自然发生的5'preS1缺失显着增强HBV基因型B和基因型C的复制和

StephenW

Naturally occurring 5′ preS1 deletions markedly enhance replication and infectivity of HBV genotype B and genotype C
Abstract

Background and aims Deletion of 15-nucleotide or 18-nucleotide (nt) covering preS1 ATG frequently arises during chronic infection with HBV genotypes B and C. Since the second ATG is 33nt downstream, they truncate large (L) envelope protein by 11 residues like wild-type genotype D. This study characterised their functional consequences.

Methods HBV genomes with or without deletion were amplified from a patient with advanced liver fibrosis and assembled into replication competent 1.1mer construct. Deletion, insertion or point mutation was introduced to additional clones of different genotypes. Viral particles concentrated from transfected HepG2 cells were inoculated to sodium taurocholate cotransporting polypeptide (NTCP)-reconstituted HepG2 (HepG2/NTCP) cells or differentiated HepaRG cells, and HBV RNA, DNA, proteins were monitored.

Results From transfected HepG2 cells, the 15-nt and 18-nt deletions increased HBV RNA, replicative DNA and extracellular virions. When same number of viral particles was inoculated to HepG2/NTCP cells, the deletion mutants showed higher infectivity. Conversely, HBV infectivity was diminished by putting back the 18nt into naturally occurring genotype C deletion mutants and by adding 33nt to genotype D. Infectivity of full-length genotype C clones was also enhanced by mutating the first ATG codon of the preS1 region but diminished by mutating the second in-frame ATG. Removing N-terminal 11 residues from preS1 peptide 2–59 of genotype C potentiated inhibition of HBV infection and enhanced binding to HepG2/NTCP cells.

Conclusions The 15-nt and 18-nt deletions somehow increase HBV RNA, replicative DNA and virion production. Shortened L protein is more efficient at mediating HBV infection.
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http://dx.doi.org/10.1136/gutjnl-2019-320096

StephenW

自然发生的5'preS1缺失显着增强HBV基因型B和基因型C的复制和感染力
抽象

背景和目的覆盖preS1 ATG的15个核苷酸或18个核苷酸（nt）的缺失经常在HBV基因型B和C的慢性感染期间发生。由于第二个ATG位于下游33nt，因此它们通过11个残基将大的（L）包膜蛋白截短野生型基因型D。这项研究表征了它们的功能后果。

方法从晚期肝纤维化患者中扩增出有或无缺失的HBV基因组，并组装成具有复制能力的1.1mer构建体。缺失，插入或点突变被引入到不同基因型的其他克隆中。将转染的HepG2细胞浓缩的病毒颗粒接种到牛磺胆酸钠共转运多肽（NTCP）重构的HepG2（HepG2 / NTCP）细胞或分化的HepaRG细胞中，并监测HBV RNA，DNA，蛋白质。

结果从转染的HepG2细胞中，15-nt和18-nt缺失增加了HBV RNA，复制性DNA和细胞外病毒体。当相同数量的病毒颗粒接种到HepG2 / NTCP细胞中时，缺失突变体显示出更高的感染性。相反，通过将18nt放回天然存在的C型基因缺失突变体并在D型中添加33nt，可以降低HBV的感染性。全长C型克隆的感染性也可以通过使preS1区的第一个ATG密码子突变而得到增强，但通过改变第二个帧内ATG。从基因型C的preS1肽2–59中去除N末端的11个残基可增强对HBV感染的抑制作用，并增强与HepG2 / NTCP细胞的结合。

结论15-nt和18-nt缺失以某种方式增加了HBV RNA，复制性DNA和病毒体的产生。缩短的L蛋白在介导HBV感染方面更有效。
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http://dx.doi.org/10.1136/gutjnl-2019-320096