乙型肝炎病毒基因C型:阿德福韦酯治疗过程中出现的耐药突变

StephenW

Hepatology International
June 2013, Volume 7, Issue 2, pp 443-450
Hepatitis B virus genotype C encoding resistance mutations that emerge during adefovir dipivoxil therapy: in vitro replication phenotype

    Wenpeng Li,
    Nadia Warner,
    Vitina Sozzi,
    Lilly Yuen,
    Danni Colledge,
    Tong Li,
    Hui Zhuang,
    Stephen Locarnini,
    Peter A. Revill


Abstract
Introduction

Hepatitis B virus (HBV) can be classified into ten genotypes (A–J), with genotypes B and C being the most common in Asia. Recent data suggest that the HBV genotype can influence disease progression, and genotype C has been associated with more aggressive liver disease than that of other genotypes. Although there is a preventative vaccine, chronic infection remains a public health problem with oral nucleos(t)ide analog therapy being the most common treatment. The HBV genome is composed of four partially overlapping reading frames, meaning that substitutions in the HBV polymerase selected during NA therapy may also alter the overlapping HBV surface antigen (HBsAg). We have recently shown that for HBV genotype D, the rtA181T/sW172stop substitution conferring resistance to adefovir dipivoxil (ADV) alters secretion of HBsAg and exerts a dominant-negative effect on wild-type virion secretion. However, the effect of this and other ADV-resistance-associated mutations on HBV replication and HBsAg secretion for the HBV genotype C, the genotype with the most severe clinical prognosis, is unknown.
Methods/Results

We constructed 1.2-mer infectious cDNA clones of HBV genotype C encoding mutations associated with ADV resistance and established an in vitro replication assay in Huh7 cells. Decreased levels of HBV DNA and HBsAg were detected for all ADV variants relative to the 1.2-mer wild-type polymerase control plasmid. Importantly, less HBsAg was detected in the cells transfected with the rtA181T resistance mutants, and the overlapping sW172stop mutation ablated secretion of HBsAg into cell culture supernatants.
Conclusions

The identification of secretion-defective HBV in the setting of ADV therapy for HBV genotype C, and to a lesser extent HBV genotype B, has major implications for the diagnosis and treatment of HBV in the Asia-Pacific region, as it is likely that quantitative HBsAg and viral load testing of serum from patients infected with HBV encoding rtA181T and rtN236T substitutions may not accurately reflect the level of replication within hepatocytes.

StephenW

乙型肝炎病毒（HBV）可分为10个基因型（A〜J），与B，C基因型是最常见的在亚洲。最近的数据表明，HBV基因型可影响疾病的进展，并一直伴随着更积极的肝脏疾病较其他基因型C基因型。虽然有一种预防性的疫苗，慢性感染与口服核苷（酸）IDE的模拟治疗是最常用的治疗仍是一个公共卫生问题。 HBV基因组是由四个部分重叠的读码框，也就是说在HBV聚合酶NA治疗过程中选择替换也可以改变重叠的乙肝病毒表面抗原（HBsAg）。最近，我们已经表明HBV基因型D，的替代rtA181T/sW172stop抗性阿德福韦酯（ADV）改变分泌HBsAg的发挥显性负效应，对野生型病毒颗粒的分泌。 ADV耐药相关基因突变对HBV复制和HBsAg分泌HBV C基因型，最严重的基因型与临床预后，但是，效果是未知的。
方法/结果

我们构建了1.2夏季感染性cDNA克隆HBV C基因型编码与ADV耐药相关基因突变，并建立了检测Huh7细胞在体外复制。被检测为所有ADV变种，相对1.2-MER野生型聚合酶控制质粒HBV DNA和HBsAg水平下降。重要的是，以下的HBsAg rtA181T抗性的突变体转染的细胞中检测到，和重叠的sW172stop突变烧蚀分泌到细胞培养上清液中的HBsAg。
结论

分泌缺陷的HBV的识别设置ADV治疗HBV C基因型，B基因型在较小程度上，具有重大的意义，因为它很可能在亚太地区的诊断和治疗HBV定量rtA181T与HBV编码和rtN236T换人感染患者血清HBsAg和病毒载量检测，可能无法准确反映在肝细胞内复制的水平。