Dynamics of hepatitis B virus resistance to entecavir in a nucleoside/nucleotide-naïve patient

The genotypic evolution of HBV quasi-species was analyzed in a nucleoside/nucleotide-na?ve patient who developed resistance to entecavir. The lamivudine resistant quasi-species (rtM204V+/-rtL180M), absent at baseline, were emerged as early as 48 weeks after entecavir administration. Entecavir-resistant quasi-species (rtM204V+/-rtL180M plus S202G) were found after week 112 and gradually became the predominant mutations afterwards. The lamivudine- and entecavir-resistant mutations emerged closely in combination with the rtV207L, rtA222T, rtP237T or rtI163V substitutions. Our results indicated that the lamivudine-resistant mutations were developed first and may serve as a prequisite for subsequent entecavir-resistant mutations in this nucleoside/nucleotide-na?ve patient.     

石家庄地区乙型肝炎病毒基因分型及P区耐药基因突变分析

目的:分析石家庄地区乙型肝炎病毒(HBV)基因型分布以及核苷(酸)类似物耐药基因突变状况。 方法:对2011年1月-2013年12月在石家庄市五医院就诊的遵医嘱口服核苷(酸)类似物6个月以上的354例慢性乙型肝炎患者进行HBV P区基因序列测定。结果:HBV B型为17例(4.8%),C型为337例(95.2%);共检出突变182例,在B型中检测出有10例突变(58.8%),在C型中检测出有172例突变(51.1%),两组间突变率无显著差别;182例HBV P区存在突变的病例中以rtL180M+rtM204I/V/S联合突变最多,占突变比例24.2%;其次是rtM204I/V/S单位点突变,占突变比例20.3%,这两种突变模式的比例达到44.5%;第3位是rtL180M+rtM204I/V/S 再加上其他一个或多个位点的突变,占突变比例12.6%。结论:石家庄地区HBV基因型以C型为主;核苷(酸)类似物耐药基因突变以拉米夫定和替比夫定耐药最常见。     

Establishment of drug-resistant HBV small-animal models by hydrodynamic injection

In antiviral therapy of hepatitis B virus (HBV) infection, drug resistance remains a huge obstacle to the long-term effectiveness of nucleoside/tide analogs (NAs). Primary resistance mutation (rtM204V) contributes to lamivudine (LAM)-resistance, and compensatory mutations (rtL180M and rtV173L) restore viral fitness and increase replication efficiency. The evaluation of new anti-viral agents against drug-resistant HBV is limited by the lack of available small-animal models. We established LAM-resistance HBV replication mice models based on clinical LAM-resistant HBV mutants. Double (rtM204V+rtL180M) or triple (rtM204V+rtL180M+rtV173L) lamivudine-resistant mutations were introduced into HBV expression vector, followed by hydrodynamic injection into tail vein of NOD/SCID mice. Viremia was detected on days 5, 9, 13 and 17 and liver HBV DNA was detected on day 17 after injection. The serum and liver HBV DNA levels in LAM-resistant model carrying triple mutations are the highest among the models. Two NAs, LAM and entecavir (ETV), were used to test the availability of the models. LAM and ETV inhibited viral replication on wild-type model. LAM was no longer effective on LAM-resistant models, but ETV retains a strong activity. Therefore, these models can be used to evaluate anti-viral agents against lamivudine-resistance, affording new opportunities to establish other drug-resistant HBV small-animal models.Key words: Drug-resistance, Animal models, Hepatitis B virus, Hydrodynamic injection     

慢性乙型肝炎患者拉米夫定耐药模式及耐药后体内免疫环境的改变

目的探讨慢性乙型肝炎患者发生拉米夫定耐药常见的模式及耐药后体内免疫环境的改变。方法应用PCR及基因测序方法回顾性分析72例发生拉米夫定耐药患者血清HBVDNA多聚酶区基因变异模式,比较72例患者拉米夫定抗病毒6个月时及耐药后血清INF-γ、IL-2、IL-4因子水平与对照组细胞因子的水平差异。结果拉米夫定耐药4种主要的突变模式分别为：单位点rtM204I突变,占34.7%（25/72）;rtL180M＋rtM204V,占30.56%（22/72）;rtL180M＋rtM204I,占16.67%（12/72）;rtV173L＋rtV180M＋rtM204V,占12.5%（9/72）;抗病毒6个月时,未变异组与对照组IL-2（P=0.20）、IFN-γ（P=0.14）、IL-4（P=0.119）水平差异无统计学意义。耐药组HBVDNA发生病毒变异后,IL-2、IFN-γ水平显著低于对照组（P〈0.01）,而IL-4水平则高于对照组（P〈0.01）,差异有统计学意义。结论慢性乙型肝炎应用拉米夫定抗病毒治疗耐药模式主要是rtM204I突变及rtL180M、rtV173L、rtM204V、rtM204I联合变异,发生耐药后慢性乙型肝炎患者体内免疫环境将从Th1优势应答转换为Th2优势应答。     

拉米夫定耐药慢性乙型肝炎患者HBV多聚酶区基因突变分析

目的探讨拉米夫定（LAM）耐药慢性乙型肝炎（CHB）患者多聚酶区序列突变特点。方法收集63例接受拉米夫定治疗且耐药的CHB患者的临床资料,采用PCR产物直接测序法检测HBVP基因多聚酶区序列耐药变异。结果 63例诊断为耐药的患者中,51例患者检测到LAM相关的HBV多聚酶区基因突变,其中rtM204V/I变异46例（73.0%）,rtL180M变异25例（39.7%）,rtV173L/M变异5例（7.9%）,rtQ214E变异1例（1.6%）,rtS213T变异2例（2.%）12,rtV207L/M/I变异2例（3.2%）,rtA181T变异3例（4.8%）,rtT184I/S/M变异1例（1.6%）。结论对拉米夫定治疗患者的耐药检测除HBV多聚酶区常见的rtLl80M和rtM204V/I位点变异外,还应考虑其他位点的耐药变异。     

The main hepatitis B virus (HBV) mutants resistant to nucleoside analogs are susceptible in vitro to non-nucleoside inhibitors of HBV replication

Long-term treatment of chronic hepatitis B with nucleos(t)ide analogs can lead to the emergence of HBV resistant mutants of the polymerase gene. The development of drugs with a different mode of action is warranted to prevent antiviral drug resistance. Only a few non-nucleosidic molecules belonging to the family of phenylpropenamides (AT-61 & AT-130) and heteroaryldihydropyrimidines (BAY41-4109) can prevent RNA encapsidation or destabilize nucleocapsids, respectively. The sensitivity of the main nucleos(t)ide analog- resistant mutants to these inhibitors was evaluated in vitro. HepG2 stable cell lines permanently expressing wild type (WT) HBV or the main HBV mutants resistant to lamivudine and/or adefovir (rtL180M + rtM204V, rtV173L + rtL180M + rtM204V, rtM204I, rtL180M + rtM204I, rtN236T, rtA181V, rtA181V + rtN236T, rtA181T, rtA181T + rtN236T) were treated with AT-61, AT-130 or BAY-41 4109. Analysis of intracellular encapsidated viral DNA showed that all mutants were almost as sensitive to these molecules as WT HBV; indeed, the fold-resistance ranged between 0.7 and 2.3. Furthermore, the effect of a combination of either AT-61 or AT-130 with BAY41-4109, and the combination of these compounds with tenofovir was studied on wild type HBV as well as on a lamivudine and an adefovir-resistant mutant (rtL180M + M204V and rtN236T, respectively). These combinations of compounds resulted in inhibition of viral replication but showed slight antagonistic effects on the three HBV species. Based on this in vitro study, BAY-41 4109, AT-61 and AT-130 molecules that interfere with capsid morphogenesis are active against the main lamivudine- and adefovir-resistant mutants. These results suggest that targeting nucleocapsid functions may represent an interesting approach to the development of novel HBV inhibitors to prevent and combat drug resistance.     

核苷类药与慢性HBV感染者病毒P基因准种及变异特点的关系

目的观察核苷类药治疗不同时间段慢性HBV感染患者血清乙肝病毒聚合酶(HBV P)基因准种变化及变异特点。方法运用焦磷酸测序仪器配套的软件Assay Design SW在目的区域两端保守区域设计PCR引物及测序引物,采用套式PCR方法检测血清中HBV DNA,按照Pyro-Mark ID遗传分析系统用SNP模式进行PCR产物(HBV P基因相关位点)的焦磷酸测序和突变频率检测。108例慢性HBV感染患者中用药史明确者同期测定HBV DNA、HBV标志物、ALT。结果108例患者中,61例发生变异,变异模式以经典突变L180M、M204V/I、A181V/T、N236T突变为主,有少量V173L、S202G、T184G突变;其中40例用药史明确患者中,18例发生变异,发生变异者耐药突变型在样本中所占比例为20%-100%,HBV P基因变异可以在HBV DNA、ALT发生突变前、中、后检出。结论焦磷酸测序可以快速检测HBV P基因变异;变异株突变频率变化可初步反映HBVP基因准种异质性;HBV P基因变异模式、突变频率与核苷类药物敏感性密切相关。     

长期应用恩替卡韦治疗的慢性乙型肝炎患者耐药发生情况及原因分析:8年随访研究

目的:了解慢性乙型肝炎患者长期应用恩替卡韦(ETV)治疗的耐药发生情况并探讨耐药原因。方法:对2003-2007年3月参加ETV剂量和疗效的随机双盲Ⅱ期临床试验、ETV与拉米夫定(LAM)治疗慢性乙型肝炎的随机双盲对照Ⅲ期临床试验、ETV治疗LAM失效的慢性乙型肝炎Ⅲ期临床试验及其后续ETV开放治疗临床试验的63例慢性乙型肝炎患者继续给予治疗和随访,计算截至2011年3月的累积耐药发生率,对临床耐药患者进行乙型肝炎病毒(HBV)逆转录酶区(RT)序列突变检测,并分析耐药原因。结果:63例患者中3例治疗2年后失访;1例治疗2.5年时转其他中心治疗;其他59例中16例用药4～6年,43例用药7～8年,随访4～8年,中位随访时间7年。13例患者发生临床耐药,累积耐药发生率为20.5%。9例耐药患者进行了HBV RT序列突变检测,其中5例检测出LAM耐药位点L180M和M204V突变和1～2个ETV耐药位点突变,符合ETV耐药特点;3例仅检出LAM耐药位点突变;1例检出2个ETV耐药位点突变和ADF耐药位点A181T突变。LAM经治、治疗前高病毒载量、治疗6个月病毒学应答不佳、治疗依从性差可能与耐药的发生有关。结论:长期应用恩替卡韦治疗慢性乙型肝炎耐药率较低。对治疗初期应答不佳患者,加强监测和提高治疗依从性可减少耐药的发生。     

Mutations in the conserved woodchuck hepatitis virus polymerase FLLA and YMDD regions conferring resistance to lamivudine

During more than 104 weeks of treatment with lamivudine (3TC) in chronic woodchuck hepatitis virus (WHV) carrier woodchucks, viral recrudescence occurred. Analysis of WHV DNA polymerase from woodchuck serum samples by PCR followed by DNA sequencing demonstrated that all samples were wild type at the conserved YMDD motif in domain C. Four of the six 3TC-treated woodchucks showed a mixture of the wild-type Ala (GCT) and the mutant Thr (ACT) at the conserved amino acid residue 566 (FLLA) in domain B of the WHV polymerase region. The appearance of the A566T mutation was temporally associated with viral recrudescence. This change is analogous with the amino acid 181 (FLLA) in HBV where 3TC selects for a change from Ala to Thr in humans. In the woodchuck, the Ala to Thr change in the polymerase gene results in a mutation of the WHV surface protein (amino acid 377) from Trp (TGG) to an opal codon (TGA), which may prematurely terminates the polypeptide. Three WHV molecular infectious clones were constructed to study this mutation in greater detail in vitro: A566T, analogous to A181T in HBV; M589V, analogous to the M204V in HBV; and the double mutant A566T/M589V, analogous to A181T/M204V in HBV. These mutants exhibited drug-sensitivity and replication profiles that paralleled those reported for analogous HBV variants. In transfected Huh7 cells, WHV containing the M589V mutation conferred at least 100-fold increased resistance to 3TC, but replicated approximately 5-fold less efficiently than wild-type virus as judged by both extracellular virus production and intracellular DNA replicative forms. In contrast, A566T mutant was approximately 10-fold more resistant to 3TC, replicated intracellularly as well as wild type, but produced 10-fold lower levels of virions than wild type. These findings are consistent with the observation that the A566T mutation alters the overlapping WHV surface antigen reading frame. WHV carrying mutations in the conserved YMDD motif, while not directly selected during lamivudine therapy in WHV carrier woodchucks, are replication competent in cell culture indicating the potential for their emergence in treated animals. These results further illustrate the utility of the WHV/woodchuck model to studies of HBV-drug resistance.     

Sensitivity of L-(-)2,3-dideoxythiacytidine resistant hepatitis B virus to other antiviral nucleoside analogues.

L-(-)2',3'-Dideoxythiacytidine (L(-)SddC, Lamivudine) resistant hepatitis B virus (HBV) develops in patients after prolonged treatment. Point mutations detected in the viral genome from these patients have been shown to be responsible for L(-)SddC resistance. Therefore, new drugs active against L(-)SddC resistant HBV are needed. Using a transient transfection system, we studied the sensitivity of L(-)SddC resistant HBV to other anti-HBV nucleoside analogues. It was found that the L526M mutation alone caused greater resistance to penciclovir (PCV) than did the V553I mutation alone. Both mutations also caused the virus to be less sensitive to L(-)SddC and 2'-fluoro-5-methyl-beta-L-arabinofuranosyluracil (L-FMAU), although the degree of resistance was much less than that to PCV. The A546V mutation had no impact on the sensitivity to L(-)SddC, L-FMAU, and PCV. When these single mutations were coupled with the M550V/I mutation, all the double mutants were resistant to those drugs. Although 2',3'-dideoxy-2',3'-didehydro-beta-L(-)-5-fluorocytidine (L(-)Fd4C) was also less active, the IC50 of L(-)Fd4C against the L(-)SddC resistant mutant was at least fifty times lower than that against cell growth in culture. DNA polymerase associated with L(-)SddC resistant virions was also found to be less sensitive than that with wild-type HBV to those L-nucleoside triphosphates. All the L(-)SddC resistant mutants were still sensitive to 9-(2-phosphonylmethoxyethyl)-adenine (PMEA). These results suggest that different mutations in the HBV genome have a different impact on its sensitivity to those compounds, and L(-)SddC resistant HBV may also be resistant to PCV, L-FMAU, and L(-)Fd4C. A nucleoside analogue less toxic than PMEA could be developed against L(-)SddC resistant HBV.     

Inhibition of hepatitis B virus (HBV) replication by pyrimidines bearing an acyclic moiety: effect on wild-type and mutant HBV

Chronic hepatitis B virus (HBV) infection remains a major health problem worldwide. The main clinical limitation of a current antiviral drug for HBV, lamivudine, is the emergence of drug-resistant viral strains upon prolonged therapy. A group of 5-, 6-, or 5,6-substituted acyclic pyrimidine nucleosides with a 1-[(2-hydroxyethoxy)methyl] moiety were synthesized and evaluated for antiviral activities. The target compounds were prepared by the reaction of silylated uracils possessing a variety of substituents at the C-5 or C-6 positions or both with 1,3-dioxolane in the presence of potassium iodide and chlorotrimethylsilane by a convenient and single-step synthesis. Among the compounds tested, 5-chloro and 5-bromo analogues possessing an acyclic glycosyl moiety were the most effective and selective antiviral agents in the in vitro assays against wild-type duck HBV (EC50=0.4-2.2 and 3.7-18.5 microM, respectively) and human HBV-containing 2.2.15 cells (EC50=4.5-45.4 and 18.5-37.7 microM, respectively). These compounds were also found to retain sensitivity against lamivudine-resistant HBV containing a single mutation (M204I) and double mutations (L180M/M204V). The compounds investigated did not show cytotoxicity to host HepG2 and Vero cells, up to the highest concentration tested. The results presented here confirm and accentuate the potential of acyclic pyrimidine nucleosides as anti-HBV agents and extend our previous observations. We herein report the capability of acyclic pyrimidine nucleosides to inhibit the replication of both wild-type and drug-resistant mutant HBV.     

Understanding the molecular basis of HBV drug resistance by molecular modeling

Despite the significant successes in the area of anti-HBV agents, resistance and cross-resistance against available therapeutics are the major hurdles in drug discovery. The present investigation is to understand the molecular basis of drug resistance conferred by the B and C domain mutations of HBV-polymerase on the binding affinity of five anti-HBV agents [lamivudine (3TC, 1), adefovir (ADV, 2), entecavir (ETV, 3), telbivudine (LdT, 4) and clevudine (l-FMAU, 5)]. In this regard, homology modeled structure of HBV-polymerase was used for minimization, conformational search and induced fit docking followed by binding energy calculation on wild-type as well as on mutant HBV-polymerases (L180M, M204V, M204I, L180M + M204V, L180M − M204I). Our studies suggest a significant correlation between the fold resistances and the binding affinity of anti-HBV nucleosides. The binding mode studies reveals that the domain C residue M204 is closely associated with sugar/pseudosugar ring positioning in the active site. The positioning of oxathiolane ring of 3TC (1) is plausible due the induced fit orientation of the M204 residue in wild-type, and further mutation of M204 to V204 or I204 reduces the final binding affinity which leads to the drug resistance. The domain B residue L180 is not directly close (∼6 Å) to the nucleoside/nucleoside analogs, but indirectly associated with other active-site hydrophobic residues such as A87, F88, P177 and M204. These five hydrophobic residues can directly affect on the incoming nucleoside analogs in terms of its association and interaction that can alter the final binding affinity. There was no sugar ring shifting observed in the case of adefovir (2) and entecavir (3), and the position of sugar ring of 2 and 3 is found similar to the sugar position of natural substrate dATP and dGTP, respectively. The exocyclic double bond of entecavir (3) occupied in the backside hydrophobic pocket (made by residues A87, F88, P177, L180 and M204), which enhances the overall binding affinity. The active site binding of LdT (4) and l-FMAU (5) showed backward shifting along with upward movement without enforcing M204 residue and this significant different binding mode makes these molecules as polymerase inhibitors, without being incorporated into the growing HBV-DNA chain. Structural results conferred by these l- and d-nucleosides, explored the molecular basis of drug resistance which can be utilized for future anti-HBV drug discovery.     

Understanding the molecular basis of HBV drug resistance by molecular modeling

Despite the significant successes in the area of anti-HBV agents, resistance and cross-resistance against available therapeutics are the major hurdles in drug discovery. The present investigation is to understand the molecular basis of drug resistance conferred by the B and C domain mutations of HBV-polymerase on the binding affinity of five anti-HBV agents [lamivudine (3TC, 1), adefovir (ADV, 2), entecavir (ETV, 3), telbivudine (LdT, 4) and clevudine (l-FMAU, 5)]. In this regard, homology modeled structure of HBV-polymerase was used for minimization, conformational search and induced fit docking followed by binding energy calculation on wild-type as well as on mutant HBV-polymerases (L180M, M204V, M204I, L180M + M204V, L180M − M204I). Our studies suggest a significant correlation between the fold resistances and the binding affinity of anti-HBV nucleosides. The binding mode studies reveals that the domain C residue M204 is closely associated with sugar/pseudosugar ring positioning in the active site. The positioning of oxathiolane ring of 3TC (1) is plausible due the induced fit orientation of the M204 residue in wild-type, and further mutation of M204 to V204 or I204 reduces the final binding affinity which leads to the drug resistance. The domain B residue L180 is not directly close (6 Å) to the nucleoside/nucleoside analogs, but indirectly associated with other active-site hydrophobic residues such as A87, F88, P177 and M204. These five hydrophobic residues can directly affect on the incoming nucleoside analogs in terms of its association and interaction that can alter the final binding affinity. There was no sugar ring shifting observed in the case of adefovir (2) and entecavir (3), and the position of sugar ring of 2 and 3 is found similar to the sugar position of natural substrate dATP and dGTP, respectively. The exocyclic double bond of entecavir (3) occupied in the backside hydrophobic pocket (made by residues A87, F88, P177, L180 and M204), which enhances the overall binding affinity. The active site binding of LdT (4) and l-FMAU (5) showed backward shifting along with upward movement without enforcing M204 residue and this significant different binding mode makes these molecules as polymerase inhibitors, without being incorporated into the growing HBV-DNA chain. Structural results conferred by these l- and d-nucleosides, explored the molecular basis of drug resistance which can be utilized for future anti-HBV drug discovery.     

南京市乙肝病人乙型肝炎病毒P区突变特点与肝癌易感性的相关性分析

目的 探讨南京市乙肝病人乙型肝炎病毒（HBV）-P区突变特点与肝癌易感性的相关性。方法 选取2018年1月至2020年12月南京市第二医院乙肝病人1 100例，所有病人均采用聚合酶链反应（PCR）检测HBV基因分型及其P区突变位点情况，结合病理检查明确肝癌的发生情况，分析HBV-P区突变特点与肝癌易感性的相关性。结果 结合病理检查结果，纳入的1100例的乙肝病人中，肝癌发生率为2.18%(24/1 100)；肝癌组HBV-P区突变率高于乙肝组，差异有统计学意义（P<0.05）；进一步分析HBV-P区突变特点发现，肝癌组rt204、rt180、rt250位点突变率高于乙肝组，差异有统计学意义（P<0.05）;logistic回归分析结果显示，rt204、rt180、rt250位点突变是乙肝病人发生肝癌易感性的独立影响因素（P<0.05）。结论 南京市乙肝病人HBVP区突变特点与肝癌易感性有关，其中rt204、rt180、rt250位点突变可能易导致肝癌发生。     

Clinical evaluation of oligonucleotide microarrays for the detection of HBV mutants associated with lamivudine resistance

OBJECTIVES: Long-term lamivudine administration in hepatitis B virus (HBV)-infected patients induces the emergence of HBV mutants with lamivudine resistance. The aim of the present study was to evaluate the clinical application of an oligonucleotide microarray in detecting HBV mutants associated with lamivudine resistance. METHODS: 947 HBV DNA-positive sera from: 388 patients receiving lamivudine treatment, 559 chronic hepatitis B patients not receiving lamivudine treatment, and 359 from HBV DNA-negative controls, were assayed for HBV mutations using the oligonucleotide microarray. Furthermore, follow-up studies were performed using 255 clinical samples from 51 patients treated with lamivudine at various periods. The results were compared with sequencing and real-time polymerase chain reaction (PCR). RESULTS: The HBV DNA polymerase Tyr-Met-Asp-Asp motif (YMDD) mutation was detected in all 388 samples containing lamivudine-resistant mutations identified by microarray. For the codons rt180, rt204 and rt207, the agreements between the microarray and sequencing data are 96.6, 98.5 and 100%, respectively. Two previously unreported mutants were also found in those samples. In the 947 samples collected from different patients, which were detected positive for HBV DNA by quantitative PCR, all but three weak-positive samples were positive by the microarray, demonstrating an agreement of 99.7%. In all the positive samples, mutations could be detected in the relevant loci of HBV DNA polymerase with lamivudine resistance. All of the 359 HBsAg-negative samples were shown to be negative for HBV DNA using the microarray method. Follow-up detection of the clinical samples from 51 patients treated with lamivudine demonstrated that the microarray method was able to detect mutations in mixed viruses that were infecting prior to sequencing. CONCLUSION: The oligonucleotide microarray can be conveniently utilized to detect mutant HBV in clinical serum samples.     

Changes in different regions of hepatitis B virus gene in hepatitis B 'e' antigen-negative patients with chronic hepatitis B: the effect of long-term lamivudine therapy

BACKGROUND: Lamivudine therapy for chronic hepatitis B has been associated with changes in different regions of the hepatitis B virus nucleotide sequence. AIM: To study changes in the sequences of polymerase and precore/core promoter regions of hepatitis B virus, before and during 5 years of therapy with lamivudine. METHODS: Eighty consecutive samples were taken from 10 chronic hepatitis B 'e' antigen-negative patients. RESULTS: Nine patients carried hepatitis B virus precore mutations during the study. Before therapy, wild type was replaced by A1896 in two (20%) cases. During treatment, A1896 reverted transitory to wild type in five cases (50%) and in one case wild type was replaced by A1896. The continuous detection of precore mutations during therapy was associated with a lower response rate. YMDD mutations were observed in nine cases and both, L180M and M204V/I mutations were simultaneously detected in six cases. About 75% of the patients with M204V mutations were responders and none with M204I or mixed pattern sustained response. CONCLUSION: Hepatitis B 'e' antigen-negative patients exhibit changes in the precore regions both spontaneously and under lamivudine therapy, the transitory reversion to wild type being most frequently witnessed. Patients carrying M204V mutations are more likely to respond to therapy. If, in further studies, these results are confirmed some patients with YMDD mutations could benefit from prolonging the duration of lamivudine therapy.     

恩替卡韦抗乙型肝炎病毒感染量效关系及安全性的研究

目的:探讨恩替卡韦(ETV)治疗慢性乙型肝炎抗病毒感染的量效关系及安全性。方法:采用随机、双盲、安慰剂对照的临床试验,选择未经抗病毒治疗的慢性乙型肝炎病毒(HBV)感染者,按1:1:1的比例分为3组:ETV0.5mg/d组、ETV0.1mg/d组和安慰剂组,治疗28d,停药观察56d,然后用ETV0.5mg/d开放治疗48周,再次停药观察24周。结果:ETV0.5mg/d的疗效优于0.1mg/d,停药后HBV DNA的反跳也较缓慢。开放治疗期间有81.6%的受试者HBV DNA<0.7mmol/ml,HBeAg/抗HBe的血清转换率为7.9%,但停药后80%的受试者HBV DNA再度升高。给药组和安慰剂组受试者不良事件发生率无统计学差异(P=0.428),开放治疗期间未发现与恩替卡韦相关的严重不良反应。结论:ETV有较强的抗HBV活性,其抗病毒作用与剂量相关。恩替卡韦0.5mg/d治疗慢性乙型肝炎更为有效和安全。