丙型肝炎病毒包膜基因变异与急性丙型肝炎疾病转归的动态研究

目的探讨HCV包膜基因变异与急性丙型肝炎疾病转归的关系。方法前瞻性收集到5例HCV急性感染者的系列血清标本,其中2例一过性感染,3例持续性感染。采用高精确度DNA聚合酶,较长PCR扩增HCV基因组结构区(包括C区C端、E1和E2区N端)1 kb产物并进行克隆,每份标本挑选33个克隆,以异源双链和单链构象多态分析筛查的代表性克隆型DNA进行测序,并对HCV的E1、HVR1及HVR1除外的E2区核酸序列的非同义碱基替换率、同义碱基替换率以及氨基酸序列的理化特征进行分析。结果HCV持续性感染者急性期与慢性期的标本比较,HVR1基因差异性明显大于E1 (0.0322±0.0068 vs-0.0020±0.0014,P<0.05)和HVR1以外的E2区(0.0322±0.0068 vs 0.0017±0.0011, P<0.05),而一过性感染者感染初期与病毒清除前标本比较,HVR1、E1和HVR1以外E2基因差异性则无明显改变。HCV持续性感染者的E1(0.23×10-3±O.15×10-3)、HVR1(2.76×10-3±1.51×10-3)和HVR1以外E2区(0.50×10-3±0.10×10-3)的非同义碱基替换率比较,HVR1非同义碱基替换率呈明显增高趋势。相反,一过性感染者E1、HVR1和HVR1以外E2区的同义碱基替换率和非同义碱基替换率则无明显改变。E1、E2区所有半胱氨酸及潜在的糖基化天冬酰胺均高度保守,HVR1第11、25、27位置保持碱性氨基酸。结论HCV持续感染与宿主免疫反应对HVR1的阳性选择相关,HVR1区特异位置保守的碱性氨基酸可供研制HCV疫苗时参考。     

丙型肝炎病毒包膜2区准种复杂性及其临床意义初探

目的 研究丙型肝炎病毒（HCV）包膜2（E2）区准种复杂性及其临床意义。方法 以9例不同血清丙氨酸转氨酶水平物急性HCV感染者和4例慢性丙型肝炎患者为对象，通过逆转录PCR扩增HCVE2区氨基端片段（560bp)，扩增产物直接克隆，以单链构象多态性（SSCP）/异质性双体（HD）分析对每份血清标本的30个克隆进行筛选及准种复杂性分析，结果 慢性丙型肝炎患者血清HCV准种复杂性明显增高：HCV感染者血清ALT水平变化与准种复杂性无明显关系。结论 HCVE2区准种复杂性与病毒持续性感染有关。征收肝损害程度无关。     

慢性1b型丙型肝炎病毒感染者包膜2基因正选择位点分析及功能意义

目的:纵向分析自然免疫压力下慢性1b型HCV感染者E2基因的系统进化模式及正选择位点,初步探讨E2基因正选择位点的分布与已知功能区之间的关系。方法:未抗病毒治疗的3例慢性1b型HCV感染者及其系列血清样本均来自中国人HCV感染患者系列标本库(CQueen cohort)。对每例感染者3个连续时间点的血清样本进行HCV5′端6000bp基因组的扩增、克隆,每个时间点随机挑选25～33个克隆对E2基因测序,用MEGA软件构建系统进化树,用固定效应似然法检测HCV E2基因的正选择位点。结果:3例HCV慢性感染者的9份血清样本均获清晰、无杂带的6030bp的目的片段。慢性HCV感染者体内病毒准种的复杂程度并非随着感染时间的延长而进行性增加,在某个时间点上准种变异株的序列可能会趋于一致。准种优势变异株在间隔半年时间以上已发生更替。对每位患者动态的准种变异株进行正选择位点的分析,共检测到5个氨基酸(aa)位点:aa384、aa399、aa410、aa475和aa522,分布于HCV E2基因HVR1区、HVR2区及HCV E2-CD81分子结合区。结论:基于动态变化的HCV准种优势株的相关研究,可考虑选择间隔半年以上时间点的血清样本作为研究对象。慢性HCV感染过程中,HCV E2基因位于重要功能区的aa位点受到了宿主强烈的免疫压力,aa384、aa399及aa410位点的变异可能导致HCV发生体液免疫逃逸;而aa475和aa522位点的变异则可能通过影响HVR2区的功能或HCV E2-CD81分子的亲和力或改变CD81分子的结构而导致HCV发生先天免疫逃逸。该研究为分析HCV C-NS3基因片段的正选择位点奠定了良好的基础。     

1b型丙型肝炎病毒基因组不同区域基因变异对干扰素疗效的影响

本研究对14例基因型1b型慢性丙型肝炎患者血清HCV基因组中E2/NS1(含HVR1和HVR2)、NS5A区准种异质性进行了检测,对HVR区准种异质性程度与干扰素(IFN)疗效的关系、NS5A2209-2248区是否存在干扰素敏感决定区(ISDR)等热点问题进行了探讨,为1b型慢性丙型肝炎患者应用IFN抗病毒治疗时     

慢性丙型肝炎患者HCV HVR1准种异质性与干扰素疗效关系的研究

目的：研究HCV HVR1准种异质性与干扰素疗效以及与HCV RNA载量之间的关系，为临床选择应用干扰素抗病毒治疗适应症及预测疗效提供理论依据。方法：采用核苷酸序列测定法进行HCV基因分型；分别采用单链构象多态性聚合酶链反应法（SSCP）及克隆测序法进行HVR1准种异质性检测；采用荧光特异性PCR法进行HCV RNA载量检测。结果：14例1b型慢性丙肝患者干扰素治疗前5例为SSCP低复杂性（SSCP条带数≤3），9例为高复杂性（SSCP条带数＞3），干扰素治疗应答组SSCP条带数明显少于无应答组。1b型患者中无应答组HVR1变异株的数目（准种数）和基因的差异性（每个基因位点的平均变异率）均明显高于应答组。HVR1准种异质性程度与HCV RNA含量无正相关关系。结论：感染HCV基因型1b型的慢性丙型肝炎患者HVR1准种异质性程度越高对干扰素无应答的可能性越大。HVR1准种的复杂性程度与HCV RNA含量无关，是预测干扰素疗效的一个独立因素。     

丙型肝炎病毒准种多样性与病毒血症水平、疾病活动度及干扰素疗效的关系

目的　了解丙型肝炎病毒 (HCV)准种变异与病毒血症水平、疾病活动度及干扰素疗效的关系。方法　采用针对HCVE2高变区 1 (HVR1 )的单链构象多态性分析法 (SSCP)对 68例慢性丙型肝炎患者进行HCV准种检测 ,分析准种数目与HCVRNA、ALT、AST水平及肝组织活动指数 (HAI)的相关性。对其中 48例给予干扰素治疗 ,分析准种数目对干扰素应答效果的影响。结果　 61例HVR1SSCP阳性 ,HCV准种数目为 (6 2± 2 4)条。准种数量与HCVRNA水平显著相关 (P <0 0 1 ) ,与ALT、AST及HAI无明显相关 (P >0 0 5)。干扰素治疗患者中 ,43例HVR1阳性 ,持续应答者治疗前HCV准种数量 (3 3± 1 2 ,n =1 1 )显著少于获得治疗终点应答 (ETR)伴复发者 (6 3± 2 2 ,n =1 2 ,P <0 0 5)或无应答者 (8 0± 3 3 ,n=2 0 ,P <0 0 1 )。治疗结束时 ,干扰素组仍有 1 6例检测出HCV准种 ,但准种条数降为 (3 4± 1 2 )条 ,与未接受干扰素治疗病例的准种数目 (6 8± 2 5)相比差异有显著性 ,P <0 0 1 ) ,且其中 1 0例准种模式发生了改变。结论　HCV准种多样性可引起较高的病毒血症水平 ,但与疾病活动度无关 ;准种数目可作为预测慢性丙型肝炎干扰素疗效的指标。     

HCV第一高变区的免疫学研究进展

HCV属黄热病毒科,感染人体后可引起机体免疫应答发生异常,导致组织损伤,形成慢性持续性感染,并能进一步发展为肝硬化甚至肝细胞肝癌.目前全世界约有1.7亿HCV感染者,约有75%左右的急性丙型肝炎患者转为慢性感染,其中10%～20%慢性丙型肝炎患者发展为肝硬化,1%-5%发展为肝癌[1].丙型肝炎在治疗和预防方面具有很强的局限性,这主要是由于HCV的高度变异性,其中位于E2 NS1区N端第27位氨基酸的变异性最大,通常称之为第一高变区(hypervariable region 1,HVR1).研究证明HVR1中含有优势表位[2],其高度变异性也将对机体产生的针对HCV的细胞和体液免疫应答造成障碍.现本文就近年来有关HCV-HVR1的免疫学研究进展做一综述.     

HCV第一高变区的免疫学研究

 HCV 属黄热病毒科，感染人体后可引起机体免疫应答发生异常，导致组织损伤，形成慢性持续性感染，并能进一步发展为肝硬化甚至肝细胞肝癌。目前全世界约有 1.7 亿 HCV 感染者，约有 75% 左右的急性丙型肝炎患者转为慢性感染，其中 10% ~ 20% 慢性丙型肝炎患者发展为肝硬化，1% ~ 5% 发展为肝癌^[1]。丙型肝炎在治疗和预防方面具有很强的局限性，这主要是由于 HCV 的高度变异性，其中位于 E2 NS1 区 N 端第 27 位氨基酸的变异性最大，通常称之为第一高变区（hypervariable region 1，HVR1）。研究证明 HVR1 中含有优势表位^[2]，其高度变异性也将对机体产生的针对 HCV 的细胞和体液免疫应答造成障碍。现本文就近年来有关 HCV-HVR1 的免疫学研究进展做一综述。......     

不同治疗效果的艾滋病患者抗病毒治疗前HIV-1gp120准种特征差异

目的 探讨HIV-1 gp120准种在不同治疗效果的艾滋病患者抗病毒治疗前的特征差异.方法 回顾性收集治疗方案为AZT+NVP+3TC的艾滋病患者在抗病毒治疗前的血浆样本,包括病毒抑制(VS)组12例,治疗失败(TF)组12例.采用单基因组扩增技术获得gp120准种序列,分析比较遗传多样性、氨基酸长度、潜在糖基化位点及特征性氨基酸的特点.结果 本研究共获得gpl20序列365条序列,其中VS组168条(6-20条),TF组197条(7-28条).TF组的gp120准种复杂度高于VS组,差异有统计学意义(P=0.003);TF组的gp120准种dS及dN中位数均高于VS组(P=0.017;P=0.002).TF组HIV-1准种gpl20氨基酸长度长于VS组(P=0.00l).TF与VS组的gpl20准种相比共有9个氨基酸位点存在明显差异,多数分布在V1/V2区(6/9,66.6％).结论 不同治疗效果的艾滋病患者治疗前的HIV-1 gp120准种基因特征存在差异,TF组患者来源的HIV-1准种遗传多样性更高.     

不同感染途径慢性丙型肝炎患者HCV基因型分布的差异

目的 探讨丙型肝炎病毒(HCV)基因型在中国部分城市输血与非输血途径感染者之间的分布。方法 对来自中国南北地区9个城市的慢性HCV肝炎患者的血清，用5′非编码区酶切分型方法进行HCV基因分型，分析HCV基因型在不同地区和感染途径之间的分布差异。结果 在219例慢性HCV肝炎血清中，有214例(97．7％)检测出HCV基因型，其中197例为单基因型HCV感染，主要的HCV流行株为1b(76．64％)和2a(18．22％)，并有5．14％的患者感染基因3b型，且首次在中国检测出4a型。HCV在中国南北地区城市的分布差异无显著意义，但输血感染者和非输血感染者之间的HCV基因型分布差异有显著意义，输血感染者中，93．88％为单基因型HCV感染，1b占76．87％，高于非输血途径感染患者中单基因型HCV感染百分率(86．57％)和1b的感染百分率(58．21％)，非输血感染者中的混合HCV基因型比例(13．43％)高于输血感染者(6．12％)。结论 中国南北部分地区的HCV基因型分布差异无显著意义，但经输血感染和非输血感染的慢性丙型肝炎患者之间的HCV基因型分布差异有显著意义。     

Genetic characterization of hypervariable region 1 in patients chronically infected with hepatitis C virus genotype 2.

The hypervariable region 1 (HVR1) has been most reliably identified in the genome of HCV genotype 1 isolates and thought to possibly play a role in immune evasion and development of chronic infection. There are few studies, however, of other HCV genotypes to determine if they also have such a hypervariable region present, and it is unclear whether or not there is any genotype-dependent difference in the genetic characteristics of HVR1. We determined the nucleotide sequence of 5' end of E2/NS1 region of the HCV genome spanning HVR1 of multiple genotype 1 and 2 HCV isolates and carried out a detailed genetic analysis. Similarity plots identified two hypervariable regions within the genotype 2 sequences, a larger one corresponding to HVR1 as well as a smaller 27-nucleotide region of hypervariability. The synonymous substitutions per synonymous site (ds) was greater than nonsynonymous substitutions per nonsynonymous site (dn) within genotype 1 group whereas dn and ds were similar in the genotype 2 group. Analysis of amino acid sequences revealed several conserved sites across genotype 1 and 2 (amino acid numbers 2,6, 20 and 26) and overall similar hydropathic profiles were found within two genotypes. Still, despite the hypervariability, the HVR1 showed a genotype-specific phylogenetic clustering. Thus, HVR1 appears to be conserved between genotypes in keeping with it having an important survival function. Genotype 2 appears to have a greater rate of nonsynonymous substitutions within HVR1, suggesting a greater positive evolutionary pressure.     

Higher dN/dS ratios in the HCV core gene, but not in the E1/HVR1 gene, are associated with human immunodeficiency virus-associated immunosuppression

Coinfection with HCV and HIV is prevalent among former commercial blood donors in some rural areas in China. Genetic variability of the HCV core and E1/HVR1 was investigated in 23 patients chronically infected with HCV-1b, with or without concomitant HIV infection. Genetic variability in the core sequence was higher under HIV-associated immunocompromised conditions. Both the Shannon entropy values at each nucleotide position and the dN/dS values at each codon were statistically higher in HIV/HCV-coinfected patients with lower CD4+ T cell counts (p-values were <0.0001 and equal to 0.0372, respectively). The more significant difference of dN/dS value occurred in a specific subregion of the core gene that is enriched in CTL/Th epitopes (p?=?0.0083). The dN/dS values of full-length core antigen were found to be negatively correlated with the S/CO ratio of plasma anti-HCV antibodies. By contrast, no significant difference in genetic diversity/complexity and dN/dS values in the E1/HVR1 region was found between those two groups. These results suggest that the dN/dS ratio in the core gene, but not in the E1/HVR1 gene, is influenced more by host CD4+ T cell–mediated cellular immunity.     

A highly hydrophobic domain within hypervariable region 1 may be related to the entry of hepatitis C virus into cultured human hepatoma cells

Interaction of the envelope glycoprotein of hepatitis C virus (HCV) with a cellular receptor(s) is thought to be essential for the initial steps of HCV infection. However, the mechanisms of HCV infection remain unclear. The aim of the present study was to determine the features of HCV that enable efficient entry of the virus into human hepatocytes. Variations of hypervariable region 1 (HVR1) sequences in HCV inocula and in infected human hepatoblastoma HepG2 cells were examined. Immunofluorescence of inoculated HepG2 cells with anti-HCV core antibodies demonstrated that HCV structural proteins were expressed in the cytoplasm, and their entry into HepG2 cells was confirmed. When the HVR1 amino acid sequences were compared, HVR1 quasispecies in the inoculated cells showed more uniformity than those of the inocula. Although there were no statistically significant differences between the two groups, hydrophobic residues were observed more frequently in the HVR1 amino acids from inoculated cells than in the HVR1 amino acids from the inocula. Results of hydropathy analysis revealed that highly hydrophobic domains exist in the middle of HVR1 in the inoculated cells in 7 of 10 patients. The results suggest that limited HCV populations are able to enter HepG2 cells and that the highly hydrophobic domain existing within the HVR1 may play an important role in the entry of HCV into cells.     

B-cell epitopes in hypervariable region 1 of hepatitis C virus obtained from patients with chronic persistent hepatitis

The hypervariable domain (HVR1) within the N-terminus of the E2 protein of hepatitis C virus (HCV) is known to be variable antigenically during the course of persistent infection. The aim of the study was to detect B-cell epitopes in HVR1 responsible for neutralizing HCV. The B-cell epitopes were analyzed using two series of synthetic peptides: 25 heptapeptides from the most common amino acids within 73 HVR1 sequences, and 216 heptapeptides, the sequences of which cover more than 65% of the 73 HVR1 sequences. Sera from three patients with chronic hepatitis C were tested for reactivity to the synthetic peptide sequences by enzyme-linked immunosorbent assay (ELISA). The post-interferon (IFN) serum of one patient who had a long-term response to treatment reacted specifically with 13 heptapeptides of 216 variable sequences of HVR1. Some of the amino acid sequences (amino acids 398, 399, 400, 404) of the heptapeptides were also found in those deduced from the nucleotide sequences of HCV genomes in the pre-IFN serum. The sera of the other two patients who did not respond to treatment did not react with the 13 heptapeptides. It is concluded that the B-cell epitopes in HVR1 may be relevant for eliminating viremia in the case of the patient who had a good response to treatment. These results suggest that the analysis of the B-cell epitopes recognized in HVR1 may be important in understanding the mechanism of persistent infection and progression of hepatitis. © 1996 Wiley-Liss, Inc.     

Genetic diversity of hepatitis C virus quasispecies in chronic renal failure patients in Midwest Brazil

Hepatitis C virus (HCV) quasispecies constitute a dynamic population in a continuous process of variation and selection. To investigate effect of the immune system on the genetic variability of HCV, we compared the hypervariable region 1 (HVR1) of immunosuppressed patients with chronic renal failure (CRF group) to immunocompetent patients with HCV chronic infection (control group). The HVR1 from ten samples of each group was amplified, cloned and sequenced. The HCV quasispecies from the control group had a higher frequency of variable sites in HVR1 (83.9 % vs 59.3 %, p < 0.05), as well as a greater diversity within (intra-patient) and between samples, compared to the CRF group. The clustering of the majority of the quasispecies of the CRF group in the phylogenetic tree also showed the limited diversity of the quasispecies in immunosuppressed patients. Moreover, a higher variability of amino acids at positions 384, 386, 391, 394, 397, 398, 400, 405 and 410 was observed in the control group than in the CRF group, which showed a greater variability only at position 388 (p < 0.05). These data corroborates the hypothesis that the major selective pressure factor is the immune system, which promotes a high degree of diversity in the viral progeny and contributes to a constant evolution of HCV.     

HCV准种多样性及其与临床关系的研究

目的     

Genetic complexity of the hypervariable region 1 (HVR1) of hepatitis C virus (HCV): Influence on the characteristics of the infection and responses to interferon alfa therapy in patients with chronic hepatitis C

HCV exists within its host as pools of related genetic variants referred to as quasispecies. The hypervariable region 1 (HVR1) of the E2 envelope gene is subjected to strong selective pressure from neutralizing antibodies. The genetic complexity of this region is defined as the total number of genetic variants within the quasispecies population. The genetic complexity of the HVR1 region was examined in patients with chronic hepatitis C and its relationship with the epidemiology of HCV infection, and its influence on liver disease and the response to interferon treatment were determined in 114 patients with chronic hepatitis C. The genetic complexity of the HVR1 major variants was measured before treatment by using a polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) technique, and was compared with epidemiological, clinical, virological and histological features. The patients were treated with 3 megaunits of interferon (IFN) alfa for 3 to 6 months and the response to treatment was assessed at 3, 6 and 12 months. The HVR1 could be studied in 101 of the 114 patients (89%). Genetic complexity was significantly higher in patients infected through blood transfusion than intravenous drug use (mean complexity index: 5.7 ± 2.3 vs. 4.7 ± 1.5, respectively; P = 0.04). This relationship was independent of age and the estimated time since infection. No significant relationship was found with other parameters of infection or liver disease. In univariate analysis, the genetic complexity of HVR1 major variants did not affect the rates of ALT normalization at months 3 and 6 of IFN treatment. HVR1 genetic complexity was lower in patients with a sustained virological response than in non-responders (4.0 ± 1.7 vs. 5.4 ± 2.0, respectively; P = 0.07). In multivariate analysis of pretreatment parameters associated with a sustained virological response to treatment, three parameters appeared to be independent predictors of such a response: a low viral load (P < 0.04), a low anti-HCV core IgM titer (P = 0.03) and a low genetic complexity of HVR1 major variants (P < 0.04). In conclusion, the HVR1 of HCV has a quasispecies distribution in infected individuals. Its genetic complexity is significantly higher in transfusion recipients than in intravenous drug users, suggesting that the size of the initial inoculum affects the later emergence and development of viral quasispecies. The genetic complexity of HVR1, together with viral load and the anti-HCV IgM titer, are independent predictors of a sustained virological response to IFN alfa in patients with chronic hepatitis C. J. Med. Virol. 54:256–264, 1998. © 1998 Wiley-Liss, Inc.     

Sequential change of the hypervariable region of the hepatitis C virus genome in acute infection

Hepatitis C virus (HCV) infection is characterized by persistence of liver inflammation that often leads to end-stage liver disease, although the mechanisms are not fully understood. A hyper-variable region (HVR) has been reported in the E2/NS1 region of the HCV genome, in which striking diversity is found among different HCV isolates. To investigate the association of the HVR alterations with the clinical courses of HCV infection, a longitudinal analysis of the HVR in patients with acute HCV infection was carried out. Plasma samples were obtained at several times in three patients with acute hepatitis C. Plasma RNA was extracted and reverse transcribed, and DNA fragments that included the HVR were amplified by PCR. The sequences of the HVR were directly determined from the PCR products by the dideoxy chain termination method, from which amino acid sequences were deduced. In all cases, plasma HCV-RNA disappeared with the improvement of the initial alanine aminotransferase (ALT) elevation, but HCV-RNA reappeared about 1 year later with or without deterioration of the hepatitis. In a case of sporadic acute hepatitis, the HCV in the recurrent phase had seven amino acid substitutions in the HVR compared with that in the acute phase, although no amino acid changes were noted during the initial acute phase. In a case of posttransfusion hepatitis, a marked difference was observed between the acute and the recurrent phases, with an amino acid homology of 30% (8/27). The mutation rate of the HVR had a tendency to accelerate as the HCV infection progressed to the chronic stage. In conclusion, the HVR changes serially during the course of acute HCV infection, and these HVR changes may play a part in the chronicity of HCV infection. © 1994 Wiiey-Liss, Inc.     

Antibody responses against B-cell epitopes of the hypervariable region 1 of hepatitis C virus in self-limiting and chronic human hepatitis C followed-up using consensus peptides.

A rare collection of serum samples from patients with hepatitis C virus (HCV) infection followed up from the onset of clinical symptoms was acquired. RNA corresponding to the hypervariable region 1 (HVR1) of E2 protein of HCV isolated from nine patients was reverse-transcribed, amplified, sequenced, and HVR1 amino acid sequences were deduced. These sequences and a selection of HVR1 amino acid sequences of matching HCV genotypes from protein and translated DNA sequence databanks were used to create the HVR1 amino acid consensus. The degenerated peptides mimicking N- and C-termini of the consensus were synthesized. Most (76%) of 17 patients followed up for the period from 1 week to a minimum of 7 months from the onset of acute symptoms developed antibodies reacting with peptides representing N- and/or C- termini of HVR1. Antibody recognition of the consensus HVR1 peptides indicates that the variability of HVR1 sequence on the protein level is limited with certain conserved structure(s) being untouched. A tendency was observed for a slower development of anti-HVR1 antibody response in patients developing chronic HCV, as compared to those with self-limiting HCV infection.