鸟苷结合蛋白1对柯萨奇病毒B3及乙型肝炎病毒体外介导的不同作用

目的构建人鸟苷结合蛋白1（hGBP-1）真核表达质粒，观察hGBP-1体外对柯萨奇病毒B3（CVB3）和乙型肝炎病毒（HBV）的抑制作用。方法长链RT-PCR扩增全长hGBP-1编码区基因，克隆到pCR2．1TA克隆载体，再亚克隆到pcDNA3．1（-）真核表达载体。体外转染HepG2细胞和Hela细胞，Western blot检测hGBP-1的表达。然后分别观察转染细胞中hGBP-1对HBV体外复制子pHBV1．3和CVB3的抑制作用。ELISA检测共转染HepG2细胞培养L清HBsAg、HBeAg水平；Southern blot检测细胞HBVDNA复制中间体。TCID50试验检测Hela细胞培养物中CVB3感染量。结果成功构建hGBP-1真核表达质粒，能在HepG2细胞和HeLa细胞进行高效表达。该质粒与pHBV1．3共转染HepG2细胞，不能抑制HBV复制，HBsAg、HBeAg及HBV DNA复制中间体水平与对照相比都无明显变化。转染质粒在HeLa细胞上对CVB3复制有明显的抑制作用，CVB3感染量显著降低，尤其在低剂量病毒攻击时能完全抑制CVB3复制。结论hGBP-1可能在IFN介导的抗CVB3中起重要作用，但不能抑制HBV的复制。     

HBV adr亚型体外感染肝细胞模型的建立

目的:构建1.1倍乙型肝炎病毒(HBV)全基因的真核表达载体,稳定转染L-02细胞,建立HBVadr亚型体外感染的细胞模型。方法:以pVUⅡ酶切质粒p3.6Ⅱ获得1.1倍HBV DNA片段,用牛小肠碱性磷酸酶将经EcoRV线性化的pcDNA3去磷酸化,以T4DNA连接酶连接1.1倍HBV DNA片段和线性化的pcDNA3,将构建的pcDNA3-1.1HBV以脂质体转染L-02肝癌细胞,经G418稳定筛选。ELISA检测转染细胞培养上清中HB-sAg、HBeAg的表达。RT-PCR检测转染细胞中HBpreS2、HBX的表达。结果:成功构建了1.1倍HBV全基因真核表达载体,稳定转染L-02后,建立了新的肝细胞系L-02.1Z,其培养上清中可检测到HBsAg、HBeAg的稳定表达,并可检测到HBpreS2、HBX RNA在转染细胞中表达。结论:该表达载体可介导病毒复制,其稳定转染的细胞可作为一种新型的HBV体外感染模型。     

含恩替卡韦耐药基因的HBV全基因组逆转录病毒载体的构建及包装

目的：构建含恩替卡韦耐药基因的HBV全基因组逆转录病毒载体,同时进行逆转录病毒载体的包装,为进一步产生含恩替卡位耐药基因的假病毒,进一步感染肝源性细胞,进行耐药机制的研究做准备。方法: 采用基因扩增、重组和克隆的方法,从构建好的含恩替卡位耐药基因的重组质粒中,扩增出含恩替卡位耐药基因的HBV全基因组,然后插到pLEGFP-N1载体上,再进行重组质粒的转化、提取、纯化和测序,然后将测序成功的重组质粒扩大培养,并转染PT67细胞,最后通过荧光倒置显微镜观察和提取细胞培养上清进行病毒DNA提取。结果: 凝胶电泳分析血清HBV DNA扩增可见3.2 kb条带,HBV DNA和pLEGFP-N1载体连接后可见10.1 kb目的条带,该重组质粒双酶切后可见3.2 kb和6.9 kb目的条带。突变前质粒测序显示含有HBV基因型为C型血清型adr的全基因组,突变后测序证实存在HBV逆转录酶169、184、202、250位点的预期碱基突变。荧光倒置显微镜显示,转染后的PT67细胞有明显的荧光表达,培养上清DNA提取后,经过核酸分析仪检测,最后换算结果显示培养上清假病毒颗粒可达104-105/cfu。结论: 成功构建了含恩替卡韦耐药基因的HBV全基因重组质粒,并进行了包装,产生了含恩替卡位耐药基因的假病毒颗粒。     

乙型肝炎病毒基本核心启动子及前C区突变与基因型的关系

目的　探讨乙型肝炎病毒 (HBV)基本核心启动子 (BCP)及前C区突变与基因型之间的关系。方法　随机选取 113例慢性HBV感染者外周血 ,采用INNO LiPA法测定BCPT176 2 A176 4双突变及前C区A1896突变 ,测定HBVS基因序列明确基因型。结果　在C基因型感染者中BCPT176 2 A176 4双突变率明显高于B基因型感染者 ,差异有显著性 (34.2 %∶10 % ,χ2 =6 .74 ,P <0 .0 1) ,而前C区A1896突变率在B基因型和C基因型感染者中差异无显著性 (2 .5 %∶4 .1% ,χ2 =0 .0 0 ,P >0 .0 5 )。结论　与B基因型相比 ,C基因型感染者更易发生BCPT176 2 A176 4双突变。     

肝癌高发区广西隆安县乙型肝炎病毒株全基因序列分析

目的 探讨肝癌高发区广西隆安县乙型肝炎病毒(HBV)株的全基因序列是否存在地域特殊性。方法 用套式PCR(nPCR)扩增该县HBV无症状携带者血清HBV全基因，用克隆测序法测序并做同源性对比。结果 本病毒株共3215个碱基，基因型为C，血清型为adw。其P基因区有40处发生碱基点突变，导致11个氨基酸改变；S基因区的前S1、前S2和S基因分别有11、2和3个碱基点突变，分别导致3、1、1氨基酸改变，未发现“a”区突变；X基因区共有6个碱基点突变，导致4个氨基酸改变，其中出现能影响e抗原表达的双突变(nt1762A→T、1764G→A)；未发现前C区基因突变，C基因有13个碱基发生突变，导致2个氨基酸改变。本病毒株与越南北部病毒株高于同为C基因型的上海株、北京株、西藏株。结论 未发现肝癌高发区的本例HBV基因C型的隆安株，基因虽有肝癌高发性，但无地域特殊性。     

胞嘧啶脱氨酶APOBEC3G可能通过G→A突变抑制乙型肝炎病毒的复制

目的研究胞嘧啶脱氨酶APOBEC3G(A3G)对HBV复制的影响及作用机制。方法利用脂质体介导A3G和HBV的真核表达质粒瞬时共转染人肝癌细胞株HepG2,以空载体pcDNA3.1与HBV真核表达质粒共转染为对照,同时转染含增强型绿色荧光蛋白(EGFP)基因的质粒载体以判定转染效率。共转染两天后用荧光定量PCR方法定量细胞内核壳体(core)相关HBV DNA水平,用Western blot检测细胞内A3G和HBcAg的表达,并对细胞内core相关HBV DNA X基因进行PCR扩增、T-A克隆和测序,分析X基因中的碱基突变。结果经EGFP判定的转染效率平均为29%。共转染0.5μgA3G和0.5μgHBV的HepG2细胞内core相关HBV DNA量平均下降为对照的8.9%,共转染2μgA3G和0.5μgHBV的平均下降为对照的0.6%。共转染A3G和HBV表达质粒后,HepG2细胞内HBV的X基因中发生G→A突变的数目明显增多,33个克隆中有9个克隆检测到了16～37个G→A突变,突变总数达254个,而对照的33个克隆中仅有2个克隆各检测到2个G→A突变。进一步的分析发现,共转染A3G后发生的G→A突变大多集中于几个热点区域,突变靶点常在GG二核苷酸中的第一个G上。结论胞嘧啶脱氨酶APOBEC3G可能通过诱导。HBV DNA的X基因发生G→A超突变,抑制HBV在人肝癌细胞HepG2中的复制。     

广西肝癌高、低发区人群乙型肝炎病毒核心基因启动子突变株的流行特征

目的　了解广西肝癌高、低发地区乙型肝炎病毒 (HBV)核心基因启动子突变株的流行特征。方法　用套式PCR(nPCR)扩增 77例广西原发性肝癌高发地区隆安县和低发地区桂林市人群HBV无症状携带者血清HBVDNA核心基因启动子 ,阳性者用直接测序法测序。结果　发现 77例HBsAg无症状携带者中 39例HBVDNA阳性 ,阳性率为 5 0 6 % (39 77)。隆安县标本HBVDNA阳性率为 5 5 6 % (2 0 36 ) ,其中 35 %标本核心基因启动子发生突变 ,常见的突变类型为双突变 (nt176 2A→T、nt 176 4G→A) ,占 2 5 % (5 2 0 ) ;桂林市标本HBVDNA阳性率为 4 6 3% (19 4 1) ,其中 4 7 4 %标本有突变 ,常见的突变类型也是双突变 ,占 4 19,两地区T1 76 2 A1 76 4突变株流行率差异无显著性 (P >0 0 5 )。结论　广西T1 76 2 A1 76 4突变株流行分布与肝癌发病率分布不成正相关关系。     

40例乙型肝炎患者HBV逆转录酶基因耐药突变分析与表达载体构建

目的 分析40例慢性乙型肝炎患者血清中HBV逆转录酶区基因耐药相关突变,构建突变基因重组表达载体用于表型耐药分析.方法 从服用抗HBV核苷(酸)类似物的患者血清中提取病毒DNA,PCR扩增HBV RT全长基因,克隆到pGEM-Teasy载体中,随机挑选3～5个克隆进行DNA序列测定,以DNASTAR软件分析RT基因内与核苷(酸)类似物耐药相关的常见突变位点.用Xho Ⅰ和Nco Ⅰ双酶切pGEM-Teasy-RT及pTriEx-HBV(C)构建1.1表达载体,测序正确后转染Huh7细胞,检测HBsAg和HBeAg表达水平.结果 40例患者均分别检出拉米夫定、阿德福韦、恩替卡韦耐药相关的单一或联合突变;成功克隆了96条HBV RT基因,分别带有上述核苷(酸)类似物耐药相关变异的序列;挑选主要突变组合形式的40条RT基因构建pTriEx-HBV(C)1.1表达载体,转染Huh7细胞48 h后在培养上清中检测到HBsAg和HBeAg,表明表达载体构建成功.结论 本研究成功进行了临床患者HBV耐药相关突变分析与突变体重组表达载体构建,为进行表型耐药分析打下了基础.     

C基因截短的HBV复制与包装

目的 探讨C基因截短型HBV变异体的复制与包装。方法 采用分子克隆、人工定点突变等技术构建C基因截短型HBV变异体质粒，用脂质体法转染HepG2细胞，提取细胞内及培养上清液中DNA分别进行Southem杂交，PCR及实时定量荧光PCR分析。结果 经DNA测序及酶切鉴定证实C基因截短型HBV质粒载体构建成功；C基因截短型HBV为复制缺损型，与辅助质粒共转染HepG2细胞，可在细胞内及培养上清液中检测到HBV各种DNA构型；DNA定量分析提示C基因截短型HBV的包装效率较野生型HBV提高3～40倍。结论 C基因截短型HBV变异体为复制缺损型，单独转染后不能在肝细胞内包装与复制，但在缺失包装信号ε的相应辅助病毒辅助下可有效复制并包装成子代病毒颗粒分泌到胞外，且包装效率大大提高。     

固有免疫分子TRIM5α对乙型肝炎病毒复制的影响

目的:构建固有免疫分子TRIM5α的真核表达质粒,研究TRIM5α 对HBV复制的影响.方法:通过巢氏RT-PCR技术从恒河猴肺组织中扩增出TRIM5α的编码基因,并将其克隆入pcDNA3.1真核表达载体.将TRIM5α真核表达质粒转染HepG2细胞,用Western blot的方法鉴定TRIM5α蛋白表达情况.将TRIM5α真核表达质粒与复制型HBV质粒通过磷酸钙沉淀法共转染HepG2细胞、通过尾静脉高压注射法共转染BALB/c小鼠.ELISA检测转染细胞上清及小鼠血清中的HBsAg和HBeAg;免疫组化检测小鼠肝组织HBcAg的表达;Southern blot检测转染细胞中HBV复制中间体.将TRIM5α真核表达质粒转染293T细胞3小时后,再将基于HIV-1结构的慢病毒载体三质粒系统转染293T细胞,通过检测转染细胞上清中的HIV-1 p24抗原含量来鉴定TRIM5α抗HIV-1功能.结果:成功构建TRIM5α真核表达质粒;过表达TRIM5α不能有效降低HBV抗原和复制中间体水平,但可抑制HIV-1 p24抗原的表达.结论:TRIM5α不能有效抑制HBV的复制.     

Influences on hepatitis B virus replication by a naturally occurring mutation in the core gene

Little is known about specific naturally occurring mutations of hepatitis B virus (HBV) and underlying mechanisms of their association with fulminant hepatitis. A HBV clone isolated from a patient with fulminant hepatitis was analyzed, and the features of the particular mutations observed around furin cleavage site in core region (A2339G/G2345A) were assessed using an in vitro replication model. The clone belonged to genotype B with precore stop codon mutation (G1896A). Replication efficiency of 1.24-fold HBV genome in Huh-7 cells was increased in the presence of A2339G. Further in vitro studies using furin inhibitor indicated that the effect of the mutation was probably associated with accumulation of the full-length core protein without cleavage by furin-like protease, suggesting that a processing of the core protein might play an important role in regulation of viral replication. In conclusion, the A2339G mutation was considered as one of the viral factors involved in high replication efficiency.     

乙型肝炎病毒剪接特异性蛋白对病毒自身调控序列的影响

目的 研究双剪接型2.2 kb乙型肝炎病毒(HBV)剪接变异体特异性蛋白TPds对病毒自身调控序列的影响.方法 PCR扩增6种HBV启动子/增强子序列,以Kpn Ⅰ及Xho Ⅰ位点克隆于pGL3-basic,分别构建萤火虫荧光素酶重组报告载体pGL3-BCP(含HBV基本核心启动子)、pGL3-CP1601(含增强子Ⅱ的核心启动子)、pGL3-XP(X基因最小启动子)、pGL3-XP1071(含增强子Ⅰ的X基因启动子)、pGL3-SP1(表面抗原大蛋白基因启动子)、pGL3-SP2(表面抗原中蛋白基因启动子).以FuGENE6将TPds表达载体pcDNA3.1/HisC-TPds或空白载体pcDNA3.1/HisC分别与6种HBV启动子/增强子报告载体共转染Huh7细胞,转染后48 h裂解细胞并检测胞内萤火虫荧光素酶活性,实验重复5次,数据以SPSS11.5软件分析.结果 在一定的质量比值范围内,与pcDNA3.1/HisC空白载体对照相比,pcDNA3.1/HisC-TPds分别与pGL3-CP1601、pGL3-XP1071、pGL3-SP1、pGL3-SP2共转染后,Huh7细胞内萤火虫荧光素酶活性增高,而pcDNA3.1/HisC-TPds分别与pGL3-BCP或pGL3-XP共转染后,胞内荧光素酶活性无变化.结论 TPds蛋白可反式激活HBV启动子SP1、SP2和增强子Ⅰ、Ⅱ,对基本核心启动子和X基因最小启动子无影响.     

Hepatitis B virus harboring nucleotide deletions in the core promoter region and genotype B correlate with low viral replication activity in anti-HBe positive carriers.

BACKGROUND: Emergence of anti-HBe following seroconversion of HBe antigen indicates reduced hepatitis B virus (HBV) replication in the liver and low infectivity in the natural course of infection. However, some patients show continued replication or reactivation even in the presence of anti-HBe. OBJECTIVE: To clarify the cause of HBV replication, we investigated genotype differences and mutations in the core promoter and precore region in relation to virus titer. STUDY DESIGN: Using quantification of HBV DNA, nucleotide sequencing of the core promoter and precore region, and genotyping with the S gene by restriction fragment length polymorphism (RFLP), we analyzed sera of 26 anti-HBe positive carriers (28 serum samples). RESULTS: Various mutations were detected including C to T point mutation at nt 1653, A to T and G to A contiguous point mutations at nt 1762 and 1764 in the core promoter region, and G to A point mutation at nt 1896 in the precore region, but no common mutations were detected that were directly related to the virus titer from earlier reported mutations. In contrast, the mean titer of genotype B virus was 1.5 x 10(5) copies per ml and that of mutant HBV of genotype C having 8 base pairs (8-bp) deletion (nt 1768-1775) in the core promoter region was 7.9 x 10(4) copies per ml (mean titer). These titers showed commonly lower than that of genotype C virus without 8-bp deletion (median titer 5.0 x 10(6) copies per ml). Transition of genotype from C to B after viral reactivation and reduction of proportion of 8-bp deletion mutant at reactivation period was observed in a patient who demonstrated exacerbation of liver dysfunction due to immunosuppressive therapy and increased viral replication. CONCLUSIONS: These results confirm those of our earlier study describing low replication ability of 8-bp deletion mutant HBV in vitro, and also indicate that the presence of genotype B correlates with reduced titer of HBV.     

Evolution of viral load and changes of polymerase and precore/core promoter sequences in lamivudine-resistant hepatitis B virus during adefovir therapy

Adefovir dipivoxil (ADV) has demonstrated clinical activity against both wild-type and lamivudine-resistant hepatitis B virus (HBV). We analyzed the evolution of viral load and the changes of polymerase and precore/core promoter sequences in lamivudine-resistant virus during ADV therapy. The authors studied 14 patients who had breakthrough hepatitis after lamivudine therapy. Serial sera were obtained prior to adefovir administration and at 3, 6 and 12 months after ADV therapy. Nucleotide sequences of polymerase and the precore/core promoter from the hepatitis B virus were analyzed. The median serum HBV DNA decrease with adefovir treatment was 4.35 log(10) copies/mL at 12 months. Tyrosine-methionine-aspartate-aspartate (YMDD) mutants were found in 12 patients among the 14 patients with lamivudine resistance. The YMDD mutant viruses reversed to the wild-type in 6 patients out of the 12 patients after 3-6 months of ADV after discontinuing lamivudine therapy. In the analysis of the nucleotide sequences of the precore/core promoter gene, core promoter mutants in 12 patients were replaced by wild-type virus in three patients (25%), while precore mutants in four patients were replaced by the wild-type in three patients (75%). The results demonstrate the patterns of polymerase and precore/core promoter mutations in lamivudine-resistant hepatitis B viruses and the reversion from the mutant to the wild-type in some patients. In addition, despite several mutations in the polymerase during ADV therapy, ADV effectively suppressed HBV replication without the emergence of resistant viral mutants.     

Precore/core promoter mutations and genotypes of hepatitis B virus in chronic hepatitis B patients with fulminant or subfulminant hepatitis

The association of precore stop codon mutation (A1896), dinucleotide mutation (T1762/A1764) in the basic core promoter of hepatitis B virus (HBV) genome, and genotype of HBV with fulminant or subfulminant hepatitis remains controversial. We studied HBV genotypes as well as mutations in the precore and basic core promoter regions in 18 hepatitis B carriers with fulminant or subfulminant hepatitis. Genotyping of HBV was performed by polymerase chain reaction-restriction fragment length polymorphism. The presence of A1896 in the precore gene and T1762/A1764 in the basic core promoter gene was determined by the polymerase chain reaction and by direct sequencing. Eighteen age- and sex-matched patients with chronic active hepatitis B served as controls. The HBV was of genotype B in 14, genotype C in 3, and unclassified in 1. Precore A1896 mutation occurred in 12 (67%) of the 18 patients. In contrast, the prevalence of basic core promoter mutation was only 17%. Nevertheless, the distribution of HBV genotype and the prevalence of precore A1896 mutation in the fulminant and subfulminant hepatitis patients were similar to those in 18 control patients. In conclusion, the genomic variability of HBV does not seem to contribute to the fulminant and subfulminant exacerbation of chronic hepatitis B in Taiwanese HBV carriers.     

Two distinct types of hepatitis B virus core promoter variants in Yemeni blood donors

Genetic variations in the basic core promoter (BCP) region of hepatitis B virus (HBV) occur during the natural history of chronic HBV infection. This study investigates the presence of basic core promoter variations in 28 asymptomatic Yemeni blood donors, correlating variations with HBeAg phenotype and viral load. The core promoter/precore and surface gene region of HBV DNA were amplified using nested PCRs and the PCR products were sequenced either directly or after cloning. HBeAg and viral load were measured when HBV DNA was detectable. Sequencing of 18 surface PCR products indicated that all were of genotype D. Two distinct types of variants were identified in the basic core promoter: substitution only (N = 14) and major deletion (N = 9). The commonest substitutions were located at nucleotide positions 1753, 1762, and 1764; 10/14 (71.4%) were associated with the precore 1896A substitution resulting in the premature stop of the precore reading frame and 6/14 (42.9%) had viral loads above 400 copies/ml. Two forms of deletion variants were found: 8 bp deletion (1763-1770) (N = 2) and a novel 12 (1746-1757) + 8 bp (1763-1770) deletion (N = 7). The deletion sequences were never associated with the precore 1896A substitution and all had viral load below 400 copies/ml with negative HBeAg phenotype. The polymorphism 1773C was found in 9/14 (64.3%) substitution sequences whereas all deletion sequences had 1773T. Two donors had mixed sequences of basic core promoter substitution and major deletions (both 8 bp and 12 + 8 bp). While the deletion variants in these two donors were similar to others found in isolation, the substitutions were of a different pattern. Further studies are required to understand the selection process behind these variants.     

Mutations in the Basal Core Promoter and Precore/Core Gene of Hepatitis B Virus in Patients with Chronic Active but not Acute Hepatitis B

 Around 5–10% of adults infected with hepatitis B virus (HBV) develop a chronic liver disease such as chronic active hepatitis (CAH), and it is unclear whether the clinical outcome depends solely on the immune response or whether viral factors also play a role. In this study, a search was therefore made for nucleotide mutations in the basic core promoter (BCP) and amino-acid substitutions in the precore/core region of HBV infecting patients with CAH or with acute hepatitis. The nucleotide sequences of the BCP and of the precore/core region were determined in virus from ten patients with CAH and ten with acute hepatitis. The precore/core sequences were also analysed in 14 additional patients (6 with CAH, 8 with acute hepatitis). In seven of the ten patients with CAH, five types of mutations were found in the BCP. Deletions in the precore/core region were observed in six patients. In all six patients where only the precore/core region was studied, amino-acid substitutions were present. In contrast, in the ten patients with acute hepatitis studied for BCP, a mutation was found in the BCP of one patient only. Of the 18 patients in whom the precore/core was studied, three had an amino-acid substitution in this region. The results show a clear link between CAH and both HBV BCP and precore/core region mutations, suggesting these mutations may play a role in the persistence of HBV infection.