore of subgenotype A1 was cloned into the amino terminal of a green fluorescent protein (GFP) plasmid. Core/GFP fusion protein expression was measured using flow cytometry following transfection of Huh 7 cells. The introduction of uORF resulted in an 18.75% reduction of core gene expression. When the suboptimal Kozak sequence of the 1888 AUG was replaced with an optimal one, this reduction was enhanced (64.84%). By increasing the distance between the stop of the overlapping uORF and the core AUG, by a minimum of 15 nucleotides, core/GFP expression was almost doubled, indicating that stalling of ribosomes at the stop of the uORF may be interfering with initiation at the core AUG through steric hindrance. Our findings indicate that the G1888A mutation, may interfere with initiation at the downstream 1901 core AUG, decreasing core protein translation. This decrease may account for the relatively low viral loads seen in individuals infected with subgenotype A1.     

肝脏疾病与HBV前C区1896位点突变的研究

目的 :分析乙型肝炎病毒 ( HBV)前 C区 1 896位点突变与慢性乙型肝炎 ( CAH)、活动性肝硬化( ALH)和肝细胞肿瘤 ( HCC)的关系。方法 :根据 HBV前 C区 DNA序列 ,采用聚合酶链式反应 ( PCR)分析 HBV第 1 896位核苷酸 G→ A( A1 896)的突变。结果 :通过对三种肝脏疾病患者血清的检测 ,发现CAH、ALH和 HCC患者血清中均存在 HBV突变株 ,其阳性率分别为 47.2 2 % ( 1 7/36)、53.33% ( 9/1 5)和 2 6.0 8% ( 6/2 3)。结论 :CAH和 ALH患者检出率较高 ,而 HCC患者检出率较低 ,说明 HBV突变与HBV在人体持续感染及感染后病情恶化有关 ;HBV突变是引起 HCC的原因之一 ,但并非主要因素     

重型病毒性肝炎432例病原学分析

目的 探讨病毒性肝炎病原学与慢性肝炎重症化及其预后的关系。方法 对432例重型病毒性肝炎的病原学资料进行回顾性分析。结果 在引起重肝的肝炎病毒中以HBV单一或重叠感染率最高(414/432,95.8％),未发现单一HAV、HDV和HGV感染引起者。10例(2.31％)未能确定病原。乙型慢性重型肝炎的HBV前C区变异率为59.8％(55/92),显著高于乙型急性或亚急性重型肝炎0％(P<0.05和P<0.01)。HBV重叠HEV感染者病死率为73.4％(69/94),HEV重叠其他肝炎病毒感染者的病死率为68.6％(72/105),均比单一HBV或单一HEV感染者高(P<0.01和P<0.05)。结论 HBV感染仍是广东地区重型肝炎的主要病因。乙型慢性重型肝炎多由HBV前C区变异所致。HBV与HEV重叠感染可加重病情,病死率高。     

慢性乙型肝炎患者HBe系统与HBV DNA前C区基因突变的分析

目的研究HBV DNA前C区基因突变与HBe系统的关系.方法对88例慢性乙型肝炎患者进行HBVDNA基因检测(PCR法)、分子克隆及序列分析.结果88例患者中,血清HBV DNA阴性22例,阳性66例.从阳性患者中检出野生株感染22例,占33.3%;突变株感染44例,占66.7%.44例突变株感染者中38例属1898位点及/或1901位点突变,占86.4%;其他形式突变6例,占13.6%;66例血清HBV DNA阳性中,CHB 49例,LC 17例,突变株感染检出率分别为69.3%、58.8%,两者经统计学处理无显著性差异(P＞0.05).在HBe系统中,HBV DNA阳性患者属HBeAg(+)者44例,其中突变株检出率为75.0%(33/44),属抗HBe(+)者20例,其中突变株检出率为50.0%(10/20),两者经统计学处理有显著性差异(P＜0.05).结论①在HBe系统中,HBeAg(+)患者的突变株检出率高于抗HBe(+)患者(P＜0.05),提示其位点突变株在HBeAg(+)中占优势,与以往文献报道中关于1896位点突变株主要存在于抗-HBe(+)患者中的结论不尽相同.因此,应考虑HBeAg(+)患者也存在病毒突变的可能.②HBV慢性感染过程中,CHB患者与LC患者的突变株感染检出率无显著性差异(P＞0.05),表明在1898及/或1901位点的突变株感染与肝脏损害程度无平行关系.     

HBeAg negative variants and their role in the natural history of chronic hepatitis B virus infection

Molecular virology methods including polymerase chain reaction,cloning and sequencing have revolutionised our understanding of viral genome variation.In the case of hepatitis B virus(HBV),sequencing studies have identified a number of virus variants normally found during the natural course of chronic infection.The appearance of the precore stop codon(with G-for-A substitution at position 1896)and basal core promoter(BCP)(with A-for-T and G-for-A,at positions 1762 and 1764,respectively)variants which reduce or abrogate hepatitis B e antigen(HBeAg)production,heralds the initiation of the seroconversion phase from HBeAg to antiHBe positivity.The gradual removal of the tolerogenic effect of HBeAg leads to the awakening of the immune response(immune clearance phase).Most patients after HBeAg seroconversion become"inactive HBsAg carriers".However during the course of infection precore and/or BCP variants may emerge and be selected leading to HBeAg negative chronic hepatitis B(CHB)with high viremia levels(reactivation phase).The prevalence of HBeAg negative CHB has been increasing over the last few decades and has become the commonest type of HBV infection in many countries of the world.This probably reflects the aging of existing HBV carriers and the effective prevention measures restricting new HBV infections.Frequent acute exacerbations accompanied by high viral replication,elevated alanine aminotransferase levels and histological activity are a common feature of HBeAg negative CHB leading to cirrhosis much faster than in HBeAg positive CHB patients.     

"大三阳"、"小三阳"患者血清中HBVC基因启动子和前C基因变异模式的研究

目的　研究“大三阳”、“小三阳”患者血清中HBVC基因启动子和前C基因变异模式。方法　通过基因序列分析检测 75例“大三阳”患者和 5 2例“小三阳”患者血清中HBVC基因启动子和前C基因序列。结果　 (1)“大三阳”患者血清中HBVnt1719、nt172 6、nt172 6 - 1730、nt1799和联变 (176 2 176 4 1896 )的变异率与“小三阳”患者间差别有显著性意义 (P <0 0 5 )。 (2 )“大三阳”患者血清中HBVnt1896终止变异率与“小三阳”患者间差别有非常显著性意义 (P <0 0 1)。 3 “大三阳”患者中 ,eAg高组nt1896终止变异率与eAg低组间差别有显著性意义 (P <0 0 5 )。结论　 (1)nt1896终止变异对eAg表达的影响高于CP双变异 (nt176 2 nt176 4 )。 (2 )nt172 6 - 1730CP聚集变异可能通过影响HBVX基因的表达产物HBx的结构变化 ,使HBx的调节作用发生改变 ,进而使其在顺式作用和或反式作用上影响HBV的复制、表达与致病     

A comparison of hepatitis B viral markers of patients in different clinical stages of chronic infection

Purpose  

Hepatitis B viral markers may be useful for predicting outcomes such as liver-related deaths or development of hepatocellular carcinoma. We determined the frequency of these markers in different clinical stages of chronic hepatitis B infection.     

干扰素治疗乙型肝炎病毒preC/C基因突变株感染的研究现状

检索1988年至1996年MEDLINE关于α-IFN治疗HBV preC/C基因突变株感染的资料,用Meta-analysis方法,评价α-IFN治疗血清抗-HBe和HBV DNA同时阳性患者的疗效。结果表明,α-IFN治疗HBV preC/C基因突变株感染是有效的,疗效与α-IFN治疗HBV野生株相似;α-IFN本身不引起HBV preC/C基因变异,但对混合感染者,α-IFN在消灭野生株的同时,有可能促使突变株成为体内优势毒株。