Department of Transfusion Medicine, School of Laboratory Medicine and Biotechnology, Southern Medical University, Guangzhou, China; Department of Laboratory Medicine, General Hospital of Southern Theatre Command of PLA, Guangzhou, China; Department of Clinical Laboratory, The First Affiliated Hospital of Shantou University Medical College, Shantou, China.
Department of Transfusion Medicine, School of Laboratory Medicine and Biotechnology, Southern Medical University, Guangzhou, China.
J Hepatol. 2021 Jun;74(6):1303-1314. doi: 10.1016/j.jhep.2020.12.023. Epub 2021 Jan 13.
BACKGROUND & AIMS: Occult HBV infection (OBI) is associated with transfusion-transmitted HBV infection and hepatocellular carcinoma. Studies on OBI genesis have concentrated on mutations in the S region and the regulatory elements. Herein, we aimed to determine the role of mutations in the core region on OBIs.
An OBI strain (SZA) carrying 9 amino acid (aa) substitutions in the core protein/capsid (Cp) was selected by sequence alignment and Western blot analysis from 26 genotype B OBI samples to extensively explore the impact of Cp mutations on viral antigen production in vitro and in vivo.
A large panel of 30 Cp replicons were generated by a replication-competent pHBV1.3 carrying SZA or wild-type (WT) Cp in a 1.3-fold over-length of HBV genome, in which the various Cp mutants were individually introduced by repairing site mutations of SZA-Cp or creating site mutations of WT-Cp by site-directed mutagenesis. The expression of HBcAg, HBeAg, and HBsAg and viral RNA was quantified from individual SZA and WT Cp mutant replicons in transfected Huh7 cells or infected mice, respectively. An analysis of the effect of Cp mutants on intracellular or extracellular viral protein production indicated that the W62R mutation in Cp had a critical impact on the reduction of HBcAg and HBeAg production during HBV replication, whereas P50H and/or S74G mutations played a limited role in influencing viral protein production invivo.
W62R and its combination mutations in HBV Cp might massively affect HBcAg and HBeAg production during viral replication, which, in turn, might contribute to the occurrence of OBI.
Occult hepatitis B virus infections (OBIs) have been found to be associated with amino acid mutations in the S region of the HBV, but the role of mutations in the core protein (Cp) remains unclear. In this study, an OBI strain (SZA) carrying 9 amino acid substitutions in Cp has been examined comprehensively in vitro and in vivo. The W62R mutation in Cp majorly reduces HBcAg and HBeAg production during HBV replication, potentially contributing to the occurrence of OBI.
隐匿性乙型肝炎病毒感染（OBI）与输血传播的乙型肝炎病毒感染和肝细胞癌有关。关于 OBI 发生机制的研究集中在 S 区和调节元件的突变上。在此，我们旨在确定核心区突变对 OBI 的作用。
通过序列比对和 Western blot 分析，从 26 例基因型 B OBI 样本中选择一株携带核心蛋白/衣壳（Cp）中 9 个氨基酸（aa）取代的 OBI 株（SZA），以广泛研究 Cp 突变对病毒抗原在体外和体内产生的影响。
通过复制能力强的 pHBV1.3 产生了一个包含 SZA 或野生型（WT）Cp 的大片段 30 个 Cp 复制子，在 HBV 基因组 1.3 倍的长度上，通过修复 SZA-Cp 的位点突变或通过定点诱变创建 WT-Cp 的位点突变，分别引入各种 Cp 突变体。分别从转染 Huh7 细胞的 SZA 和 WT Cp 突变复制子或感染的小鼠中定量检测 HBcAg、HBeAg 和 HBsAg 的表达和病毒 RNA。分析 Cp 突变对细胞内或细胞外病毒蛋白产生的影响表明，Cp 中的 W62R 突变对 HBV 复制过程中 HBcAg 和 HBeAg 产生的减少有重大影响，而 P50H 和/或 S74G 突变在体内影响病毒蛋白产生方面作用有限。
HBV Cp 中的 W62R 及其组合突变可能在病毒复制过程中大量影响 HBcAg 和 HBeAg 的产生，这反过来可能导致 OBI 的发生。
隐匿性乙型肝炎病毒感染（OBI）与乙型肝炎病毒（HBV）S 区的氨基酸突变有关，但核心蛋白（Cp）突变的作用尚不清楚。在这项研究中，对一株携带 Cp 中的 9 个氨基酸取代的 OBI 株进行了全面的体外和体内研究。Cp 中的 W62R 突变主要减少 HBV 复制过程中 HBcAg 和 HBeAg 的产生，可能导致 OBI 的发生。
