Identification of a pre-S2 mutant in hepatocytes expressing a novel marginal pattern of surface antigen in advanced diseases of chronic hepatitis B virus infection
Identification of a pre-S2 mutant in hepatocytes expressing a novel marginal pattern of surface antigen in advanced diseases of chronic hepatitis B virus infection
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DOI：
10.1046/j.1440-1746.2000.02187.x
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发表时间：
2000-05-01
影响因子：
4.1
通讯作者：
Su, IJ
中科院分区：
文献类型：
--
作者：
Fan, YF;Lu, CC;Su, IJ
背景与目的：肝组织中B型肝炎病毒（HBV）抗原的表达反映了慢性HBV感染的复制状态。我们以前已经认识到肝细胞中B型肝炎表面抗原（HBsAg）的一种新的边缘模式，它通常成组聚集并在晚期非复制期出现。本研究的目的是调查是否边缘型HBsAg代表一个特定的HBV-表面mutant.Methods的基因产物：显微解剖的结节均匀表达边缘HBsAg进行了两个12例切除的肝脏从HBsAg血清阳性的肝癌患者。推测编码边缘HBsAg的基因被聚合酶链反应（PCR）克隆、测序和分析。在体外转染和表达的克隆表面突变体质粒上的Huh 7细胞系，以说明肝内HBsAg expression.Results：免疫组化染色显示，边缘HBsAg是前S1阳性，因此包含大的表面蛋白。PCR克隆和测序表明，两种情况下的边缘型HBsAg编码基因在前S2的5'端（nt 2-55）有相同的缺失。在1例病例中还发现了小表面（S）抗原的点突变。前S2缺失序列和S基因的突变位点与人淋巴细胞抗原限制性T和/或B细胞表位一致。在体外转染的突变体质粒揭示了一个斑点状的保留或积累的HBsAg在细胞质中或在肝细胞的外周，伴随着减少分泌的HBsAg在培养上清液中，模仿intrahepatic expression.Conclusion：一个自然的前S2缺失突变体被确定在肝细胞中表达一种新的边缘模式的HBsAg，它可能包含突变，大，表面蛋白。鉴于表达边缘HBsAg的肝细胞的聚集性增殖，前S2缺失突变体的生物学意义应该是有趣的。(C)2000 Blackwell Science Asia Pty Ltd.
Background and Aims: The expression of hepatitis B viral (HBV) antigens in liver tissue reflects the replicative status of chronic HBV infection. We have previously recognized a novel marginal pattern of hepatitis B surface antigen (HBsAg) in hepatocytes, which usually clusters in groups and emerges at the late non-replicative phase. This study was designed to investigate whether the marginal-type HBsAg represented the gene product of a specific HBV-surface mutant.Methods: Microdissection of cirrhotic nodules homogeneously expressing marginal HBsAg was performed on two of 12 resected livers from HBsAg-seropositive patients with hepatocellular carcinoma. The gene presumably encoding marginal HBsAg was polymerase chain reaction (PCR)-cloned, sequenced and analysed. In vitro transfection and expression of the cloned surface mutant plasmids were performed on the Huh7 cell line to illustrate intrahepatic HBsAg expression.Results: Immunohistochemical staining revealed that the marginal HBsAg was positive for pre-S1 and thus contained large surface proteins. The PCR cloning and sequencing of the genes presumably encoding marginal-type HBsAg in both cases revealed the same deletion at the 5' terminus (nt 2-55) of pre-S2. A point mutation on the small-surface (S) antigen was also found in one case. The pre-S2 deletion sequence and the mutation sites of the S gene coincide with human lymphocyte antigen-restricted T- and/or B-cell epitopes. In vitro transfection of the mutant plasmid revealed a blot-like retention or accumulation of HBsAg in the cytoplasm or at the periphery of hepatocytes, accompanied by a decreased secretion of HBsAg in the culture supernatant, mimicking intrahepatic expression.Conclusion: A natural pre-S2 deletion mutant was identified in hepatocytes expressing a novel marginal pattern of HBsAg, which probably contains mutant, large, surface proteins. The biological significance of the pre-S2 deletion mutant should be interesting in view of the clustering proliferation of hepatocytes expressing marginal HBsAg. (C) 2000 Blackwell Science Asia Pty Ltd.