CD40 stimulation activates CD8+ T cells and controls HBV in CD4-depleted mice.

Background & Aims: HBV treatment is challenging due to the persistence of the covalently closed circular DNA replication pool, which remains unaffected by antiviral intervention. In this study, we determined whether targeting antigen-presenting cells via CD40 stimulation represents an appropriate therapeutic approach for achieving sustained HBV control in a mouse model of HBV replication.

Methods: Mice were transduced with an adeno-associated virus encoding the HBV genome (AAV-HBV) to initiate HBV replication and were administered agonistic CD40 antibody.

CD4 T cells reverse surface antigen persistence in a mouse model of HBV replication.

Hepatitis B virus (HBV) is a leading causative agent of viral hepatitis. A preventative vaccine has existed for decades, but only limited treatment options are available for people living with chronic HBV. Animal models for studying HBV are constrained due to narrow viral tropism, impeding understanding of the natural immune response to the virus.

Alternating Arenavirus Vector Immunization Generates Robust Polyfunctional Genotype Cross-Reactive Hepatitis B Virus-Specific CD8 T-Cell Responses and High Anti-Hepatitis B Surface Antigen Titers.

Hepatitis B Virus (HBV) is a major driver of infectious disease mortality. Curative therapies are needed and ideally should induce CD8 T cell-mediated clearance of infected hepatocytes plus anti-hepatitis B surface antigen (HBsAg) antibodies (anti-HBs) to neutralize residual virus. We developed a novel therapeutic vaccine using non-replicating arenavirus vectors.

Virus-based vaccine vectors with distinct replication mechanisms differentially infect and activate dendritic cells.

The precise mechanism by which many virus-based vectors activate immune responses remains unknown. Dendritic cells (DCs) play key roles in priming T cell responses and controlling virus replication, but their functions in generating protective immunity following vaccination with viral vectors are not always well understood. We hypothesized that highly immunogenic viral vectors with identical cell entry pathways but unique replication mechanisms differentially infect and activate DCs to promote antigen presentation and activation of distinctive antigen-specific T cell responses.

Lack of active SARS-CoV-2 virus in a subset of PCR-positive COVID-19 congregate care patients.

Highly sensitive nucleic acid amplification tests (NAATs) designed to detect SARS-CoV-2 RNA are the standard of care for the diagnosis of COVID-19. However, the accuracy of these methods for the quantitation of active virus rather than non-infectious RNA fragments that can persist for extended periods of time has been unclear. This issue is particularly relevant for congregate care patients who are unable to return to their home residence until fully negative by NAATs.

Blood DNA methylation and COVID-19 outcomes.

Background: There are no prior reports that compare differentially methylated regions of DNA in blood samples from COVID-19 patients to samples collected before the SARS-CoV-2 pandemic using a shared epigenotyping platform. We performed a genome-wide analysis of circulating blood DNA CpG methylation using the Infinium Human MethylationEPIC BeadChip on 124 blood samples from hospitalized COVID-19-positive and COVID-19-negative patients and compared these data with previously reported data from 39 healthy individuals collected before the pandemic. Prospective outcome measures such as COVID-19-GRAM risk-score and mortality were combined with methylation data.

Innate immunity and HBV persistence.

Hepatitis B virus (HBV) causes chronic infections that are associated with immune dysfunction. Though T cell impairment is perhaps the most prominent immune change contributing to viral persistence, HBV interaction with the innate immune system is also likely key, as the lack of effective innate immunity has functional consequences that promote chronic infection. In addition to an intrinsic ability to fight viral infections, the innate immune system also impacts T cell responses and other adaptive immune mechanisms critical for HBV control.

xCT/SLC7A11 antiporter function inhibits HIV-1 infection.

Human macrophages are protected by intrinsic antiviral defenses that provide moderate protection against HIV-1 infection. Macrophages that do become infected can serve as long-lived reservoirs, to disseminate HIV-1 to CD4 T cells. Infection of macrophages with HIV-1 and HIV-2 is inhibited by constitutive mobilization of antioxidant response master transcription regulator Nrf2.

Modified Alphavirus-Vesiculovirus Hybrid Vaccine Vectors for Homologous Prime-Boost Immunotherapy of Chronic Hepatitis B.

Virus-like vesicles (VLV) are hybrid vectors based on an evolved Semliki Forest virus (SFV) RNA replicon and the envelope glycoprotein (G) from vesicular stomatitis virus (VSV) [...

Mucin-Like Domain of Ebola Virus Glycoprotein Enhances Selective Oncolytic Actions against Brain Tumors.

Given that the Ebola virus (EBOV) infects a wide array of organs and cells yet displays a relative lack of neurotropism, we asked whether a chimeric vesicular stomatitis virus (VSV) expressing the EBOV glycoprotein (GP) might selectively target brain tumors. The mucin-like domain (MLD) of the EBOV GP may enhance virus immune system evasion. Here, we compared chimeric VSVs in which EBOV GP replaces the VSV glycoprotein, thereby reducing the neurotoxicity associated with wild-type VSV.

Virus-like Vesicles Expressing Multiple Antigens for Immunotherapy of Chronic Hepatitis B.

Infections with hepatitis B virus (HBV) can initiate chronic hepatitis and liver injury, causing more than 600,000 deaths each year worldwide. Current treatments for chronic hepatitis B are inadequate and leave an unmet need for immunotherapeutic approaches. We designed virus-like vesicles (VLV) as self-amplifying RNA replicons expressing three HBV antigens (polymerase, core, and middle surface) from a single vector (HBV-VLV) to break immune exhaustion despite persistent HBV replication.

Mechanisms of Innate Immune Activation by a Hybrid Alphavirus-Rhabdovirus Vaccine Platform.

Virus-like vesicles (VLV) are infectious, self-propagating alphavirus-vesiculovirus hybrid vaccine vectors that can be engineered to express foreign antigens to elicit a protective immune response. VLV are highly immunogenic and nonpathogenic , and we hypothesize that the unique replication and structural characteristics of VLV efficiently induce an innate antiviral response that enhances immunogenicity and limits replication and spread of the vector. We found that VLV replication is inhibited by interferon (IFN)-α, IFN-γ, and IFN-λ, but not by tumor necrosis factor-α.

Heterologous prime-boost immunization with vesiculovirus-based vectors expressing HBV Core antigen induces CD8 T cell responses in naïve and persistently infected mice and protects from challenge.

Chronic hepatitis B virus (HBV) infections cause more than 800,000 deaths per year and currently approved treatments do not cure the disease. Because a hallmark of acute infection resolution is the presence of functional CD8 T cells to the virus, activation of the immune system with therapeutic vaccines represents a potential approach for treating chronic hepatitis B. In this study, we evaluated the immunogenicity and efficacy of two attenuated vesiculovirus-based platforms expressing HBV Core antigen, the highly attenuated vesicular stomatitis virus (VSV) N4CT1 and a unique vaccine platform [virus-like vesicles (VLV)] that is based on a Semliki Forest virus replicon expressing the VSV glycoprotein.

A Highly Attenuated Vesicular Stomatitis Virus-Based Vaccine Platform Controls Hepatitis B Virus Replication in Mouse Models of Hepatitis B.

Therapeutic vaccines may be an important component of a treatment regimen for curing chronic hepatitis B virus (HBV) infection. We previously demonstrated that recombinant wild-type vesicular stomatitis virus (VSV) expressing the HBV middle surface glycoprotein (MHBs) elicits functional immune responses in mouse models of HBV replication. However, VSV has some undesirable pathogenic properties, and the use of this platform in humans requires further viral attenuation.

An ELISPOT-Based Assay to Measure HBV-Specific CD8 T Cell Responses in Immunocompetent Mice.

Despite some important limitations, immunocompetent mouse models of HBV replication remain an essential tool for studying cellular and humoral immunity to the virus. CD8 T cells are a critical component of the immune response to HBV due to their ability to both kill virus-infected hepatocytes and produce cytokines such as IFN-γ that non-cytopathically inhibit virus replication. A number of techniques can be used to measure the magnitude, specificity, and functionality of HBV-specific CD8 T cells, each having its own unique advantages.

Virus-Like Vesicle-Based Therapeutic Vaccine Vectors for Chronic Hepatitis B Virus Infection.

Unlabelled: More than 500,000 people die each year from the liver diseases that result from chronic hepatitis B virus (HBV) infection. Therapeutic vaccines, which aim to elicit an immune response capable of controlling the virus, offer a potential new treatment strategy for chronic hepatitis B. Recently, an evolved, high-titer vaccine platform consisting of Semliki Forest virus RNA replicons that express the vesicular stomatitis virus glycoprotein (VSV G) has been described.

Type III interferon attenuates a vesicular stomatitis virus-based vaccine vector.

Unlabelled: Vesicular stomatitis virus (VSV) has been extensively studied as a vaccine vector and oncolytic agent. Nevertheless, safety concerns have limited its widespread use in humans. The type III lambda interferon (IFN-λ) family of cytokines shares common signaling pathways with the IFN-α/β family and thus evokes similar antiviral activities.

Long-distance interferon signaling within the brain blocks virus spread.

Unlabelled: Serious permanent neurological or psychiatric dysfunction may result from virus infections in the central nervous system (CNS). Olfactory sensory neurons are in direct contact with the external environment, making them susceptible to infection by viruses that can enter the brain via the olfactory nerve. The rarity of full brain viral infections raises the important question of whether unique immune defense mechanisms protect the brain.

Epigenetic reprogramming of the type III interferon response potentiates antiviral activity and suppresses tumor growth.

Type III interferon (IFN-λ) exhibits potent antiviral activity similar to IFN-α/β, but in contrast to the ubiquitous expression of the IFN-α/β receptor, the IFN-λ receptor is restricted to cells of epithelial origin. Despite the importance of IFN-λ in tissue-specific antiviral immunity, the molecular mechanisms responsible for this confined receptor expression remain elusive. Here, we demonstrate that the histone deacetylase (HDAC) repression machinery mediates transcriptional silencing of the unique IFN-λ receptor subunit (IFNLR1) in a cell-type-specific manner.

Functional characterization of the putative hepatitis B virus core protein late domain using retrovirus chimeras.

The hepatitis B virus (HBV) Core protein encodes a late (L)-domain like motif (129PPAYRPPNAP(138)) that has been purported to serve as a docking site for recruitment of host factors such as Nedd4 that can mediate viral particle release from infected cells. However, mutation of this region of Core typically disrupts nucleocapsid formation in the cytoplasm, making it difficult to ascertain if the Core PPAY motif constitutes a functional L-domain that mediates HBV release in the context of replicating virus. Since many viral L-domains are functionally interchangeable between different virus families, and such swapping experiments have been used as a tool to identify other viral sequences with L-domain activity, we generated chimeric constructs between murine leukemia virus (MLV) Gag and HBV Core to determine if the potential HBV L-domain motif is sufficient to stimulate virus release.

Dynamic expression profiling of type I and type III interferon-stimulated hepatocytes reveals a stable hierarchy of gene expression.

Despite activating similar signaling cascades, the type I and type III interferons (IFNs) differ in their ability to antagonize virus replication. However, it is not clear whether these cytokines induce unique antiviral states, particularly in the liver, where the clinically important hepatitis B and C viruses cause persistent infection. Here, clustering and promoter analyses of microarray-based gene expression profiling were combined with mechanistic studies of signaling pathways to dynamically characterize the transcriptional responses induced by these cytokines in Huh7 hepatoma cells and primary human hepatocytes.

A vesicular stomatitis virus-based therapeutic vaccine generates a functional CD8 T cell response to hepatitis B virus in transgenic mice.

Recombinant vesicular stomatitis virus (VSV) is a promising therapeutic vaccine platform. Using a transgenic mouse model of chronic hepatitis B virus (HBV) infection, we evaluated the therapeutic potential of a VSV vector expressing the HBV middle surface envelope glycoprotein (MS). VSV-MS immunization generated HBV-specific CD8 T cell and antibody responses in transgenic mice that express low HBV antigen levels.

Protective and pathological properties of IL-22 in liver disease: implications for viral hepatitis.

Chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infection affect >500 million people worldwide and are significant causes of liver cirrhosis and hepatocellular carcinoma. The pathogenesis of HBV and HCV infection can vary widely with respect to the outcome of initial infection to self-resolving acute or chronic disease, the extent of viremia and liver inflammation during chronic infection, and the eventual development of liver cirrhosis and hepatocellular carcinoma. The host immune response is an important factor in the variable consequences of these infections, because the innate and adaptive intrahepatic antiviral responses are an intricate balance of immune effector cells and cytokines that control virus replication but can also cause liver damage.