• HBV
• HCV
• HDV
• Viral hepatitis
• Yanomami

• Child
• Humans
• Adolescent
• Hepatitis B Surface Antigens
• Seroepidemiologic Studies
• Cross-Sectional Studies
• Hepatitis B/epidemiology
• Hepatitis B/diagnosis
• Hepatitis B Antibodies
• Hepatitis B virus
• Hepatitis, Viral, Human/epidemiology
• Hepatitis C Antibodies
• Prevalence
• Vaccines
• Hepatitis C/epidemiology

• ViroCap
• ViroMatch
• canine
• canine lobular orbital adenoma
• conjunctiva
• papillomavirus
• parvovirus
• virome

• VAF2017-01 ACVO Vision for Animals Foundation

Hepadnaviruses use extensively overlapping genes to expand their coding capacity, especially the precore/core genes encode the precore and core proteins with mostly identical sequences but distinct functions. The precore protein of the woodchuck hepatitis virus (WHV) is N-glycosylated, in contrast to the precore of the human hepatitis B virus (HBV) that lacks N-glycosylation. To explore the roles of the N-linked glycosylation sites in precore and core functions, we substituted T77 and T92 in the WHV precore/core N-glycosylation motifs (⁷⁵NIT⁷⁷ and ⁹⁰NDT⁹²) with the corresponding HBV residues (E77 and N92) to eliminate the sequons. Conversely, these N-glycosylation sequons were introduced into the HBV precore/core gene by E77T and N92T substitutions. We found that N-glycosylation increased the levels of secreted precore gene products from both HBV and WHV. However, the HBV core (HBc) protein carrying the E77T substitution was defective in supporting virion secretion, and during infection, the HBc E77T and N92T substitutions impaired the formation of the covalently closed circular DNA (cccDNA), the critical viral DNA molecule responsible for establishing and maintaining infection. In cross-species complementation assays, both HBc and WHV core (WHc) proteins supported all steps of intracellular replication of the heterologous virus while WHc, with or without the N-glycosylation sequons, failed to interact with HBV envelope proteins for virion secretion. Interestingly, WHc supported more efficiently intracellular cccDNA amplification than HBc in the context of either HBV or WHV. These findings reveal novel determinants of precore secretion and core functions and illustrate strong constraints during viral host adaptation resulting from their compact genome and extensive use of overlapping genes.

Hepadnaviruses infect a wide range of hosts. The human hepatitis B virus (HBV) and woodchuck hepatitis virus (WHV) are two closely related hepadnaviruses. In contrast to the WHV precore protein, which is N-glycosylated, the HBV precore protein lacks N-glycosylation. As precore and core proteins expressed from the overlapping precore/core genes share most of their sequences but have distinct functions, we investigated the roles of the N-linked glycosylation sequons in HBV and WHV precore/core genes. Our results revealed an important role of the N-linked glycosylation sequons in enhancing precore secretion levels and regulating core protein functions in virion secretion and infection. Furthermore, cross-species complementation assays using HBV and WHV core proteins and HBV or WHV genomes defective in core protein expression indicated that both HBV and WHV core proteins could support intracellular viral replication but not virion secretion of the heterologous virus. These results provide novel insights into the evolution of overlapping genes during host adaptation of hepadnaviruses.

• DNA, Circular
• DNA, Viral
• Genes, Overlapping
• Glycosylation
• Hepadnaviridae/genetics
• Hepatitis B/genetics
• Hepatitis B Virus, Woodchuck
• Hepatitis B virus/genetics
• Host Adaptation
• Humans
• Virus Replication/genetics

• R37 AI043453 NIAID NIH HHS
• National Institute of Arthritis and Musculoskeletal and Skin Diseases

Hepatitis B virus (HBV) has a highly restricted host range and cell tropism. Other than the human sodium taurocholate cotransporting polypeptide (huNTCP), the HBV entry receptor, host determinants of HBV susceptibility are poorly understood. Woodchucks are naturally infected with woodchuck hepatitis virus (WHV), closely related to HBV, but not with HBV. Here, we investigated the capabilities of woodchuck hepatic and human non-hepatic cell lines to support HBV infection. DNA transfection assays indicated that all cells tested supported both HBV and WHV replication steps post entry, including the viral covalently closed circular DNA (cccDNA) formation, which is essential for establishing and sustaining infection. Ectopic expression of huNTCP rendered one, but not the other, woodchuck hepatic cell line and the non-hepatic human cell line competent to support productive HBV entry, defined here by cccDNA formation during de novo infection. All huNTCP-expressing cell lines tested became susceptible to infection with hepatitis D virus (HDV) that shares the same entry receptor and initial steps of entry with HBV, suggesting that a late entry/trafficking step(s) of HBV infection was defective in one of the two woodchuck cell lines. In addition, the non-susceptible woodchuck hepatic cell line became susceptible to HBV after fusion with human hepatic cells, suggesting the lack of a host cell-dependent factor(s) in these cells. Comparative transcriptomic analysis of the two woodchuck cell lines revealed widespread differences in gene expression in multiple biological processes that may contribute to HBV infection. In conclusion, other than huNTCP, neither human- nor hepatocyte-specific factors are essential for productive HBV entry. Furthermore, a late trafficking step(s) during HBV infection, following the shared entry steps with HDV and before cccDNA formation, is subject to host cell regulation and thus, a host determinant of HBV infection.

Fundamental studies on, and development of therapies against, chronic hepatitis B virus (HBV) infection, which inflicts hundreds of millions worldwide, are impeded by deficiencies in HBV-susceptible animal models. HBV displays a strict species and cell tropism that are not clearly understood. Here, by studying replication of HBV, and the related woodchuck hepatitis virus, in human and woodchuck hepatic or non-hepatic cells, we found that non-hepatic human cells and some woodchuck hepatic cells could support productive HBV entry after expression of the human cell receptor for HBV. Moreover, by studying the infection of hepatitis D virus, which shares the same entry receptor and initial steps of entry with HBV, we could narrow down a host determinant of HBV infection operating at a late entry/trafficking step(s). Our study thus provides new insights into determinants of HBV host tropism and facilitates the development of HBV-susceptible animal models.

• Animals
• DNA, Circular/metabolism
• DNA, Viral/genetics
• DNA, Viral/metabolism
• Hepatitis B
• Hepatitis B Virus, Woodchuck
• Hepatitis B virus/metabolism
• Hepatitis Delta Virus/genetics
• Hepatitis Delta Virus/metabolism
• Hepatocytes
• Humans
• Marmota
• Virus Replication/genetics

• R37 AI043453 NIAID NIH HHS
• National Institute of Allergy and Infectious Diseases

• HDV-like viruses
• evolution
• helper virus
• origin

• Animals
• Evolution, Molecular
• Genome, Viral
• Helper Viruses/physiology
• Hepatitis D/virology
• Hepatitis Delta Virus/classification
• Hepatitis Delta Virus/genetics
• Hepatitis Delta Virus/physiology
• Host Specificity
• Humans
• Phylogeny
• Viral Proteins/genetics
• Viral Proteins/metabolism
• Virus Replication

This review describes woodchucks chronically infected with the woodchuck hepatitis virus (WHV) as an animal model for hepatocarcinogenesis and treatment of primary liver cancer or hepatocellular carcinoma (HCC) induced by the hepatitis B virus (HBV). Since laboratory animal models susceptible to HBV infection are limited, woodchucks experimentally infected with WHV, a hepatitis virus closely related to HBV, are increasingly used to enhance our understanding of virus-host interactions, immune response, and liver disease progression. A correlation of severe liver pathogenesis with high-level viral replication and deficient antiviral immunity has been established, which are present during chronic infection after WHV inoculation of neonatal woodchucks for modeling vertical HBV transmission in humans. HCC in chronic carrier woodchucks develops 17 to 36 mo after neonatal WHV infection and involves liver tumors that are comparable in size, morphology, and molecular gene signature to those of HBV-infected patients. Accordingly, woodchucks with WHV-induced liver tumors have been used for the improvement of imaging and ablation techniques of human HCC. In addition, drug efficacy studies in woodchucks with chronic WHV infection have revealed that prolonged treatment with nucleos(t)ide analogs, alone or in combination with other compounds, minimizes the risk of liver disease progression to HCC. More recently, woodchucks have been utilized in the delineation of mechanisms involved in innate and adaptive immune responses against WHV during acute, self-limited and chronic infections. Therapeutic interventions based on modulating the deficient host antiviral immunity have been explored in woodchucks for inducing functional cure in HBV-infected patients and for reducing or even delaying associated liver disease sequelae, including the onset of HCC. Therefore, woodchucks with chronic WHV infection constitute a well-characterized, fully immunocompetent animal model for HBV-induced liver cancer and for preclinical evaluation of the safety and efficacy of new modalities, which are based on chemo, gene, and immune therapy, for the prevention and treatment of HCC in patients for which current treatment options are dismal.

• Woodchuck
• Hepatitis B virus
• Chronic infection
• Liver disease
• Hepatocellular carcinoma
• Cancer treatment

• Proechimys semispinosus
• coinfection
• deltavirus
• hepadnavirus
• neotropical rodent

• cirrhosis
• hepatitis B virus
• hepatitis delta
• hepatocellular carcinoma

• HDV-host interactions
• Hepatitis delta virus
• Regulation of HDV infection outcome

• HBV life cycle
• chronic HBV infection
• hepatitis B virus
• integrant-derived viral RNAs

• Adult
• Base Sequence
• Carcinoma, Hepatocellular/virology
• Cells, Cultured
• DNA, Circular/genetics
• DNA, Viral/genetics
• Female
• Genome, Viral/genetics
• Hepatitis B Surface Antigens/genetics
• Hepatitis B virus/genetics
• Hepatitis B, Chronic/virology
• Humans
• Liver/virology
• Liver Neoplasms/virology
• Male
• Middle Aged
• RNA, Viral/genetics
• Sequence Analysis, RNA
• Viral Envelope Proteins/genetics
• Viral Load
• Virus Integration/genetics
• Virus Replication/genetics

• P20 GM104936 NIGMS NIH HHS
• R01 CA166213 NCI NIH HHS
• R21 AI099696 NIAID NIH HHS
• U54 HD090216 NICHD NIH HHS
• School of Medicine of the University of Kansas
• HHS | NIH | National Cancer Institute (NCI)
• HHS | NIH | National Institute of Allergy and Infectious Diseases (NIAID)

• Clinical aspects
• HDV
• Virology

• Animals
• Antiviral Agents/pharmacology
• Antiviral Agents/therapeutic use
• Biomarkers
• Carcinoma, Hepatocellular/etiology
• Coinfection
• Genome, Viral
• Genotype
• Hepatitis B
• Hepatitis D/diagnosis
• Hepatitis D/epidemiology
• Hepatitis D/therapy
• Hepatitis D/virology
• Hepatitis Delta Virus/classification
• Hepatitis Delta Virus/physiology
• Hepatitis Delta Virus/ultrastructure
• Humans
• Liver Cirrhosis/etiology
• Liver Neoplasms/etiology
• Prognosis
• RNA, Viral
• Superinfection
• Treatment Outcome
• Virus Replication

• Hepatitis B virus
• Hepatitis D virus
• Sodium taurocholate cotransporting polypeptide
• Viral entry
• Woodchuck

• Antiviral treatment
• Innate immune response
• Interferon-alpha
• Lamivudine
• Primary woodchuck hepatocytes
• Woodchuck hepatitis virus

• Chronic hepatitis
• Cirrhosis
• Hepatocellular carcinoma
• Viroids

Hepatitis delta virus (HDV) is the etiologic agent of the most severe form of virus hepatitis in humans. Sharing some structural and functional properties with plant viroids, the HDV RNA contains a single open reading frame coding for the only virus protein, the Delta antigen. A number of unique features, including ribozyme activity, RNA editing, rolling-circle RNA replication, and redirection for a RNA template of host DNA-dependent RNA polymerase II, make this small pathogen an excellent model to study virus-cell interactions and RNA biology. Treatment options for chronic hepatitis Delta are scarce and ineffective. The disease burden is perhaps largely underestimated making the search for new, specific drugs, targets, and treatment strategies an important public health challenge. In this review we address the main features of virus structure, replication, and interaction with the host. Virus pathogenicity and current treatment options are discussed in the light of recent developments.

• Hepatitis delta virus
• Hepatitis B virus
• RNA replication
• Pathogenesis
• Treatment

• R01 CA166213 NCI NIH HHS
• R21 AI097647 NIAID NIH HHS
• R21 AI099696 NIAID NIH HHS

• Acute WHV infection
• Hepadnavirus
• Replication markers
• WHV7
• WHVNY
• Woodchuck hepatitis virus strain

• Animals
• Antibodies, Viral/blood
• Female
• Hepatitis B/blood
• Hepatitis B/veterinary
• Hepatitis B/virology
• Hepatitis B Virus, Woodchuck/genetics
• Hepatitis B Virus, Woodchuck/physiology
• Male
• Marmota/virology
• Rodent Diseases/blood
• Rodent Diseases/virology
• Virus Replication

• P20 RR016443 NCRR NIH HHS
• R01 CA166213 NCI NIH HHS
• NCI R01CA166213 NCI NIH HHS
• NCRR P20RR016443 PHS HHS

• Cirrhosis
• Epigenetic processes
• Hepatitis D
• Hepatocellular carcinoma
• Necroinflammation
• Oxidative stress

Hepatitis delta virus (HDV) is a defective RNA virus that has an absolute requirement for a virus belonging to the hepadnaviridae family like hepatitis B virus (HBV) for its replication and formation of new virions. HDV infection is usually associated with a worsening of HBV-induced liver pathogenesis, which leads to more frequent cirrhosis, increased risk of hepatocellular carcinoma (HCC), and fulminant hepatitis. Importantly, no selective therapies are available for HDV infection. The mainstay of treatment for HDV infection is pegylated interferon alpha; however, response rates to this therapy are poor. A better knowledge of HDV–host cell interaction will help with the identification of novel therapeutic targets, which are urgently needed. Animal models like hepadnavirus-infected chimpanzees or the eastern woodchuck have been of great value for the characterization of HDV chronic infection. Recently, more practical animal models in which to perform a deeper study of host virus interactions and to evaluate new therapeutic strategies have been developed. Therefore, the main focus of this review is to discuss the current knowledge about HDV host interactions obtained from cell culture and animal models.

• Antrodia cinnamomea
• Hep 3B cells
• antcin K
• apoptosis
• autophagy

Human hepatitis B virus (HBV) infection and HBV-related diseases remain a major public health problem. Individuals coinfected with its satellite hepatitis D virus (HDV) have more severe disease. Cellular entry of both viruses is mediated by HBV envelope proteins. The pre-S1 domain of the large envelope protein is a key determinant for receptor(s) binding. However, the identity of the receptor(s) is unknown. Here, by using near zero distance photo-cross-linking and tandem affinity purification, we revealed that the receptor-binding region of pre-S1 specifically interacts with sodium taurocholate cotransporting polypeptide (NTCP), a multiple transmembrane transporter predominantly expressed in the liver. Silencing NTCP inhibited HBV and HDV infection, while exogenous NTCP expression rendered nonsusceptible hepatocarcinoma cells susceptible to these viral infections. Moreover, replacing amino acids 157–165 of nonfunctional monkey NTCP with the human counterpart conferred its ability in supporting both viral infections. Our results demonstrate that NTCP is a functional receptor for HBV and HDV.

DOI:http://dx.doi.org/10.7554/eLife.00049.001

Liver diseases related to the human hepatitis B virus (HBV) kill about 1 million people every year, and more than 350 million people around the world are infected with the virus. Some 15 million of these people are also infected with the hepatitis D virus (HDV), which is a satellite virus of HBV, and this places them at an even higher risk of liver diseases, including cancer. The viruses are known to enter liver cells by binding to receptors on their surface before being engulfed.

Both HBV and HDV have outer coats that consist of three kinds of envelope proteins, and a region called the pre-S1 domain in one of them is known to have a central role in the interaction between the viruses and the receptors and, therefore, in infecting the cells. However, the identity of the HBV receptor has remained a mystery. Now Yan et al. have identified this receptor to be sodium taurocholate cotransporting polypeptide. This protein, known as NTCP for short, is normally involved in the circulation of bile acids in the body.

In addition to humans, only two species are known to be susceptible to infection by human HBV and HDV—chimpanzees and a small mammal known as the treeshrew. Yan et al. started by isolating primary liver cells from treeshrews, and then used a combination of advanced purification and mass spectrometry analysis to show that the NTCP on the surface of the cells interacts with the pre-S1 domain in HBV.

The authors then performed a series of gene knockdown experiments on liver cells of both human and treeshrew origin: when the gene that codes for NTCP was silenced, HBV infection was greatly reduced. Moreover, they were able to transfect HepG2 cells—which are widely used in research into liver disease, but are not susceptible to HBV and HDV infection—with NTCP from humans and treeshrews to make them susceptible. Similarly, although monkeys are not susceptible to HBV, replacing just five amino acids in monkey NTCP with their human counterparts was enough to make the monkey NTCP a functional receptor for the viruses.

In the past, basic research into HBV and the development of antiviral therapeutics have both been hindered by the lack of suitable in vitro infection systems and animal models. Now, the work of Yan et al. means that it will be possible to use NTCP-complemented HepG2 cells for challenges as diverse as fundamental studies of basic viral entry/replication mechanisms and large-scale drug screening. It is also possible that HBV and HDV infection might interfere with some of the important physiological functions carried out by NTCP, so the latest work could also be of interest to medical scientists working on other diseases related to these infections.

DOI:http://dx.doi.org/10.7554/eLife.00049.002

• Other
• Sodium taurocholate cotransporting polypeptide
• Viruses
• hepatitis B virus
• hepatitis D virus
• liver
• receptor
• virus infection