Viral proteins recognized by different TLRs.

Virus invasion activates the host's innate immune response, inducing the production of numerous cytokines and interferons to eliminate pathogens. Except for viral DNA/RNA, viral proteins are also targets of pattern recognition receptors. Membrane-bound receptors such as Toll-like receptor (TLR)1, TLR2, TLR4, TLR6, and TLR10 relate to the recognition of viral proteins. Distinct TLRs perform both protective and detrimental roles for a specific virus. Here, we review viral proteins serving as pathogen-associated molecular patterns and their corresponding TLRs. These viruses are all enveloped, including respiratory syncytial virus, hepatitis C virus, measles virus, herpesvirus human immunodeficiency virus, and coronavirus, and can encode proteins to activate innate immunity in a TLR-dependent way. The TLR-viral protein relationship plays an important role in innate immunity activation. A detailed understanding of their pathways contributes to a novel direction for vaccine development.

Hepatitis C Screening and Treatment Program in Hungarian Prisons in the Era of Direct Acting Antiviral Agents.

A hepatitis C virus (HCV) screening and treatment program was conducted in Hungarian prisons on a voluntary basis. After HCV-RNA testing and genotyping for anti-HCV positives, treatments with direct-acting antiviral agents were commenced by hepatologists who visited the institutions monthly. Patients were supervised by the prisons' medical staff. Data were retrospectively collected from the Hungarian Hepatitis Treatment Registry, from the Health Registry of Prisons, and from participating hepatologists. Eighty-four percent of Hungarian prisons participated, meaning a total of 5779 individuals (28% of the inmate population) underwent screening. HCV-RNA positivity was confirmed in 317/5779 cases (5.49%); 261/317 (82.3%) started treatment. Ninety-nine percent of them admitted previous intravenous drug use. So far, 220 patients received full treatment and 41 patients are still on treatment. Based on the available end of treatment (EOT) + 24 weeks timepoint data, per protocol sustained virologic response rate was 96.8%. In conclusion, the Hungarian prison screening and treatment program, with the active participation of hepatologists and the prisons' medical staff, is a well-functioning model. Through the Hungarian experience, we emphasize that the "test-and-treat" principle is feasible and effective at micro-eliminating HCV in prisons, where infection rate, as well as history of intravenous drug usage, are high.

Viral Glycoproteins Induce NLRP3 Inflammasome Activation and Pyroptosis in Macrophages.

Infections with viral pathogens are widespread and can cause a variety of different diseases. In-depth knowledge about viral triggers initiating an immune response is necessary to decipher viral pathogenesis. Inflammasomes, as part of the innate immune system, can be activated by viral pathogens. However, viral structural components responsible for inflammasome activation remain largely unknown. Here we analyzed glycoproteins derived from SARS-CoV-1/2, HCMV and HCV, required for viral entry and fusion, as potential triggers of NLRP3 inflammasome activation and pyroptosis in THP-1 macrophages. All tested glycoproteins were able to potently induce NLRP3 inflammasome activation, indicated by ASC-SPECK formation and secretion of cleaved IL-1ß. Lytic cell death via gasdermin D (GSDMD), pore formation, and pyroptosis are required for IL-1ß release. As a hallmark of pyroptosis, we were able to detect cleavage of GSDMD and, correspondingly, cell death in THP-1 macrophages. CRISPR-Cas9 knockout of NLRP3 and GSDMD in THP-1 macrophages confirmed and strongly support the evidence that viral glycoproteins can act as innate immunity triggers. With our study, we decipher key mechanisms of viral pathogenesis by showing that viral glycoproteins potently induce innate immune responses. These insights could be beneficial in vaccine development and provide new impulses for the investigation of vaccine-induced innate immunity.

Structural and Biophysical Characterization of the HCV E1E2 Heterodimer for Vaccine Development.

An effective vaccine for the hepatitis C virus (HCV) is a major unmet medical and public health need, and it requires an antigen that elicits immune responses to multiple key conserved epitopes. Decades of research have generated a number of vaccine candidates; based on these data and research through clinical development, a vaccine antigen based on the E1E2 glycoprotein complex appears to be the best choice. One bottleneck in the development of an E1E2-based vaccine is that the antigen is challenging to produce in large quantities and at high levels of purity and antigenic/functional integrity. This review describes the production and characterization of E1E2-based vaccine antigens, both membrane-associated and a novel secreted form of E1E2, with a particular emphasis on the major challenges facing the field and how those challenges can be addressed.

Effects of chloroquine or hydroxychloroquine treatment on non-SARS-CoV2 viral infections: A systematic review of clinical studies.

Chloroquine (CQ) and hydroxychloroquine (HCQ) have been used as antiviral agents for the treatment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection. We performed a systematic review to examine whether prior clinical studies that compared the effects of CQ and HCQ to a control for the treatment of non-SARS-CoV2 infection supported the use of these agents in the present SARS-CoV2 outbreak. PubMed, EMBASE, Scopus and Web of Science (PROSPERO CRD42020183429) were searched from inception through 2 April 2020 without language restrictions. Of 1766 retrieved reports, 18 studies met our inclusion criteria, including 17 prospective controlled studies and one retrospective study. CQ or HCQ were compared to control for the treatment of infectious mononucleosis (EBV, n = 4), warts (human papillomavirus, n = 2), chronic HIV infection (n = 6), acute chikungunya infection (n = 1), acute dengue virus infection (n = 2), chronic HCV (n = 2), and as preventive measures for influenza infection (n = 1). Survival was not evaluated in any study. For HIV, the virus that was most investigated, while two early studies suggested HCQ reduced viral levels, four subsequent ones did not, and in two of these CQ or HCQ increased viral levels and reduced CD4 counts. Overall, three studies concluded CQ or HCQ were effective; four concluded further research was needed to assess the treatments' effectiveness; and 11 concluded that treatment was ineffective or potentially harmful. Prior controlled clinical trials with CQ and HCQ for non-SARS-CoV2 viral infections do not support these agents' use for the SARS-CoV2 outbreak.

A modular framework for multiscale, multicellular, spatiotemporal modeling of acute primary viral infection and immune response in epithelial tissues and its application to drug therapy timing and effectiveness.

Simulations of tissue-specific effects of primary acute viral infections like COVID-19 are essential for understanding disease outcomes and optimizing therapies. Such simulations need to support continuous updating in response to rapid advances in understanding of infection mechanisms, and parallel development of components by multiple groups. We present an open-source platform for multiscale spatiotemporal simulation of an epithelial tissue, viral infection, cellular immune response and tissue damage, specifically designed to be modular and extensible to support continuous updating and parallel development. The base simulation of a simplified patch of epithelial tissue and immune response exhibits distinct patterns of infection dynamics from widespread infection, to recurrence, to clearance. Slower viral internalization and faster immune-cell recruitment slow infection and promote containment. Because antiviral drugs can have side effects and show reduced clinical effectiveness when given later during infection, we studied the effects on progression of treatment potency and time-of-first treatment after infection. In simulations, even a low potency therapy with a drug which reduces the replication rate of viral RNA greatly decreases the total tissue damage and virus burden when given near the beginning of infection. Many combinations of dosage and treatment time lead to stochastic outcomes, with some simulation replicas showing clearance or control (treatment success), while others show rapid infection of all epithelial cells (treatment failure). Thus, while a high potency therapy usually is less effective when given later, treatments at late times are occasionally effective. We illustrate how to extend the platform to model specific virus types (e.g., hepatitis C) and add additional cellular mechanisms (tissue recovery and variable cell susceptibility to infection), using our software modules and publicly-available software repository.

Impact of the 2020 COVID-19 Pandemic on Ambulatory Hepatitis C Testing.

INTRODUCTION: Coronavirus disease 2019 (COVID-19) has led to unprecedented modifications to healthcare delivery in the U.S. To preserve resources in preparation for a COVID-19 surge, Boston Medical Center (BMC) implemented workflows to decrease ambulatory in-person visits effective March 16th, 2020. Telemedicine was incorporated into clinical workflows and much preventive care, including Hepatitis C (HCV) testing, was not routinely performed. OBJECTIVE: To explore the impact that the COVID-19 rapid restructuring response has had on HCV testing and identification hospital-wide and in ambulatory settings. METHODS: BMC utilizes reflex confirmatory testing for HCV. When a sample is HCV Ab positive, it is automatically reflexed for confirmatory RNA and genotype testing. HCV test results for patients were collected daily. We compared unique patient tests for 3.5 month periods before and after March 16th, 2020. Descriptive statistics showed total tests and total new HCV RNA+ before versus after, both hospital-wide and in ambulatory clinics alone. Mean daily tests completed were compared. RESULTS: Hospital-wide, total HCV testing decreased by 49.6%, and new HCV+ patient identification decreased by 42.1%. In ambulatory clinics, testing decreased by 71.9%, and new HCV+ identification decreased by 63.3%. Hospital-wide, mean daily tests decreased by 22.9 tests per day (95% CI: 17.9-28.0, P < .001), and mean daily new HCV+ identification decreased by 0.36 (95% CI: 0.20-0.53, P < .001). In ambulatory clinics, mean daily tests decreased by 22.1 tests per day (95% CI: 17.5-26.7, P < .001) and mean daily HCV+ decreased by 1.40 (95% CI: 1.03-1.76, P < .001). CONCLUSION: The COVID-19 systematic emergency response led to decreased HCV testing and identification, and in this regard telemedicine acts as a barrier to HCV care. Other public health initiatives must be monitored in the context of telemedicine workflows. Continued monitoring of HCV screening trends is vital, and adaptive approaches to work toward the goal of HCV elimination are needed.

Optimized cell systems for the investigation of hepatitis C virus E1E2 glycoproteins.

Great strides have been made in understanding and treating hepatitis C virus (HCV) thanks to the development of various experimental systems including cell-culture-proficient HCV, the HCV pseudoparticle system and soluble envelope glycoproteins. The HCV pseudoparticle (HCVpp) system is a platform used extensively in studies of cell entry, screening of novel entry inhibitors, assessing the phenotypes of clinically observed E1 and E2 glycoproteins and, most pertinently, in characterizing neutralizing antibody breadth induced upon vaccination and natural infection in patients. Nonetheless, some patient-derived clones produce pseudoparticles that are either non-infectious or exhibit infectivity too low for meaningful phenotyping. The mechanisms governing whether any particular clone produces infectious pseudoparticles are poorly understood. Here we show that endogenous expression of CD81, an HCV receptor and a cognate-binding partner of E2, in producer HEK 293T cells is detrimental to the infectivity of recovered HCVpp for most strains. Many HCVpp clones exhibited increased infectivity or had their infectivity rescued when they were produced in 293T cells CRISPR/Cas9 engineered to ablate CD81 expression (293TCD81KO). Clones made in 293TCD81KO cells were antigenically very similar to their matched counterparts made parental cells and appear to honour the accepted HCV entry pathway. Deletion of CD81 did not appreciably increase the recovered titres of soluble E2 (sE2). However, we did, unexpectedly, find that monomeric sE2 made in 293T cells and Freestyle 293-F (293-F) cells exhibit important differences. We found that 293-F-produced sE2 harbours mostly complex-type glycans whilst 293T-produced sE2 displays a heterogeneous mixture of both complex-type glycans and high-mannose or hybrid-type glycans. Moreover, sE2 produced in 293T cells is antigenically superior; exhibiting increased binding to conformational antibodies and the large extracellular loop of CD81. In summary, this work describes an optimal cell line for the production of HCVpp and reveals that sE2 made in 293T and 293-F cells are not antigenic equals. Our findings have implications for functional studies of E1E2 and the production of candidate immunogens.