Ou Guomin, He Lingyuan, Wang Luwei, Song Ji, Lai Xinyuan, Tian Xing, Wang Lei, Zhang Kai, Zhang Xuechao, Deng Juan, Zhuang Hui, Xiang Kuanhui, Li Tong
Department of Microbiology and Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China.
Department of Clinical Laboratory, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
Front Microbiol. 2021 Jul 9;12:687785. doi: 10.3389/fmicb.2021.687785. eCollection 2021.
Genetic variability has significant impacts on biological characteristics and pathogenicity of hepatitis B virus (HBV), in which the N-terminal sequence of the presurface 1 (preS1) region of HBV large surface protein (LHBs) displays genotype (GT) dependent genetic heterogeneity. However, the influence of this heterogeneity on its biological roles is largely unknown. By analyzing 6560 full-length genome sequences of GTA-GTH downloaded from HBVdb database, the preS1 N-terminal sequences were divided into four representative types, namely C-type (representative of GTA, GTB, and GTC), H-type (GTF and GTH), E-type (GTE and GTG), and D-type (GTD), respectively. We artificially substituted the preS1 N-termini of GTC and GTD plasmids or viral strains with each sequence of the four representative types. The roles of preS1 N-terminus on HBV replication, secretion and infectivity were investigated using HepG2 or HepG2-NTCP cells. In the transfection experiments, the results showed that the extracellular HBsAg levels and HBsAg secretion coefficients in D- and E-type strains were significantly higher than those in C- and H-type strains. D-type strain produced more extracellular HBV DNA than C-type strain. We further observed that D-, H-, and E-type strains increased the levels of intracellular replicative HBV DNAs, comparing with C-type strain. In the infection experiments, the levels of extracellular HBeAg, intracellular HBV total RNA and pgRNA/preC mRNA in D- and E-type strains were markedly higher than C and H-type ones. Our data suggest that the preS1 N-termini affect HBV replication, secretion and infectivity in a genotype dependent manner. The C- and H-type strains prefer to attenuate HBsAg secretion, while the strains of D- and E-type promoted infectivity. The existence and function of the intergenotypic shift of preS1 in naturally occurring recombination requires further investigation, as the data we acquired are mostly related to recombinant preS1 region between N-terminus of preS1 from genotypes A-H and the remaining preS1 portion of GTC or GTD.
基因变异性对乙型肝炎病毒(HBV)的生物学特性和致病性有重大影响,其中HBV大表面蛋白(LHBs)前S1(preS1)区域的N端序列表现出基因型(GT)依赖性遗传异质性。然而,这种异质性对其生物学作用的影响在很大程度上尚不清楚。通过分析从HBVdb数据库下载的6560条GTA - GTH全长基因组序列,将preS1 N端序列分为四种代表性类型,即C型(代表GTA、GTB和GTC)、H型(GTF和GTH)、E型(GTE和GTG)和D型(GTD)。我们用四种代表性类型的每个序列人工替换GTC和GTD质粒或病毒株的preS1 N端。使用HepG2或HepG2 - NTCP细胞研究preS1 N端对HBV复制、分泌和感染性的作用。在转染实验中,结果表明D型和E型菌株的细胞外HBsAg水平和HBsAg分泌系数显著高于C型和H型菌株。D型菌株产生的细胞外HBV DNA比C型菌株多。我们进一步观察到,与C型菌株相比,D型、H型和E型菌株增加了细胞内复制性HBV DNA的水平。在感染实验中,D型和E型菌株的细胞外HBeAg、细胞内HBV总RNA和pgRNA/preC mRNA水平明显高于C型和H型菌株。我们的数据表明,preS1 N端以基因型依赖性方式影响HBV复制、分泌和感染性。C型和H型菌株倾向于减弱HBsAg分泌,而D型和E型菌株促进感染性。由于我们获得的数据大多与基因型A - H的preS1 N端与GTC或GTD的其余preS1部分之间的重组preS1区域有关,因此天然重组中preS1基因型间转移的存在和功能需要进一步研究。