Stem Cell-Derived Culture Models of Hepatitis E Virus Infection

Abstract

Similar to other hepatotropic viruses, hepatitis E virus (HEV) has been notoriously difficult to propagate in cell culture, limiting studies to unravel its biology. Recently, major advances have been made by passaging primary HEV isolates and selecting variants that replicate efficiently in carcinoma cells. These adaptations, however, can alter HEV biology. We have explored human embryonic or induced pluripotent stem cell (hESC/iPSC)-derived hepatocyte-like cells (HLCs) as an alternative to conventional hepatoma and hepatocyte cell culture systems for HEV studies. HLCs are permissive for nonadapted HEV isolate genotypes (gt)1-4 replication and can be readily genetically manipulated. HLCs, therefore, enable studies of pan-genotype HEV biology and will serve as a platform for testing anti-HEV treatments. Finally, we discuss how hepatocyte polarity is likely an important factor in the maturation and spread of infectious HEV particles.

Figure 1.

Stem cell culture models of hepatitis E virus (HEV) infection. Cells collected from identified HEV-positive individuals can be reprogrammed to generate induced pluripotent stem cells (iPSCs). Relevant single nucleotide polymorphisms (SNPs) can be repaired or introduced into established human embryonic or induced pluripotent stem cell (hESC)/iPSC lines using CRISPR-Cas9, followed by differentiation to the cell type of interest. Differentiated cells can be directly infected with HEV isolates from patients or animals for modeling virus–host interactions in a dish.

Figure 2.

Hepatocyte polarity and hepatitis E virus (HEV) secretion. HEV particle release from hepatocytes with (A) hepatic, (B) columnar, or (C) no polarity. Blue boxes in A and B are tight junctions separating apical and basal membranes.