Hepatitis B Virus Infection Model Research Articles

The feasibility of establishing a hamster model for HBV infection: in vitro evidence.

Chronic hepatitis B virus (HBV) infection remains a significant public health burden with no cure currently available. The research to cure HBV has long been hampered by the lack of immunocompetent small animal models capable of supporting HBV infection. Here, we set out to explore the feasibility of the golden Syrian hamster as an immunocompetent small rodent model for HBV infection. We first started with in vitro assessments of the HBV replication cycle in primary hamster hepatocytes (PHaHs) by adenoviral HBV (Ad-HBV) transduction. Our results demonstrated that PHaHs support HBV reverse transcription and subsequent cccDNA formation via the intracellular recycling pathway. Next, with luciferase reporter assays, we confirmed that PHaHs support the activities of all HBV major promoters. Then, we transduced PHaHs with an adenoviral vector expressing HBV receptor human Na+/taurocholate cotransporting polypeptide NTCP (Ad-huNTCP), followed by HBV inoculation. While the untransduced PHaHs did not support HBV infection, Ad-huNTCP-transduced PHaHs supported de novo cccDNA formation, viral mRNA transcription, and expression of viral antigens. We then humanized the amino acid (aa) residues of hamster NTCP (haNTCP) critical for HBV entry, aa84-87 and aa157-165, and transfected HepG2 cells with constructs expressing wild-type haNTCP and humanized-haNTCP, H84R/P87N and H84R/P87N/G157K/M160V/M165L, respectively, followed by HBV inoculation. The results showed that the humanization of H84R/P87N alone was sufficient to support HBV infection at a level comparable to that supported by huNTCP. Taken together, the above in vitro evidence supports the future direction of humanizing haNTCP for HBV infection in vivo.IMPORTANCEOne of the biggest challenges in developing an HBV cure is the lack of immunocompetent animal models susceptible to HBV infection. Developing such models in mice has been unsuccessful due to the absence of a functional HBV receptor, human NTCP (huNTCP), and the defect in supporting viral cccDNA formation. In search of alternative models, we report herein multiple lines of in vitro evidence for developing a golden Syrian hamster model for HBV infection. We demonstrate that the primary hamster hepatocytes (PHaHs) support HBV replication, transcription, and cccDNA formation, and PHaHs are susceptible to de novo HBV infection in the presence of huNTCP. Furthermore, expressing hamster NTCP with two humanized residues critical for HBV entry renders HepG2 cells permissive to HBV infection. Thus, our work lays a solid foundation for establishing a gene-edited hamster model that expresses humanized NTCP for HBV infection in vivo.

A therapeutic HBV vaccine containing a checkpoint modifier enhances CD8+ T cell and antiviral responses.

In patients who progress from acute hepatitis B virus (HBV) infection to a chronic HBV (CHB) infection, CD8+ T cells fail to eliminate the virus and become impaired. A functional cure of CHB likely requires CD8+ T cell responses different from those induced by the infection. Here we report preclinical immunogenicity and efficacy of an HBV therapeutic vaccine that includes herpes simplex virus (HSV) glycoprotein D (gD), a checkpoint modifier of early T cell activation, that augments CD8+ T cell responses. The vaccine is based on a chimpanzee adenovirus serotype 6 (AdC6) vector, called AdC6-gDHBV2, which targets conserved and highly immunogenic regions of the viral polymerase and core antigens fused to HSV gD. The vaccine was tested with and without gD in mice for immunogenicity, and in an AAV8-1.3HBV vector model of antiviral efficacy. The vaccine encoding the HBV antigens within gD stimulates potent and broad CD8+ T cell responses. In a surrogate model of HBV infection, a single intramuscular injection achieved pronounced and sustained declines of circulating HBV DNA copies and HBV surface antigen; both inversely correlated with HBV-specific CD8+ T cell frequencies in spleen and liver.

Hepatitis B Virus Increases SphK1-S1P Synthesis by Promoting the Availability of the Transcription Factor USF1.

Hepatitis B virus (HBV) is the most common chronic viral infection globally, affecting ∼360 million people and causing about 1 million deaths annually due to end-stage liver disease or hepatocellular carcinoma. Current antiviral treatments rarely achieve a functional cure for chronic hepatitis B, highlighting the need for improved monitoring and intervention strategies. This study explores the role of the sphingosine kinase 1 (SphK1)-sphingosine-1-phosphate (S1P) axis in HBV-related liver injury. We investigated the association between serum S1P concentration and HBV DNA levels in chronic hepatitis B patients, finding a significant positive correlation. Additionally, SphK1 was elevated in liver tissues of HBV-positive hepatocellular carcinoma patients, particularly in HBsAg-positive regions. HBV infection models in HepG2-sodium taurocholate cotransporting polypeptide cells confirmed that HBV enhances SphK1 expression and S1P production. Inhibition of HBV replication through antiviral agents and the CRISPR-Cas9 system reduced SphK1 and S1P levels. Further, we identified the transcription factor USF1 as a key regulator of SphK1 expression during HBV infection. USF1 binds to the SphK1 promoter, increasing its transcriptional activity, and is upregulated in response to HBV infection. In vivo studies in mice demonstrated that HBV exposure promotes the expression of USF1 and SphK1-S1P. These findings suggest that the SphK1-S1P axis, regulated by HBV-induced USF1, could serve as a potential biomarker and therapeutic target for HBV-related liver injury.

Lipid nanoparticle-encapsulated DOCK11-siRNA efficiently reduces hepatitis B virus cccDNA level in infected mice

The hepatitis B virus (HBV) infects many people worldwide. As HBV infection frequently leads to liver fibrosis and carcinogenesis, developing anti-HBV therapeutic drugs is urgent. Therapeutic drugs for preventing covalently closed circular DNA (cccDNA) production, which can eliminate HBV infection, are unavailable. The host factor dedicator of cytokinesis 11 (DOCK11) is involved in the synthesis and maintenance of HBV cccDNA in vitro. However, the effectiveness of DOCK11 as a target for the in vivo elimination of HBV cccDNA remains unclear. In this study, we assessed whether DOCK11 inhibitors suppressed HBV cccDNA production in mouse models of HBV infection. The tocopherol-conjugate hetero gapmer, a DNA/RNA duplex of gapmer/complementary RNA targeting the DOCK11 sequence, partially reduced the expression of DOCK11 but not that of HBV cccDNA, in the livers of HBV-infected human hepatocyte chimeric mice, along with weight loss and decreased serum human albumin levels. Lipid nanoparticle-encapsulated chemically modified siRNAs specific for DOCK11 suppressed DOCK11 expression and decreased HBV cccDNA levels without adverse effects in the mice. Therefore, nucleic acid-based drugs targeting DOCK11 in hepatocytes are potentially effective anti-HBV therapeutics, which can reduce HBV cccDNA levels in vivo.

CRISPR-Cas13b-mediated suppression of HBV replication and protein expression

New antiviral approaches that target multiple aspects of the HBV replication cycle to improve rates of functional cure are urgently required. HBV RNA represents a novel therapeutic target. Here, we programmed CRISPR-Cas13b endonuclease to specifically target the HBV pregenomic RNA and viral mRNAs in a novel approach to reduce HBV replication and protein expression. Cas13b CRISPR RNAs (crRNAs) were designed to target multiple regions of HBV pregenomic RNA. Mammalian cells transfected with replication competent wild-type HBV DNA of different genotypes, a HBV-expressing stable cell line, a HBV infection model and a hepatitis B surface antigen (HBsAg)-expressing stable cell line were transfected with PspCas13b-BFP (blue fluorescent protein) and crRNA plasmids, and the impact on HBV replication and protein expression was measured. Wild-type HBV DNA, PspCas13b-BFP and crRNA plasmids were simultaneously hydrodynamically injected into mice, and serum HBsAg was measured. PspCas13b mRNA and crRNA were also delivered to a HBsAg-expressing stable cell line via lipid nanoparticles and the impact on secreted HBsAg determined. Our HBV-targeting crRNAs strongly suppressed HBV replication and protein expression in mammalian cells by up to 96% (p <0.0001). HBV protein expression was also reduced in a HBV-expressing stable cell line and in the HBV infection model. CRISPR-Cas13b crRNAs reduced HBsAg expression by 50% (p <0.0001) invivo. Lipid nanoparticle-encapsulated PspCas13b mRNA reduced secreted HBsAg by 87% (p= 0.0168) in a HBsAg-expressing stable cell line. Together, these results show that CRISPR-Cas13b can be programmed to specifically target and degrade HBV RNAs to reduce HBV replication and protein expression, demonstrating its potential as a novel therapeutic option for chronic HBV infection. Owing to the limitations of current antiviral therapies for hepatitis B, there is an urgent need for new treatments that target multiple aspects of the HBV replication cycle to improve rates of functional cure. Here, we present CRISPR-Cas13b as a novel strategy to target HBV replication and protein expression, paving the way for its development as a potential new treatment option for patients living with chronic hepatitis B.

CARs derived from broadly neutralizing, human monoclonal antibodies identified by single B cell sorting target hepatitis B virus-positive cells.

To design new CARs targeting hepatitis B virus (HBV), we isolated human monoclonal antibodies recognizing the HBV envelope proteins from single B cells of a patient with a resolved infection. HBV-specific memory B cells were isolated by incubating peripheral blood mononuclear cells with biotinylated hepatitis B surface antigen (HBsAg), followed by single-cell flow cytometry-based sorting of live, CD19+ IgG+ HBsAg+ cells. Amplification and sequencing of immunoglobulin genes from single memory B cells identified variable heavy and light chain sequences. Corresponding immunoglobulin chains were cloned into IgG1 expression vectors and expressed in mammalian cells. Two antibodies named 4D06 and 4D08 were found to be highly specific for HBsAg, recognized a conformational and a linear epitope, respectively, and showed broad reactivity and neutralization capacity against all major HBV genotypes. 4D06 and 4D08 variable chain fragments were cloned into a 2nd generation CAR format with CD28 and CD3zeta intracellular signaling domains. The new CAR constructs displayed a high functional avidity when expressed on primary human T cells. CAR-grafted T cells proved to be polyfunctional regarding cytokine secretion and killed HBV-positive target cells. Interestingly, background activation of the 4D08-CAR recognizing a linear instead of a conformational epitope was consistently low. In a preclinical model of chronic HBV infection, murine T cells grafted with the 4D06 and the 4D08 CAR showed on target activity indicated by a transient increase in serum transaminases, and a lower number of HBV-positive hepatocytes in the mice treated. This study demonstrates an efficient and fast approach to identifying pathogen-specific monoclonal human antibodies from small donor cell numbers for the subsequent generation of new CARs.

Mathematical Models of Early Hepatitis B Virus Dynamics in Humanized Mice

Analyzing the impact of the adaptive immune response during acute hepatitis B virus (HBV) infection is essential for understanding disease progression and control. Here we developed mathematical models of HBV infection which either lack terms for adaptive immune responses, or assume adaptive immune responses in the form of cytolytic immune killing, non-cytolytic immune cure, or non-cytolytic-mediated block of viral production. We validated the model that does not include immune responses against temporal serum hepatitis B DNA (sHBV) and temporal serum hepatitis B surface-antigen (HBsAg) experimental data from mice engrafted with human hepatocytes (HEP). Moreover, we validated the immune models against sHBV and HBsAg experimental data from mice engrafted with HEP and human immune system (HEP/HIS). As expected, the model that does not include adaptive immune responses matches the observed high sHBV and HBsAg concentrations in all HEP mice. By contrast, while all immune response models predict reduction in sHBV and HBsAg concentrations in HEP/HIS mice, the Akaike Information Criterion cannot discriminate between non-cytolytic cure (resulting in a class of cells refractory to reinfection) and antiviral block functions (of up to 99%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$99\\%$$\\end{document} viral production 1–3 weeks following peak viral load). We can, however, reject cytolytic killing, as it can only match the sHBV and HBsAg data when we predict unrealistic levels of hepatocyte loss.

The downregulation of Tapasin in dendritic cell regulates CD8+ T cell autophagy to hamper hepatitis B viral clearance in the induced pluripotent stem cell-derived hepatocyte organoid.

Tapasin, a crucial molecular chaperone involved viral antigen processing and presentation, plays an important role in antivirus immunity. However, its impact on T cell differentiation in the context of virus clearance remains unclear. In this study, we employed induced pluripotent stem cellsto differentiate into hepatocyte-like cell,which were subsequently inserted to the inverted colloidal crystalscaffolds, thus establishing a hepatocyte organoid (HO). By inoculating hepatitis B virus (HBV) particles in the system, we successfully engineered a robust in vitro HBV infection model for at least 3 weeks. Furthermore, we aimed to explore the effects of lentivirus-mediated short hairpin RNA (shRNA) targeting human Tapasin on the differentiation and antiviral function of CD8+ T cells. Specifically, we transfected dendritic cells (DCs) with Tapasin-shRNA and cocultured with T cells. The results demonstrated that Tapasin-shRNA transfected DCs effectively suppressed T cell proliferation and impeded HBV-specific cytotoxic T lymphocyte responses. Our investigation also revealed the role of mTOR pathway activation in reducing autophagy activity within CD8+ T cells. Expressions of autophagy-related proteins, beclin-1, LC3II/LC3I were decreased and PI3K/AKT/mTOR activity was increased in Tapasin-shRNA group. Collectively, our findings elucidate that shRNA targeting the Tapasin gene within DCs inhibits T cell differentiation by reducing autophagy activity to hamper viral clearance in the HBV-infected HO.

Accumulated experience and future prospects of &lt;i&gt;in vivo&lt;/i&gt; hepatitis B virus research

Nowadays, an estimated more than 300 million people live with hepatitis B virus (HBV) infection globally. One of the main goals of the World Health Organization (WHO) is to eliminate viral hepatitis by the year 2030. The study of the pathogenic and immunologic properties of HBV, as well as therapeutic substances and treatment regimens, is significantly complicated by the insufficient number of susceptible biological test subjects (animal models) and the lack of zoonotic reservoirs of the virus. In this regard, researching the properties of HBV and related hepadnaviruses provides invaluable material for understanding the biology of the pathogen and the developing methods of prevention and control of this chronic infectious disease, leading to severe hepatopathies (cirrhosis and hepatocellular carcinoma).&#x0D; Furthermore, prolonged HBV viremia leads to depletion of the immune system, reducing resistance against pathogens of other infections, especially those with a chronic course and socially determined spread.&#x0D; The aim of this research is to evaluate existing animal models of HBV infection in the context of pathogenesis, immunologic and pathomorphological features. For the first time, the hypothesis of the possible use of certain models for the research of HBV-associated socially significant infections is considered from the point of view of the development of pathomorphological features.&#x0D; To complete this review, we analyzed the information about the features of HBV infection models in vivo, published over the last 25 years in open sources (Web of Science, PubMed, Scopus, ScienceDirect, Springer). The main criteria for literature selection were the type of infecting agent, the observed immunologic features of the course of the infectious process and the availability of a description of the pathomorphological features in model organisms.

CRISPR/Cas9 System with Dual gRNAs Synergically Inhibit Hepatitis B Virus Replication.

In recent years, a gene-editing technology known as clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 has been developed and is progressively advancing into clinical trials. While current antiviral therapies are unable to eliminate the Hepatitis B virus (HBV), it stands as a prime target for the CRISPR/Cas9 technology. The objective of this study was to enhance the efficacy of CRISPR/Cas9 in suppressing HBV replication, lowering HBsAg and HBeAg levels, and eliminating covalently closed circular DNA (cccDNA). To enhance the anti-HBV effectiveness of CRISPR/Cas9, our study delved into a dual-guide RNA (gRNA) strategy. After evaluating the antiviral activities of multiple gRNAs that effectively impeded HBV replication, we identified three specific gRNAs-namely 10, 4, and 21. These gRNAs were selected for their targeting of distinct yet conserved regions within the HBV genome. In HBV-stable cell lines, namely HepAD38, and HBV infection models of HepG2-NTCP cells, our investigation revealed that the co-application of gRNA-10 with either gRNA-4 or gRNA-21 within the CRISPR/Cas9 system demonstrated heightened efficacy in impeding HBV replication, reducing the levels of HBsAg, HBeAg, and cccDNA levels, along with a more pronounced promotion of HBsAg clearance when compared to the use of a single gRNA. The CRISPR/Cas9 system employing dual gRNAs has proven highly effective in both suppressing HBV replication and facilitating HBsAg clearance. This promising outcome suggests that it holds potential to emerge as a novel approach for achieving the functional cure of patients with HBV infection.

Optimized pretreatment increases the susceptibility of hepatitis B virus infection by enhancing actomyosin-driven cell spreading

Long-lasting infections by pathogens such as the hepatitis B virus (HBV) present growing threat to human health. The lack of an ideal infection cell model has been a major obstacle in HBV research before identification of NTCP as a receptor. However, the HepG2-NTCP cell model still exhibits notable inefficient HBV invasion competence. In this study, we successfully optimized the previous infection protocol by seeding cells in Opti-MEM in advance, which results in a substantial increase in HBV invasion rate. This optimization thus enabled higher viral levels with lower viral input. Mechanistically, we observed that Opti-MEM treatment remodeled the actomyosin cytoskeletal network and heightened myosin activity, leading to cell spreading for more chance of viral entry. Moreover, disruption of actomyosin architecture by pharmacological drugs prevents HBV entry without interfering the following viral replication. Together, our findings shed light on the supportive role of the actomyosin cytoskeleton network in HBV invasion, and offered a novel perspective for optimizing the HBV infection model.

Analysis of a delayed spatiotemporal model of HBV infection with logistic growth

In this paper, following previous works of ours, we deal with a mathematical model of hepatitis B virus (HBV) infection. We assume spatial diffusion of free HBV particles, logistic growth for both healthy and infected hepatocytes, and use the standard incidence function for viral infection. Moreover, one time delay is introduced to account for actual virus production. Another time delay is used to account for virus maturation. The existence, uniqueness, positivity and boundedness of solutions are established. Analyzing the model qualitatively and using a Lyapunov functional, we establish the existence of a threshold T 0 such that, if the basic reproduction number R 0 verifies R 0 ≤ T 0 < 1 , the infection-free equilibrium is globally asymptotically stable. When R 0 is greater than one, we discuss the local asymptotic stability of the unique endemic equilibrium and the occurrence of a Hopf bifurcation. Also, when R 0 is greater than one, the system is uniformly persistent, which means that the HBV infection is endemic. Finally, we carry out some relevant numerical simulations to clarify and interpret the theoretical results.

Interferon stimulated immune profile changes in a humanized mouse model of HBV infection

The underlying mechanism of chronic hepatitis B virus (HBV) functional cure by interferon (IFN), especially in patients with low HBsAg and/or young ages, is still unresolved due to the lack of surrogate models. Here, we generate a type I interferon receptor humanized mouse (huIFNAR mouse) through a CRISPR/Cas9-based knock-in strategy. Then, we demonstrate that human IFN stimulates gene expression profiles in huIFNAR peripheral blood mononuclear cells (PBMCs) are similar to those in human PBMCs, supporting the representativeness of this mouse model for functionally analyzing human IFN in vivo. Next, we reveal the tissue-specific gene expression atlas across multiple organs in response to human IFN treatment; this pattern has not been reported in healthy humans in vivo. Finally, by using the AAV-HBV model, we test the antiviral effects of human interferon. Fifteen weeks of human PEG-IFNα2 treatment significantly reduces HBsAg and HBeAg and even achieves HBsAg seroconversion. We observe that activation of intrahepatic monocytes and effector memory CD8 T cells by human interferon may be critical for HBsAg suppression. Our huIFNAR mouse can authentically respond to human interferon stimulation, providing a platform to study interferon function in vivo. PEG-IFNα2 treatment successfully suppresses intrahepatic HBV replication and achieves HBsAg seroconversion.

A novel investigation of the hepatitis B virus using a fractional operator with a non-local kernel

In order to understand and manage infectious illnesses, mathematical models are extremely important. They support decision making by researchers and public health workers in predicting the spread of diseases, evaluate the results of interventions, and gathering data. This study considers a fractionalized hepatitis B virus (HBV) infection model with cell cure. The Atangana Baleanu fractional model was initially established for the epidemic issue. This paper analyses the fractional form that makes up the HBV infection model utilizing the numerical methodology, homotopy analysis transform method (HATM). The suggested technique is created with the use of the homotopy analysis method (HAM), the homotopy polynomial, and the Laplace transformation. Additionally, the existence and uniqueness of the solution are considered, and stability analysis is given by the fixed-point theory (FPT) of the HBV model. Through MATLAB21, the obtained solutions are graphically simulated. The graphical solutions demonstrated that the peak of viral propagation is reduced when a fractional-order derivative is included to the model, and cell damage is minimized by starting treatment early on; however, the disease takes longer to be completely eradicated. The outcomes will be beneficial in the medical field. The fractional model lets us draw significant information essential for predicting disease outcomes and planning appropriate clinical management for patients.

Therapeutic vaccination with lentiviral vector in HBV-persistent mice and two inactive HBsAg carriers

Immunotherapy for chronic hepatitis B virus (HBV) infection has not yet demonstrated sufficient efficacy. We developed a non-integrative lentiviral-vectored therapeutic vaccine for chronic hepatitis B and tested its antiviral effects in HBV-persistent mice and two inactive HBsAg carriers. Lentiviral vectors (LVs) encoding the core, preS1, or large HBsAg (LHBs) proteins of HBV were evaluated for immunogenicity in HBV-naïve mice and therapeutic efficacy in a murine model of chronic HBV infection. In addition, two inactive HBsAg carriers each received two doses of 5×107 transduction units (TU) or 1×108 TU of lentiviral-vectored LHBs (LV-LHBs), respectively. The endpoints were safety, LHBs-specific T-cell responses, and serum HBsAg levels during a 24-week follow-up. In the mouse models, LV-LHBs was the most promising in eliciting robust antigen-specific T cells and in reducing the levels of serum HBsAg and viral load. By the end of the 34-week observation period, six out of ten (60%) HBV-persistent mice vaccinated with LV-LHBs achieved serum HBsAg loss and significant depletion of HBV-positive hepatocytes in the liver. In the two inactive HBsAg carriers, vaccination with LV-LHBs induced a considerable increase in the number of peripheral LHBs-specific T cells in one patient, and a weak but detectable response in the other, accompanied by a sustained reduction of HBsAg (-0.31 log10 IU/ml and -0.46 log10 IU/ml, respectively) from baseline to nadir. A lentiviral-vectored therapeutic vaccine for chronic HBV infection demonstrated the potential to improve HBV-specific T-cell responses and deplete HBV-positive hepatocytes, leading to a sustained loss or reduction of serum HBsAg. Chronic HBV infection is characterized by an extremely low number and profound hypo-responsiveness of HBV-specific T cells. Therapeutic vaccines are designed to improve HBV-specific T-cell responses. We show that immunization with a lentiviral-vectored therapeutic HBV vaccine was able to expand HBV-specific T cells invivo, leading to reductions of HBV-positive hepatocytes and serum HBsAg.

Aborted infection of human sodium taurocholate cotransporting polypeptide (hNTCP) expressing woodchuck hepatocytes with hepatitis B virus (HBV).

Due to the limited host range of HBV, research progress has been hindered by the absence of a suitable animal model. The natural history of woodchuck hepatitis virus (WHV) infection in woodchuck closely mirrors that of HBV infection in human, making this species a promising candidate for establishing both in vivo and in vitro HBV infection models. Therefore, this animal may be a valuable species to evaluate HBV vaccines and anti-HBV drugs. A significant milestone in HBV and hepatitis D virus (HDV) infection is the discovery of sodium taurocholate cotransporting polypeptide (NTCP) as the functional receptor. In an effort to enhance susceptibility to HBV infection, we introduced hNTCP into the woodchuck hepatocytes by multiple approaches including transduction of vLentivirus-hNTCP in woodchuck hepatocytes, transfection of p-lentivirus-hNTCP-eGFP plasmids into these cells, as well as transduction of vAdenovirus-hNTCP-eGFP. Encouragingly, our findings demonstrated the successful introduction of hNTCP into woodchuck hepatocytes. However, it was observed that these hNTCP-expressing hepatocytes were only susceptible to HDV infection but not HBV. This suggests the presence of additional crucial factors mediating early-stage HBV infection that are subject to stringent species-specific restrictions.

Hepatitis B Virus Envelope Antigen and Hepatitis B Virus Surface Antigen Both Contribute to the Innate Immune Response During Persistent Hepatitis B Virus Infection.

This study aimed to investigate the changes of toll-like receptor 4 (TLR4), proinflammatory cytokine expression, hepatitis B virus surface antigen (HBsAg), and hepatitis B virus envelope antigen (HBeAg) expression as well as innate immune cell percentages in a mouse model of persistent hepatitis B virus (HBV) infection to better understand the innate immune response. Mouse models of persistent HBV infection, HBsAg expression, and HBeAg expression were developed using high-pressure tail-vein injection of recombinant adeno-associated viruses. Enzyme-linked immunosorbent assays (ELISAs) were used to determine the serum proinflammatory cytokine levels. Immunohistochemistry and western blot assays were used to detect TLR4 expression. Flow cytometric analysis was used to assess the percentage of innate immune cells in the whole blood. Persistent HBV infection, HBsAg expression, and HBeAg expression each significantly decreased the expression of TLR4. Persistent HBV infection significantly increased the percentages of T cells and monocytes, whereas it decreased the percentage of natural killer (NK) cells. Persistent HBeAg expression also decreased the percentage of NK cells, whereas persistent HBsAg expression increased the percentage of NK cells. Both persistent HBsAg and HBeAg expression increased the percentage of monocytes. However, both persistent HBsAg and HBeAg expression decreased the percentage of T cells. HBV as well as HBsAg and HBeAg showed similar effects on the expression of TLR4 and proinflammatory cytokines as well as the percentage of monocytes. Persistent HBV infection increased the percentage of T cells and decreased the percentage of NK cells, whereas only persistent HBeAg expression contributed to a decreased percentage of NK cells.

Fractional‐order models of hepatitis B virus infection with recycling effects of capsids

Hepatitis B virus (HBV) infection is a major public health concern throughout the world. It can be treated effectively through proper medication and vaccination, although it is very difficult to cure, especially in people who have had the chronic infection. So, it is necessary to pay proper attention for its eradication. In this study, two nonlinear fractional‐order HBV infection models with recycling effects of capsids are presented via the Caputo derivative. Each model contains four compartments, namely, susceptible hepatocytes, infected hepatocytes, HBV capsids, and viruses. In the first model, the order of fractional derivatives is equal for each compartment, whereas, in the second model, the order is incommensurate. The existence and uniqueness of solutions for both models are discussed separately. The parameters are estimated in order to validate the proposed model with experimental data obtained from a chimpanzee. Stability analyses are carried out for both models theoretically. The models are solved numerically using the predictor–corrector Adams–Bashforthm–Moulton method (for commensurate order) and implicit product integration of trapezoidal type method (for incommensurate order) with various choices of fractional orders and initial conditions. All the results are presented graphically. Interestingly, the results reveal the importance of fractional‐order derivatives in capturing the dynamics of HBV transmission in the host. It is also noticed that with the decrease in the order of fractional derivative, the peak level of infection decreases, but the disease takes a long time to be cured.

Qualitative and Quantitative Analysis of Fractional Dynamics of Infectious Diseases with Control Measures

Infectious diseases can have a significant economic impact, both in terms of healthcare costs and lost productivity. This can be particularly significant in developing countries, where infectious diseases are more prevalent, and healthcare systems may be less equipped to handle them. It is recognized that the hepatitis B virus (HBV) infection remains a critical global public health issue. In this study, we develop a comprehensive model for HBV infection that includes vaccination and hospitalization through a fractional framework. It has been shown that the solutions of the recommended system of HBV infection are positive and bounded. We examine the steady states of the model and determine the basic reproduction number; denoted by R0. The qualitative and quantitative behavior of the model is demonstrated using mathematical skills and numerical techniques. It has been proved that the infection-free steady state of the system is locally asymptotically stable if R0&lt;1 and unstable otherwise. Furthermore, the Ulam–Hyers stability (UHS) of the recommended fractional models is investigated and the significant conditions are provided. We present an iterative technique to visualize the dynamical behavior of the system. We perform different simulations to illustrate the effect of different input factors on the solution pathways of the system of HBV infection to conceptualize the role of parameters in the control and prevention of the infection.

Dynamics of a Diffusive HBV Infection Model with Capsids, Two Delays, and Cell-to-Cell Transmissions

This article aims to study a hepatitis B virus (HBV) infection model incorporating two nonlinear incidences and spatial diffusion in capsids, virus, and cytotoxic T lymphocyte (CTL) immune response. Three equilibria which are infection-free, immune-free, and infection with CTL immunity are calculated under rational assumptions. Furthermore, two reproduction numbers are verified to assert the global stability of the HBV model. In the end, the theoretical results on HBV dynamics are further illustrated by performing numerical simulations.