Development of a hamster model for hepatitis B virus infection

PROJECT SUMMARY Hepatitis B virus (HBV) has infected more than one-third of the world’s population and that almost 296 million people are currently living with chronic infection including over 6 million children under the age of five. Each year, about 1.5 million people become newly infected and 820,000 people die from HBV infection and related

complications. Therapeutics for HBV are available, but they hardly lead to a functional cure for chronic HBV infection. One of the biggest challenges in developing an HBV cure is the lack of immunocompetent animal models that are susceptible to HBV infection and support the entire life cycle of HBV. HBV has an extremely

narrow host tropism, determined both by species-specific host cellular viral entry receptor, sodium taurocholate co-transporting peptide (NTCP), and the host factors needed to support the lifecycle of HBV post viral entry. HBV transgenic mice do not support the formation of viral covalently closed circular DNA (cccDNA), the bona

fide viral transcription template, via the intracellular cccDNA amplification mechanism; genetically modified mice carrying human NTCP fail to establish HBV infection due to the failure of de novo cccDNA formation. In search of other laboratory animal species-derived hepatocytes that may support HBV cccDNA formation, our preliminary

studies demonstrated that Ad-HBV-transduced primary hamster hepatocytes (PHaHs) are capable of supporting HBV DNA replication and cccDNA formation, and Ad-hNTCP-transduced PHaH cells are susceptible to HBV infection. Hence, the objective of this project is to establish a novel Syrian hamster (Mesocricetus auratus) model

that is tractable, fully immunocompetent, and highly susceptible for HBV infection. To this end, we will pursue the following Specific Aims: Aim 1. Establish a humanized-NTCP (huNTCP) hamster model for HBV infection. We will use the validated CRISPR-mediated gene editing techniques developed by us in the hamster

to humanize the two codons encoding the key amino acid residues in the hamster NTCP protein required for HBV infection. Aim 2. Establish acute and chronic infection in the huNTCP hamsters and characterize the pathogenesis and humoral immune responses to HBV. Under this Aim, we will infect huNTCP hamsters to

establish acute and chronic HBV infections and carry out pathogenesis studies. We will also carry out studies to characterize the humoral responses during acute and chronic infections. Aim 3. Test direct-acting antivirals (DAAs), immunoregulators and epigenetic modifiers in suppressing HBV infection in the huNTCP

hamster model. We will test the utility of this immunocompetent huNTCP hamster model in assessing the efficacies of a selected panel of anti-HBV drugs with different HBV-inhibiting mechanisms, including a direct acting antiviral (DAA), tenofovir (TDF), an immunoregulator, IFNalpahcon-1, and an epigenetic modifier, MS436,

in suppressing chronic HBV infection. We envision that this novel hamster model will greatly facilitate the development of new therapeutics that are needed to achieve a functional cure for HBV.