Cátedra de Virología, Departamento de Microbiología, Inmunología, Biotecnología y Genética, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, Buenos Aires 1113, Argentina.
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires 1425, Argentina.
Viruses. 2019 Jul 18;11(7):655. doi: 10.3390/v11070655.
Hepatitis B virus (HBV) is classified into ten genotypes and numerous subgenotypes (sgt). In particular, sgt F1b and sgt F4, native of Latin America, have been associated with differences in clinical and virological characteristics. Hepatitis B virus X protein (HBx) is a multifunctional regulatory protein associated with the modulation of viral transcription and replication. In this work, we analyzed the role of the X gene and the encoded X protein in sgtF1b and sgtF4 replication. Transfection with HBx deficient genomes revealed remarkable differences in the replicative capacity of sgtF1b and sgtF4 mutants. The silencing of HBx increased sgtF1b X(-) transcription and replication by more than 2.5 fold compared to the wild type variant, while it decreased sgtF4 X(-) transcription and replication by more than 3 fold. Trans-complementation of HBx restore sgtF1b and sgtF4 wild type transcription and replication levels. In addition, transfection with chimeric variants, carrying wild type (F1b/XF4 and F4/XF1b) or mutated (F1b/X(-)F4 and F4/X(-)F1b) X gene of one sgt in the backbone of the other sgt, showed that the nucleotide sequence of the X gene, that includes regulatory elements that modulate pgRNA transcription, was responsible for the disparity observed between sgtF1b X(-) and sgtF4 X(-). These results showed that sgtF1b and sgtF4 X gene play a central role in regulating HBV transcription and replication, which eventually lead to a common purpose, to reach wild type replication levels of sgtF1b and sgtF4 viruses.
乙型肝炎病毒 (HBV) 分为十个基因型和许多亚型 (sgt)。特别是，起源于拉丁美洲的 sgtF1b 和 sgtF4 与临床和病毒学特征的差异有关。乙型肝炎病毒 X 蛋白 (HBx) 是一种多功能调节蛋白，与病毒转录和复制的调节有关。在这项工作中，我们分析了 X 基因和编码的 X 蛋白在 sgtF1b 和 sgtF4 复制中的作用。用 HBx 缺失基因组转染显示，sgtF1b 和 sgtF4 突变体的复制能力有显著差异。与野生型变异体相比，HBx 的沉默使 sgtF1b X(-)转录和复制增加了 2.5 倍以上，而使 sgtF4 X(-)转录和复制增加了 3 倍以上。HBx 的转互补恢复了 sgtF1b 和 sgtF4 野生型转录和复制水平。此外，用携带野生型 (F1b/XF4 和 F4/XF1b) 或突变型 (F1b/X(-)F4 和 F4/X(-)F1b) X 基因的嵌合变体转染，表明 X 基因的核苷酸序列，包括调节 pgRNA 转录的调节元件，是导致 sgtF1b X(-)和 sgtF4 X(-)之间观察到的差异的原因。这些结果表明，sgtF1b 和 sgtF4 X 基因在调节 HBV 转录和复制中起着核心作用，最终达到 sgtF1b 和 sgtF4 病毒的野生型复制水平的共同目的。
