Mouse Models of Hepatitis B Virus Pathogenesis

Abstract

The host range of hepatitis B virus (HBV) is limited to humans and chimpanzees. As discussed in the literature, numerous studies in humans and chimpanzees have generated a great deal of information on the mechanisms that cause viral clearance, viral persistence, and disease pathogenesis during acute or chronic HBV infection. Relevant pathogenetic studies have also been performed in those few species representing natural hosts of hepadnaviruses that are related to HBV, such as the woodchuck hepatitis virus and the duck hepatitis virus. Further insight has been gained from multidisciplinary studies in transgenic or humanized chimeric mouse models expressing and/or replicating HBV to varying degrees. We provide here a concise summary of the available HBV mouse models as well as of the contributions of these models to our understanding of HBV pathogenesis.

Figure 1.

Mice created by microinjection of a terminally redundant viral DNA construct. (Top) Schematic representation of the construct that contains terminally redundant, greater than genome length (1.3 copies) of the complete hepatitis B virus (HBV) genome (ayw subtype) used to produce transgenic mouse lineages 1.3.32 and 1.3.46. The viral enhancers (En I and II) and the X (X), core (C), PreS (PS) and S promoters are indicated. (Left) Southern blot (SB) analysis of total hepatic DNA extracted from lineage 1.3.32 and hybridized with a 32P-labeled HBV-specific probe. Bands corresponding to the expected size of the integrated transgene, relaxed circular (rc), double-stranded linear (ds), and single-stranded (ss) HBV DNA are indicated. Northern blot (NB) analysis of total hepatic RNA extracted from lineage 1.3.32 and hybridized with a 32P-labeled HBV-specific probe. Bands corresponding to the expected size of the HBV 3.5- and 2.1-kb RNAs are indicated. (Right) Immunohistochemical analysis of a liver from lineage 1.3.32 shows that nuclear hepatitis B core antigen (HBcAg) is present in almost all of the hepatocytes, whereas cytoplasmic HBcAg is mainly detectable in centrilobular hepatocytes surrounding the central veins (immunoperoxidase stain for HBcAg; original magnification, 200×). (Inset) Electron microscopic analysis of hepatic nuclei and cytoplasm from lineage 1.3.32 revealed abundant 25- to 30-nm particles that were not present in nontransgenic controls (original magnification, 60,000×). (Bottom) The concentration of HBV virions in the serum of these animals is indicated. Poly A, Polypeptide A.

Figure 2.

Antiplatelet drugs can prevent hepatocarcinogenesis and greatly improve overall survival. (Top) Micrographs of representative histological liver preparations from the indicated groups of 107-5 mice at day 450 after the onset of immune-mediated chronic hepatitis. Sirius Red staining indicates the relative content of extracellular matrix deposition. Insets indicate areas that are shown below at higher magnification. Scale bars, 500 µm (insets); 100 µm (blown images). (Middle) Contrast-enhanced liver MRI scans of representative mice from the indicated groups at day 450 after the onset of immune-mediated chronic hepatitis are shown. Red arrows indicate hypointense regions identifying hepatocellular carcinomas (HCCs) after intravenous administration of the contrast agent gadoxetic acid (Primovist). (Bottom) Kaplan–Meier survival curves of the indicated groups of mice (20 mice/group). The statistical significance of differences between mice treated with placebo (diluents) or antiplatelet drugs (aspirin and clopidogrel) is indicated. (From Sitia et al. 2012; adapted, with permission, from the authors.)