Background & aims: HBV exhibits wide genetic diversity with at least 9 genotypes (GTs), which differ in terms of prevalence, geographic distribution, natural history, disease progression, and treatment outcome. However, differences in HBV replicative capacity, gene expression, and infective capability across different GTs remain incompletely understood. Herein, we aimed to study these crucial aspects using newly constructed infectious clones covering the major HBV GTs.
Methods: The replicative capacity of infectious clones covering HBV GTs A-E was analyzed in cell lines, primary hepatocytes and humanized mice. Host responses and histopathology induced by the different HBV GTs were characterized in hydrodynamically injected mice. Differences in treatment responses to entecavir and various HBV capsid inhibitors were also quantified across the different genetically defined GTs.
Results: Patient-derived HBV infectious clones replicated robustly both in vitro and in vivo. GTs A and D induce more pronounced intrahepatic and proinflammatory cytokine responses which correlated with faster viral clearance. Notably, all 5 HBV clones robustly produced viral particles following transfection into HepG2 cells, and these particles were infectious in HepG2-NTCP cells, primary human hepatocytes and human chimeric mice. Notably, GT D virus exhibited higher infectivity than GTs A, B, C and E in vitro, although it was comparable to GT A and B in the human liver chimeric mice in vivo. HBV capsid inhibitors were more readily capable of suppressing HBV GTs A, B, D and E than C.
Conclusions: The infectious clones described here have broad utility as genetic tools that can mechanistically dissect intergenotypic differences in antiviral immunity and pathogenesis and aid in HBV drug development and screening.
Lay summary: The hepatitis B virus (HBV) is a major contributor to human morbidity and mortality. HBV can be categorized into a number of genotypes, based on their specific genetic make-up, of which 9 are well known. We isolated and cloned the genomes of 5 of these genotypes and used them to create valuable tools for future research on this clinically important virus.
Keywords: AAV, adeno-associated virus; ALT, alanine aminotransferase; BCP, basic core promoter; CHB, chronic hepatitis B; CpAM, core protein allosteric modulators; DR, direct repeat; ETV, entecavir; En, enhancer; GT(s), genotype(s); HBV, hepatitis B virus; HBVcc, cell culture-derived HBV; HCC, hepatocellular carcinoma; HDI, hydrodynamic injection; IFN, interferon; IHC, immunohistochemistry; IL, interleukin; MOI, multiplicity of infection; NA, nucleos(t)ide analogue; NRG, NODRag1−/−IL2RγNULL; PHH, primiary human hepatocyte; SVR, sustained virologic response; cccDNA, covalently closed circular DNA; dpi, days post infection; drug development; genotypes; hepatitis B; hepatitis B virus; host responses; pgRNA, pre-genomic RNA; reverse genetics; viral hepatitis.
© 2022 The Authors.