Naturally acquired equine parvovirus-hepatitis is associated with a wide range of hepatic lesions in horses

Equine parvovirus-hepatitis (EqPV-H) is the causative agent of Theiler's disease, or severe acute hepatic necrosis, in horses. However, it is poorly understood whether EqPV-H is associated with other histologic findings in horses with clinical liver disease. The objective of this study was to examine the prevalence and severity of EqPV-H infections in diagnostic liver samples. Archived formalin-fixed, paraffin-embedded (FFPE) liver samples (n = 98) from Cornell University and University of California, Davis, collected between 2007 and 2022 were evaluated for 15 individual histologic features and by EqPV-H in situ hybridization. EqPV-H was detected in 48% (n = 47) of samples. The most common histologic features of EqPV-H-positive samples included individual hepatocyte death (n = 40, 85%), lobular infiltrates (n = 38, 80%), portal infiltrates (n = 35, 74%), and ductular reaction (n = 33, 70%). Centrilobular necrosis, portal infiltrate, and individual hepatocyte death were positively associated with high viral load. Neutrophil infiltrates, bridging fibrosis, and portal edema were negatively associated with a high viral load. Only 4 of 49 tested samples were positive for equine hepacivirus by polymerase chain reaction (PCR), but the PCR assay was unreliable for FFPE tissues. In summary, this study demonstrates that EqPV-H is common in a variety of liver pathologies and should be considered as a differential diagnosis in cases of hepatitis other than Theiler's disease.

Therapy as prevention toward HCV elimination in maintenance hemodialysis: a multi-center, prospective cohort study

Background

The World Health Organization has established interim guidance for hepatitis C virus (HCV) elimination. We aimed to prove the concept of "treatment as prevention" by conducting a prospective HCV elimination program for hemodialysis (HD) patients.

Methods

A universal HCV screen was launched in 22 HD centers in 2019. HCV-viremic patients were linked to care with direct-acting antivirals (DAAs). The second screen was performed in 2021 to evaluate the effect of link-to-care in lowering the prevalence of HCV viremia and the incidence of HCV new/re-infections.

Results

Of 2336 patients enrolled in the first screening in 2019, 320 (13.7%) were seropositive for anti-HCV and 181 (7.7%) were HCV-viremic. Of 152 patients successfully linked to treat with DAA, 140 (92.1%) patients achieved a sustained virological response. Of them, 1733 patients participated in the second surveillance. Five anti-HCV-negative patients experienced anti-HCV seroconversion. Of 119 DAA-cured patients and 102 spontaneous HCV clearance patients, none had HCV reinfection. The annual incidence of HCV new infection was 0.1%. Sixty-one of the 620 (9.8%) newly enrolled patients were anti-HCV-seropositive in the second survey. The overall HCV-viremic rate decreased from 7.7% in 2019 to 0.6% (15/2353) in 2021. At the institutional level, 45.5% (10/22) eradicated HCV and 82% (18/22) of HD units had no HCV new infections or reinfections.

Conclusions

The link-to-care project proved the concept of "treatment as prevention" by which HCV microelimination helps to prevent reinfection and new infections in the HD population.Trial registration: ClinicalTrials.gov identifier: NCT03803410 and NCT03891550.

The evolutionary history of hepaciviruses

In the search for natural reservoirs of hepatitis C virus (HCV), a broad diversity of non-human viruses within the Hepacivirus genus has been uncovered. However, the evolutionary dynamics that shaped the diversity and timescale of hepaciviruses evolution remain elusive. To gain further insights into the origins and evolution of this genus, we screened a large dataset of wild mammal samples (n = 1,672) from Africa and Asia, and generated 34 full-length hepacivirus genomes. Phylogenetic analysis of these data together with publicly available genomes emphasizes the importance of rodents as hepacivirus hosts and we identify 13 rodent species and 3 rodent genera (in Cricetidae and Muridae families) as novel hosts of hepaciviruses. Through co-phylogenetic analyses, we demonstrate that hepacivirus diversity has been affected by cross-species transmission events against the backdrop of detectable signal of virus-host co-divergence in the deep evolutionary history. Using a Bayesian phylogenetic multidimensional scaling approach, we explore the extent to which host relatedness and geographic distances have structured present-day hepacivirus diversity. Our results provide evidence for a substantial structuring of mammalian hepacivirus diversity by host as well as geography, with a somewhat more irregular diffusion process in geographic space. Finally, using a mechanistic model that accounts for substitution saturation, we provide the first formal estimates of the timescale of hepacivirus evolution and estimate the origin of the genus to be about 22 million years ago. Our results offer a comprehensive overview of the micro- and macroevolutionary processes that have shaped hepacivirus diversity and enhance our understanding of the long-term evolution of the Hepacivirus genus.

Molecular Determinants of Mouse Adaptation of Rat Hepacivirus

The lack of robust immunocompetent animal models for hepatitis C virus (HCV) impedes vaccine development and studies of immune responses. Norway rat hepacivirus (NrHV) infection in rats shares HCV-defining characteristics, including hepatotropism, chronicity, immune responses, and aspects of liver pathology. To exploit genetic variants and research tools, we previously adapted NrHV to prolonged infection in laboratory mice. Through intrahepatic RNA inoculation of molecular clones of the identified variants, we here characterized four mutations in the envelope proteins responsible for mouse adaptation, including one disrupting a glycosylation site. These mutations led to high-titer viremia, similar to that observed in rats. In 4-week-old mice, infection was cleared after around 5 weeks compared to 2 to 3 weeks for nonadapted virus. In contrast, the mutations led to persistent but attenuated infection in rats, and they partially reverted, accompanied by an increase in viremia. Attenuated infection in rat but not mouse hepatoma cells demonstrated that the characterized mutations were indeed mouse adaptive rather than generally adaptive across species and that species determinants and not immune interactions were responsible for attenuation in rats. Unlike persistent NrHV infection in rats, acute resolving infection in mice was not associated with the development of neutralizing antibodies. Finally, infection of scavenger receptor B-I (SR-BI) knockout mice suggested that adaptation to mouse SR-BI was not a primary function of the identified mutations. Rather, the virus may have adapted to lower dependency on SR-BI, thereby potentially surpassing species-specific differences. In conclusion, we identified specific determinants of NrHV mouse adaptation, suggesting species-specific interactions during entry. IMPORTANCE A prophylactic vaccine is required to achieve the World Health Organization's objective for hepatitis C virus elimination as a serious public health threat. However, the lack of robust immunocompetent animal models supporting hepatitis C virus infection impedes vaccine development as well as studies of immune responses and viral evasion. Hepatitis C virus-related hepaciviruses were discovered in a number of animal species and provide useful surrogate infection models. Norway rat hepacivirus is of particular interest, as it enables studies in rats, an immunocompetent and widely used small laboratory animal model. Its adaptation to robust infection also in laboratory mice provides access to a broader set of mouse genetic lines and comprehensive research tools. The presented mouse-adapted infectious clones will be of utility for reverse genetic studies, and the Norway rat hepacivirus mouse model will facilitate studies of hepacivirus infection for in-depth characterization of virus-host interactions, immune responses, and liver pathology.

Interventions for dialysis patients with hepatitis C virus (HCV) infection

BACKGROUND

Hepatitis C virus (HCV) infection is common in chronic kidney disease (CKD) patients on dialysis, causes chronic liver disease, may increase the risk of death, and impacts kidney transplant outcomes. Direct-acting antivirals have replaced interferons because of better efficacy and tolerability. This is an update of a review first published in 2015.

OBJECTIVES

We aimed to look at the benefits and harms of interventions for HCV in CKD patients on dialysis: death, disease relapse, treatment response/discontinuation, time to recovery, quality of life (QoL), cost-effectiveness, and adverse events. We aimed to study comparisons of available interventions, compared with placebo, control, with each other and with newer treatments.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant's Specialised Register to 23 February 2023 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE and EMBASE, handsearching conference proceedings, and searching the International Clinical Trials Register Portal (ICTRP) and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs), quasi-RCTs, first period of randomised cross-over studies on interventions for HCV in CKD on dialysis were considered.

DATA COLLECTION AND ANALYSIS

Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI). Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

Three studies were included in this update, therefore 13 studies (997 randomised participants) met our inclusion criteria. Overall, the risk of bias was judged low in seven studies, unclear in four, low to unclear in one, and high in one study. Interventions included standard interferon, pegylated (PEG) interferon, standard or PEG interferon plus ribavirin; direct-acting antivirals, and direct-acting antivirals plus PEG interferon plus ribavirin. Compared to placebo or control, standard interferon may make little or no difference to death (5 studies, 134 participants: RR 0.89, 95% CI 0.06 to 13.23) or relapse (low certainty evidence), probably improves end-of-treatment response (ETR) (5 studies, 132 participants: RR 8.62, 95% CI 3.03 to 24.55; I² = 0%) (moderate certainty evidence), and probably makes little or no difference to sustained virological response (SVR) (4 studies, 98 participants: RR 3.25, 95% CI 0.81 to 13.07; I² = 53%), treatment discontinuation (4 studies, 116 participants: RR 4.59, 95% CI 0.49 to 42.69; I² = 63%), and adverse events (5 studies, 143 participants: RR 3.56, 95% CI 0.98 to 13.01; I² = 25%) (moderate certainty evidence). In low certainty evidence, PEG interferon (1 study, 50 participants) may improve ETR (RR 1.53, 95% CI 1.09 to 2.15) but may make little or no difference to death (RR 0.33, 95% CI 0.01 to 7.81), SVR (RR 2.40, 95% CI 0.99 to 5.81), treatment discontinuation (RR 0.11, 95% CI 0.01 to 1.96), adverse events (RR 0.11, 95% CI 0.01 to 1.96) and relapses (21/38 relapsed) (RR 0.72, 95% CI 0.41 to 1.25) compared to standard interferon. In moderate certainty evidence, high-dose PEG interferon (alpha-2a and alpha-2b) may make little or no difference to death (2 studies, 97 participants: RR 4.30, 95% CI 0.76 to 24.33; I² = 0%), ETR (RR 1.42, 95% CI 0.51 to 3.90; I² = 20%), SVR (RR 1.19, 95% CI 0.68 to 2.07; I² = 0%), treatment discontinuation (RR 1.20, 95% CI 0.63 to 2.28; I² = 0%) or adverse events (RR 1.05, 95% CI 0.61 to 1.83; I² = 27%) compared to low-dose PEG interferon. High-dose PEG interferon may make little or no difference to relapses (1 study, 43 participants: RR 1.11, 95% CI 0.45 to 2.77; low certainty evidence). There were no significant subgroup differences. Standard interferon plus ribavirin may lead to higher treatment discontinuation (1 study, 52 participants: RR 2.97, 95% CI 1.19 to 7.36; low certainty evidence) compared to standard interferon alone.  In low certainty evidence, PEG interferon plus ribavirin (1 study, 377 participants) may improve SVR (RR 1.80, 95% CI 1.46 to 2.21), reduce relapses (RR 0.33, 95% CI 0.23 to 0.48), slightly increase the number with adverse events (RR 1.10, 95% CI 1.01 to 1.19), and may make little or no difference to ETR (RR 1.01, 95% CI 0.94 to 1.09) compared to PEG interferon alone. The evidence is very uncertain about the effect of PEG interferon plus ribavirin on treatment discontinuation (RR 1.71, 95% CI 0.69 to 4.24) compared to PEG interferon alone. One study reported grazoprevir plus elbasvir improved ETR (173 participants: RR 174.99, 95% CI 11.03 to 2775.78; low certainty evidence) compared to placebo. It is uncertain whether telaprevir plus ribavirin (high versus low initial dose) plus PEG interferon for 24 versus 48 weeks (1 study, 35 participants) improves ETR (RR 1.02, 95% CI 0.67 to 1.56) or SVR (RR 1.02, 95% CI 0.67 to 1.56) because the certainty of the evidence is very low.  Data on QoL, cost-effectiveness, cardiovascular outcomes and peritoneal dialysis were not available.

AUTHORS' CONCLUSIONS

In dialysis patients with HCV infection grazoprevir plus elbasvir probably improves ETR. There is no difference in ETR or SVR for combinations of telaprevir, ribavirin and PEG interferon given for different durations and doses. Though no longer in use, PEG interferon was more effective than standard interferon for ETR but not SVR. Increasing doses of PEG interferon did not improve responses. The addition of ribavirin to PEG interferon may result in fewer relapses, higher SVR, and higher numbers with adverse events.

Decision tree algorithm predicts hepatocellular carcinoma among chronic hepatitis C patients following viral eradication

Successful eradication of the hepatitis C virus (HCV) cannot eliminate the risk of hepatocellular carcinoma (HCC). Next-generation RNA sequencing provides comprehensive genomic insights into the pathogenesis of HCC. Artificial intelligence has opened a new era in precision medicine. This study integrated clinical features and genetic biomarkers to establish a machine learning-based HCC model following viral eradication. A prospective cohort of 55 HCV patients with advanced fibrosis, who achieved a sustained virologic response after antiviral therapy, was enrolled. The primary outcome was the occurrence of HCC. The genomic signatures of peripheral blood mononuclear cells (PBMC) were determined by RNA sequencing at baseline and 24 weeks after end-of-treatment. Machine learning algorithms were implemented to extract the predictors of HCC. HCC occurred in 8 of the 55 patients, with an annual incidence of 2.7%. Pretreatment PBMC DEFA1B, HBG2, ADCY4, and posttreatment TAS1R3, ABCA3, and FOSL1 genes were significantly downregulated, while the pretreatment ANGPTL6 gene was significantly upregulated in the HCC group compared to that in the non-HCC group. A gene score derived from the result of the decision tree algorithm can identify HCC with an accuracy of 95.7%. Gene score = TAS1R3 (≥0.63 FPKM, yes/no = 0/1) + FOSL1 (≥0.27 FPKM, yes/no = 0/1) + ABCA3 (≥2.40 FPKM, yes/no = 0/1). Multivariate Cox regression analysis showed that this gene score was the most important predictor of HCC (hazard ratio = 2.38, 95% confidence interval [CI] = 1.06-5.36, P = 0.036). Combining the gene score and fibrosis-4 index, a nomogram was constructed to predict the probability of HCC with an area under the receiver operating characteristic curve up to 0.950 (95% CI = 0.888-1.000, P = 7.0 × 10-5). Decision curve analysis revealed that the nomogram had a net benefit in HCC detection. The calibration curve showed that the nomogram had optimal concordance between the predicted and actual HCC probabilities. In conclusion, down-regulated posttreatment PBMC TAS1R3, ABCA3, and FOSL1 expression were significantly correlated with HCC development after HCV eradication. Decision-tree-based algorithms can refine the assessment of HCC risk for personalized HCC surveillance.

Dose-Dependent Hepacivirus Infection Reveals Linkage between Infectious Dose and Immune Response

More than 70 million people worldwide are still infected with the hepatitis C virus 30 years after its discovery, underscoring the need for a vaccine. To develop an effective prophylactic vaccine, detailed knowledge of the correlates of protection and an immunocompetent surrogate model are needed. In this study, we describe the minimum dose required for robust equine hepacivirus (EqHV) infection in equids and examined how this relates to duration of infection, seroconversion, and transcriptomic responses. To investigate mechanisms of hepaciviral persistence, immune response, and immune-mediated pathology, we inoculated eight EqHV naive horses with doses ranging from 1-2 copies to 1.3 × 106 RNA copies per inoculation. We characterized infection kinetics, pathology, and transcriptomic responses via next generation sequencing. The minimal infectious dose of EqHV in horses was estimated at 13 RNA copies, whereas 6 to 7 copies were insufficient to cause infection. Peak viremia did not correlate with infectious dose, while seroconversion and duration of infection appeared to be affected. Notably, seroconversion was undetectable in the low-dose infections within the surveillance period (40 to 50 days). In addition, transcriptomic analysis revealed a nearly dose-dependent effect, with greater immune activation and inflammatory response observed in high-dose infections than in low-dose infections. Interestingly, inoculation with 6-7 copies of RNA that did not result in productive infection, but was associated with a strong immune response, similar to that observed in the high-dose infections. IMPORTANCE We demonstrate that the EqHV dose of infection plays an important role for inducing immune responses, possibly linked to early clearance in high-dose and prolonged viremia in low-dose infections. In particular, pathways associated with innate and adaptive immune responses, as well as inflammatory responses, were more strongly upregulated in high-dose infections than in lower doses. Hence, inoculation with low doses may enable EqHV to evade strong immune responses in the early phase and therefore promote robust, long-lasting infection.

Severe Acute Hepatitis Outbreaks Associated with a Novel Hepacivirus in Rhizomys pruinosus in Hainan, China

Members of the genus Hepacivirus have a broad range of hosts, with at least 14 species identified. To date, a highly pathogenic hepacivirus causing severe disease in animals has not been found. Here, by using high-throughput sequencing, a new hepacivirus was identified as the dominant and highly pathogenic virus in severe acute hepatitis outbreaks in bamboo rats (Rhizomys pruinosus), with ≈80% mortality; this virus emerged in February 2020 in two bamboo rat farms in China. Hepaciviral genome copies in bamboo rat liver were significantly higher than in other organs. Genomic sequences of hepacivirus strains from 12 sick bamboo rats were found to share 85.3 to 100% nucleotide (nt) identity and 94.9 to 100% amino acid (aa) identity and to share 79.7 to 87.8% nt and 90.4 to 97.8% aa identities with previously reported bamboo rat hepaciviruses of Vietnam and China. Sequence analysis further revealed the simultaneous circulation of genetically divergent hepacivirus variants within the two outbreaks. Phylogenetic analysis showed that hepacivirus strains from the present and previous studies formed an independent clade comprised of at least two genotypes, clearly different from all other known species, suggesting a novel species within the genus Hepacivirus. This is the first report of a non-human-infecting hepacivirus causing potentially fatal infection of bamboo rats, and the associated hepatitis in the animals potentially can be used to develop a surrogate model for the study of hepatitis C virus infection in humans and for the development of therapeutic strategies. IMPORTANCE Members of the genus Hepacivirus have a broad host range, with at least 14 species identified, but none is highly pathogenic to its host except for hepatitis C virus, which causes severe liver diseases in humans. In this study, a new liver-tropic hepacivirus species was identified by high-throughput sequencing as the pathogen associated with two outbreaks of severely acute hepatitis in hoary bamboo rats (Rhizomys pruinosus) on two farms in Hainan Province, China; this is the first reported highly pathogenic animal hepacivirus to our knowledge. Further phylogenetic analysis suggested that the hepaciviruses derived from hoary bamboo rats in either the current or previous studies represent a novel species within the genus Hepacivirus. This finding is a breakthrough that has significantly updated our understanding about the pathogenicity of animal hepaciviruses, and the hepacivirus-associated hepatitis in bamboo rats may have a use as an animal infection model to understand HCV infection and develop therapeutic strategies.

Collaborative Referral Model to Achieve Hepatitis C Micro-Elimination in Methadone Maintenance Treatment Patients during the COVID-19 Pandemic

Although hepatitis C virus (HCV) prevails in patients receiving methadone maintenance treatment (MMT), most do not receive anti-HCV therapy. This single-center observational study aimed to achieve HCV micro-elimination at an MMT center during the COVID-19 pandemic using a collaborative referral model, which comprised a referral-for-diagnosis stage (January 2020 to August 2020) and an on-site-diagnosis stage (September 2020 to January 2021). A multidisciplinary team was established and all MMT center patients were enrolled. HCV micro-elimination was defined as >90% of HCV-infected patients diagnosed and >80% of HCV-viremic patients treated. A total of 305 MMT patients, including 275 (90.2%) anti-HCV seropositive patients, were enrolled. Among 189 HCV-infected patients needing referral, the accumulative percentage receiving HCV RNA testing increased from 93 (49.2%) at referral-for-diagnosis stage to 168 (88.9%) at on-site-diagnosis stage. Among 138 HCV-viremic patients, the accumulative percentage receiving direct-acting antiviral (DAA) therapy increased from 77 (55.8%) at referral-for-diagnosis stage to 129 (93.5%) at on-site-diagnosis stage. We achieved an HCV RNA testing rate of 92.4% (254/275), an HCV treatment rate of 95.8% (203/212) and a sustained virological response rate of 94.1% (191/203). The collaborative referral model is highly effective in HCV RNA testing and HCV treatment uptake among MMT patients, achieving HCV micro-elimination.

Undergraduate Medical School Health Fair Hepatitis Screenings: Utilizing Non-Profit Community Organizations

Background:

Undergraduate medical schools serve a critical role in providing screenings to medically underserved populations through the use of health fairs. Non-profit community organizations (NPCO) often participate by providing local credibility, administrative resources, and technical knowledge. Here we present a three-year narrative of hepatitis B and C screening efforts to highlight the challenges and benefits of undergraduate medical school and NPCO partnerships.

Methods:

Hepatitis screenings were conducted at biannual health fairs in Harlem, New York from 2017 to 2019. Meeting minutes from post-event debriefings were analyzed to identify any overarching themes with NPCOs.

Results:

NPCOs share a common goal in working with the community to advance their access to medical care and treatment. Communication and prompt follow-up are critical to maintaining expectations between NPCOs and health fair organizers.

Conclusions:

NPCOs can play an important role in encouraging, outreaching, and even managing hepatitis screening initiatives in conjunction with medical school health fairs.

Curative Therapies for Hepatitis C Virus Infection in Patients with Kidney Disease

Through the discovery of direct-acting antiviral therapies over the last decade, hepatitis C virus (HCV) has been transformed from a highly morbid and potentially fatal chronic viral infection to a curable illness. HCV is common in patients with kidney disease, is a risk factor for progression of CKD, is associated with higher morbidity and mortality in patients receiving dialysis, and leads to worse allograft and patient outcomes in recipients of kidney transplants. Clinical trial and real-world data of direct-acting antivirals in patients with kidney disease demonstrate extremely high cure rates and favorable adverse event profiles. This review covers the transformative effects of curative HCV therapies on patients with kidney disease, including patients with CKD, ESKD, and those who have received a kidney transplant.

Only partial improvement in health-related quality of life after treatment of chronic hepatitis C virus infection with direct acting antivirals in a real-world setting-results from the German Hepatitis C-Registry (DHC-R)

Improvement of health-related quality of life (HRQoL) is frequently reported as a benefit when treating hepatitis C virus infection (HCV) with direct acting antivirals (DAA). As most of the available data were obtained from clinical trials, limited generalizability to the real-world population might exist. This study aimed to investigate the impact of DAA therapy on changes in HRQoL in a real-world setting. HRQoL of 1180 participants of the German Hepatitis C-Registry was assessed by Short-Form 36 (SF-36) questionnaires. Scores at post-treatment weeks 12-24 (FU12/24) were compared to baseline (BL). Changes of ≥2.5 in mental and physical component summary scores (MCS and PCS) were defined as a minimal clinical important difference (MCID). Potential predictors of HRQoL changes were analysed. Overall, a statistically significant increase in HRQoL after DAA therapy was observed, that was robust among various subgroups. However, roughly half of all patients failed to achieve a clinically important improvement in MCS and PCS. Low MCS (p < .001, OR = 0.925) and PCS (p < .001, OR = 0.899) BL levels were identified as predictors for achieving a clinically important improvement. In contrast, presence of fatigue (p = .023, OR = 1.518), increased GPT levels (p = .005, OR = 0.626) and RBV containing therapy regimens (p = .001, OR = 1.692) were associated with a clinically important decline in HRQoL after DAA therapy. In conclusion, DAA treatment is associated with an overall increase of HRQoL in HCV-infected patients. Nevertheless, roughly half of the patients fail to achieve a clinically important improvement. Especially patients with a low HRQoL seem to benefit most from the modern therapeutic options.

A review of kidney transplantation from HCV-viremic donors into HCV-negative recipients

The safety and efficacy of direct-acting antiviral therapies have allowed the transplantation of organs from hepatitis C virus (HCV)-viremic donors into uninfected recipients. This novel strategy contrasts with the previous standard-of-care practice of limiting the transplantation of HCV infected-donor organs to HCV-infected recipients, or all too often, discarding viable organs. In this review, we summarize the published literature about the safety and feasibility of transplanting organs from HCV-viremic donors, the challenges that hinder wider adoption of this strategy, and future research needs.

All genera of Flaviviridae host a conserved Xrn1-resistant RNA motif

After infection by flaviviruses like Zika and West Nile virus, eukaryotic hosts employ the well-conserved endoribonuclease Xrn1 to degrade the viral genomic RNA. Within the 3' untranslated regions, this enzyme encounters intricate Xrn1-resistant structures. This results in the accumulation of subgenomic flaviviral RNAs, an event that improves viral growth and aggravates viral pathogenicity. Xrn1-resistant RNAs have been established throughout the flaviviral genus, but not yet throughout the entire Flaviviridae family. In this work, we use previously determined characteristics of these structures to identify homologous sequences in many members of the genera pegivirus, hepacivirus and pestivirus. We used structural alignment and mutational analyses to establish that these sequences indeed represent Xrn1-resistant RNA and that they employ the general features of the flaviviral xrRNAs, consisting of a double pseudoknot formed by five base-paired regions stitched together by a crucial triple base interaction. Furthermore, we demonstrate that the pestivirus Bungowannah virus produces subgenomic RNA in vivo. Altogether, these results indicate that viruses make use of a universal Xrn1-resistant RNA throughout the Flaviviridae family.

The Successful Treatment of a Case of HCV-associated Cryoglobulinemic Glomerulonephritis with Rituximab, Direct-acting Antiviral Agents, Plasmapheresis and Long-term Steroid Despite Serologically Persistent Cryoglobulinemia

Novel treatments with rituximab or direct-acting antiviral agents (DAAs) were expected to improve the clinical outcomes of hepatitis C virus (HCV)-associated cryoglobulinemia in the last decade. Recently, however, persistent cases of cryoglobulinemia have been reported, and the ideal approach to treating such cases has not been established. We herein report a case of the successful treatment of HCV-associated cryoglobulinemic glomerulonephritis with rituximab, DAAs, occasional plasmapheresis and long-term steroid, with the patient's renal function and proteinuria improving over the long term despite serologically persistent cryoglobulinemia. This case suggests the efficacy of combination treatment with rituximab, DAAs, occasional plasmapheresis and long-term steroid for persistent cryoglobulinemia.

Delayed by Design: Role of Suboptimal Signal Peptidase Processing of Viral Structural Protein Precursors in Flaviviridae Virus Assembly

The Flaviviridae virus family is classified into four different genera, including flavivirus, hepacivirus, pegivirus, and pestivirus, which cause significant morbidity and mortality in humans and other mammals, including ruminants and pigs. These are enveloped, single-stranded RNA viruses sharing a similar genome organization and replication scheme with certain unique features that differentiate them. All viruses in this family express a single polyprotein that encodes structural and nonstructural proteins at the N- and C-terminal regions, respectively. In general, the host signal peptidase cleaves the structural protein junction sites, while virus-encoded proteases process the nonstructural polyprotein region. It is known that signal peptidase processing is a rapid, co-translational event. Interestingly, certain signal peptidase processing site(s) in different Flaviviridae viral structural protein precursors display suboptimal cleavage kinetics. This review focuses on the recent progress regarding the Flaviviridae virus genus-specific mechanisms to downregulate signal peptidase-mediated processing at particular viral polyprotein junction sites and the role of delayed processing at these sites in infectious virus particle assembly.

Novel hepaci- and pegi-like viruses in native Australian wildlife and non-human primates

The Flaviviridae family of positive-sense RNA viruses contains important pathogens of humans and other animals, including Zika virus, dengue virus, and hepatitis C virus. The Flaviviridae are currently divided into four genera-Hepacivirus, Pegivirus, Pestivirus, and Flavivirus-each with a diverse host range. Members of the genus Hepacivirus are associated with an array of animal species, including humans, non-human primates, other mammalian species, as well as birds and fish, while the closely related pegiviruses have been identified in a variety of mammalian taxa, also including humans. Using a combination of total RNA and whole-genome sequencing we identified four novel hepaci-like viruses and one novel variant of a known hepacivirus in five species of Australian wildlife. The hosts infected comprised native Australian marsupials and birds, as well as a native gecko (Gehyra lauta). From these data we identified a distinct marsupial clade of hepaci-like viruses that also included an engorged Ixodes holocyclus tick collected while feeding on Australian long-nosed bandicoots (Perameles nasuta). Distinct lineages of hepaci-like viruses associated with geckos and birds were also identified. By mining the SRA database we similarly identified three new hepaci-like viruses from avian and primate hosts, as well as two novel pegi-like viruses associated with primates. The phylogenetic history of the hepaci- and pegi-like viruses as a whole, combined with co-phylogenetic analysis, provided support for virus-host co-divergence over the course of vertebrate evolution, although with frequent cross-species virus transmission. Overall, our work highlights the diversity of the Hepacivirus and Pegivirus genera as well as the uncertain phylogenetic distinction between.

Genetic heterogeneity of bovine hepacivirus in Italy

Viruses similar to human hepatitis C virus (HCV) in the Hepacivirus genus have been identified in several animal hosts, including cattle. Since its first discovery in Germany, bovine hepacivirus (BovHepV) has been described in several countries globally. However, limited data are available on BovHepV epidemiology and genetic variability. The aim of this study was to investigate the prevalence and genetic diversity of BovHepV in Italy. Viral RNA was identified in 37 (0.15%) of 24,820 bovine sera, with titres ranging from 1.09 × 10³ to 8.27 × 10⁶ RNA copies/ml. Upon sequencing and phylogenetic analysis of the 5'UTR and NS3 genomic portions, the Italian BovHepV strains segregated into at least four distinct subtypes (A, B, C and F) that are also co-circulating globally.

Priming of Antiviral CD8 T Cells without Effector Function by a Persistently Replicating Hepatitis C-Like Virus

Immune-competent animal models for the hepatitis C virus (HCV) are nonexistent, impeding studies of host-virus interactions and vaccine development. Experimental infection of laboratory rats with a rodent hepacivirus isolated from Rattus norvegicus (RHV) is a promising surrogate model due to its recapitulation of HCV-like chronicity. However, several aspects of rat RHV infection remain unclear, for instance, how RHV evades host adaptive immunity to establish persistent infection. Here, we analyzed the induction, differentiation, and functionality of RHV-specific CD8 T cell responses that are essential for protection against viral persistence. Virus-specific CD8 T cells targeting dominant and subdominant major histocompatibility complex class I epitopes proliferated considerably in liver after RHV infection. These populations endured long term yet never acquired antiviral effector functions or selected for viral escape mutations. This was accompanied by the persistent upregulation of programmed cell death-1 and absent memory cell formation, consistent with a dysfunctional phenotype. Remarkably, transient suppression of RHV viremia with a direct-acting antiviral led to the priming of CD8 T cells with partial effector function, driving the selection of a viral escape variant. These data demonstrate an intrinsic abnormality within CD8 T cells primed by rat RHV infection, an effect that is governed at least partially by the magnitude of early virus replication. Thus, this model could be useful in investigating mechanisms of CD8 T cell subversion, leading to the persistence of hepatotropic pathogens such as HCV.IMPORTANCE Development of vaccines against hepatitis C virus (HCV), a major cause of cirrhosis and cancer, has been stymied by a lack of animal models. The recent discovery of an HCV-like rodent hepacivirus (RHV) enabled the development of such a model in rats. This platform recapitulates HCV hepatotropism and viral chronicity necessary for vaccine testing. Currently, there are few descriptions of RHV-specific responses and why they fail to prevent persistent infection in this model. Here, we show that RHV-specific CD8 T cells, while induced early at high magnitude, do not develop into functional effectors capable of controlling virus. This defect was partially alleviated by short-term treatment with an HCV antiviral. Thus, like HCV, RHV triggers dysfunction of virus-specific CD8 T cells that are vital for infection resolution. Additional study of this evasion strategy and how to mitigate it could enhance our understanding of hepatotropic viral infections and lead to improved vaccines and therapeutics.

Replicons of a Rodent Hepatitis C Model Virus Permit Selection of Highly Permissive Cells

Animal hepaciviruses represent promising surrogate models for hepatitis C virus (HCV), for which there are no efficient immunocompetent animal models. Experimental infection of laboratory rats with rodent hepacivirus isolated from feral Rattus norvegicus (RHV-rn1) mirrors key aspects of HCV infection in humans, including chronicity, hepatitis, and steatosis. Moreover, RHV has been adapted to infect immunocompetent laboratory mice. RHV in vitro systems have not been developed but would enable detailed studies of the virus life cycle crucial for designing animal experiments to model HCV infection. Here, we established efficient RHV-rn1 selectable subgenomic replicons with and without reporter genes. Rat and mouse liver-derived cells did not readily support the complete RHV life cycle, but replicon-containing cell clones could be selected with and without acquired mutations. Replication was significantly enhanced by mutations in NS4B and NS5A and in cell clones cured of replicon RNA. These mutations increased RHV replication of both mono- and bicistronic constructs, and CpG/UpA-dinucleotide optimization of reporter genes allowed replication. Using the replicon system, we show that the RHV-rn1 NS3-4A protease cleaves a human mitochondrial antiviral signaling protein reporter, providing a sensitive readout for virus replication. RHV-rn1 replication was inhibited by the HCV polymerase inhibitor sofosbuvir and high concentrations of HCV NS5A antivirals but not by NS3 protease inhibitors. The microRNA-122 antagonist miravirsen inhibited RHV-rn1 replication, demonstrating the importance of this HCV host factor for RHV. These novel RHV in vitro systems will be useful for studies of tropism, molecular virology, and characterization of virus-host interactions, thereby providing important complements to in vivo systems.IMPORTANCE A vaccine against hepatitis C virus (HCV) is crucial for global control of this important pathogen, which induces fatal human liver diseases. Vaccine development has been hampered by the lack of immunocompetent animal models. Discovery of rodent hepacivirus (RHV) enabled establishment of novel surrogate animal models. These allow robust infection and reverse genetic and immunization studies of laboratory animals, which develop HCV-like chronicity. Currently, there are no RHV in vitro systems available to study tropism and molecular virology. Here, we established the first culture systems for RHV, recapitulating the intracellular phase of the virus life cycle in vitro These replicon systems enabled identification of replication-enhancing mutations and selection of cells highly permissive to RHV replication, which allow study of virus-host interactions. HCV antivirals targeting NS5A, NS5B, and microRNA-122 efficiently inhibited RHV replication. Hence, several important aspects of HCV replication are shared by the rodent virus system, reinforcing its utility as an HCV model.

A highly divergent hepacivirus-like flavivirus in domestic ducks

Using random amplification and reverse transcription-PCR, a novel RNA virus was detected in sera of domestic ducks. The full genome of the virus was determined for three strains, identifying the first hepacivirus-like flavivirus in birds. The virus, that we tentatively named duck hepacivirus-like virus (DuHV), possesses several unique molecular features, such as possession of the largest hepacivirus-like polyprotein gene and a Pegivirus A-like internal ribosome entry site. Sequence comparisons and phylogenetic and sliding-window analyses indicated that DuHV is most closely related to, but highly divergent from, the known hepaciviruses. DuHV was detected in 69.7 % of 185 serum samples from four duck species and in 31 of 33 flocks from five provinces of China, reflecting a high prevalence in duck populations and a wide geographical distribution. The detection of DuHV in the same flock in November 2018 and April 2019 suggested that persistent infection can be established in the infected ducks.

Daclatasvir and reduced-dose sofosbuvir: An effective and pangenotypic treatment for hepatitis C in patients with estimated glomerular filtration rate <30 mL/min

AIM

Sofosbuvir is a key agent for HCV treatment. It is not recommended for patients with chronic kidney disease (CKD) and estimated glomerular filtration rate (eGFR) <30 mL/min. We report real-life experience of treating a cohort of CKD patients with eGFR <30 mL/min using daclatasvir and half-daily dose of sofosbuvir.

METHODS

Adults patients who (i) had eGFR<30 mL/min and detectable HCV RNA and (ii) were treated with interferon and ribavirin free, DAA based regimens were included. All patients were treated with daily doses of daclatasvir 60 mg and sofosbuvir 200 mg. The planned duration of treatment was 12 weeks, except for 24 weeks in those with either clinical evidence of cirrhosis or on immunosuppressive drugs. The end-points of the study were: (i) 12 weeks of follow-up after treatment completion, (ii) treatment discontinuation, or (iii) death or loss to follow-up.

RESULTS

Thirty-six (88%) among 41 included patients (median [range] age: 48 [19-75] years; 25 [61%] male; genotype 1/3/4 were 17/ 22/2; cirrhosis 5) completed the treatment, two discontinued and three died during treatment. On an intention-to-treat basis, HCV RNA were undetectable at 4 weeks of treatment, treatment completion and after 12 weeks of follow-up in 40/41 (97.6%), 37/41 (90.2%) and 37/41 (90.2%), respectively. None of the patients had a relapse.

CONCLUSIONS

Daclatasvir and half-daily dose of sofosbuvir was effective against genotype 1 and 3 HCV infection in patients with eGFR <30 mL/min. This combination could be a pangenotypic treatment option for such patients.

The prevalence of elevated gamma-glutamyltransferase and sorbitol dehydrogenase activity in racing Thoroughbreds and their associations with viral infection

BACKGROUND

In racehorses, serum gamma-glutamyltransferase (GGT) activity is positively correlated with cumulative days in training and, when ≥100 IU/L, has been associated with poor performance. The prevalence of increased GGT activity in North American Thoroughbreds and its aetiopathogenesis are unknown. Four emerging viruses, pegivirus E (PgV E; equine pegivirus), hepacivirus A (HcV A; equine hepacivirus), pegivirus D (PgV D; Theiler's disease virus), and equine parvovirus-hepatitis (EqPV-H) have been identified in horses with clinical and subclinical hepatopathy. Available prevalence data indicate these viruses may commonly infect racehorses and contribute to increased liver enzyme activity in this population.

OBJECTIVES

To investigate the association between viral infection and increased liver enzyme activity in racing Thoroughbreds.

STUDY DESIGN

Cross-sectional study.

METHODS

Prerace blood samples were collected from 802 Thoroughbreds and tested for GGT and sorbitol dehydrogenase (SDH) activity, and the presence of PgV E, HcV A, PgV D and EqPV-H nucleic acid.

RESULTS

Increased SDH and/or GGT were detected in 56.2% of the 802 serum samples. The infection prevalence and relative risk (RR) of having concurrently increased liver enzyme activity were: PgV E = 18.2% (RR = 0.820, 95% CI = 0.662-0.978, P = 0.03), HcV A = 2.5% (RR = 1.132, 95% CI = 0.719-1.466, P = 0.6), PgV D = 0.5% (RR = 0.875, 95% CI = 0.165-1.598, P>0.9), EqPV-H = 2.9% (RR = 0.916, 95% CI = 0.564-1.266, P = 0.7).

MAIN LIMITATIONS

Longitudinal samples were not tested.

CONCLUSIONS

While viral infection was common among Thoroughbreds in this study, infection did not explain the high prevalence of increased liver enzyme activity. In fact, PgV E infection was associated with a reduced risk of having increased liver enzyme activity, indicating PgV E is unlikely to be a cause of hepatitis in horses. Importantly, like GGT, increased SDH activity was highly prevalent in this study, and provides additional evidence that hepatocellular injury was occurring in these horses.

The Small-Compound Inhibitor K22 Displays Broad Antiviral Activity against Different Members of the Family Flaviviridae and Offers Potential as a Panviral Inhibitor

The virus family Flaviviridae encompasses several viruses, including (re)emerging viruses which cause widespread morbidity and mortality throughout the world. Members of this virus family are positive-strand RNA viruses and replicate their genome in close association with reorganized intracellular host cell membrane compartments. This evolutionarily conserved strategy facilitates efficient viral genome replication and contributes to evasion from host cell cytosolic defense mechanisms. We have previously described the identification of a small-compound inhibitor, K22, which exerts a potent antiviral activity against a broad range of coronaviruses by targeting membrane-bound viral RNA replication. To analyze the antiviral spectrum of this inhibitor, we assessed the inhibitory potential of K22 against several members of the Flaviviridae family, including the reemerging Zika virus (ZIKV). We show that ZIKV is strongly affected by K22. Time-of-addition experiments revealed that K22 acts during a postentry phase of the ZIKV life cycle, and combination regimens of K22 together with ribavirin (RBV) or interferon alpha (IFN-α) further increased the extent of viral inhibition. Ultrastructural electron microscopy studies revealed severe alterations of ZIKV-induced intracellular replication compartments upon infection of K22-treated cells. Importantly, the antiviral activity of K22 was demonstrated against several other members of the Flaviviridae family. It is tempting to speculate that K22 exerts its broad antiviral activity against several positive-strand RNA viruses via a similar mechanism and thereby represents an attractive candidate for development as a panviral inhibitor.

Further characterization of bovine hepacivirus: Antibody response, course of infection, and host tropism

Bovine hepacivirus (BovHepV) is a recently added member to the growing genus Hepacivirus within the family Flaviviridae. Animal hepaciviruses are rarely characterized so far. Apart from norway rat hepacivirus which represents a promising HCV surrogate model, only equine hepaciviruses have been studied to some extent. BovHepV has been initially identified in bovine samples and was shown to establish persistent infections in cattle. However, consequences of those chronic infections, humoral immune response and the possibility of an extended host spectrum have not been explored so far. Therefore, we here investigated (a) the presence of anti-NS3-antibodies and viral RNA in cattle herds in Germany, (b) the course of infection in cattle, and (c) the host tropism including zoonotic potential of bovine hepaciviruses. Our results show that 19.9% of investigated bovine serum samples had antibodies against BovHepV. In 8.2% of investigated samples, viral RNA was detected. Subsequent genetic analysis revealed a novel genetic cluster of BovHepV variants. For 25 selected cattle in a BovHepV positive herd the presence of viral genomic RNA was monitored over one year in two to three months intervals by RT-PCR in order to discriminate acute versus persistent infection. In persistently infected animals, no serum antibodies were detected. Biochemical analyses could not establish a link between BovHepV infection and liver injury. Apart from a single sample of a pig providing a positive reaction in the antibody test, neither BovHepV-specific antibodies nor viral RNA were detected in porcine, equine or human samples implying a strict host specificity of BovHepV.

Hepacivirus A Infection in Horses Defines Distinct Envelope Hypervariable Regions and Elucidates Potential Roles of Viral Strain and Adaptive Immune Status in Determining Envelope Diversity and Infection Outcome

Hepacivirus A (also known as nonprimate hepacivirus and equine hepacivirus) is a hepatotropic virus that can cause both transient and persistent infections in horses. The evolution of intrahost viral populations (quasispecies) has not been studied in detail for hepacivirus A, and its roles in immune evasion and persistence are unknown. To address these knowledge gaps, we first evaluated the envelope gene (E1 and E2) diversity of two different hepacivirus A strains (WSU and CU) in longitudinal blood samples from experimentally infected adult horses, juvenile horses (foals), and foals with severe combined immunodeficiency (SCID). Persistent infection with the WSU strain was associated with significantly greater quasispecies diversity than that observed in horses who spontaneously cleared infection (P = 0.0002) or in SCID foals (P < 0.0001). In contrast, the CU strain was able to persist despite significantly lower (P < 0.0001) and relatively static envelope diversity. These findings indicate that envelope diversity is a poor predictor of hepacivirus A infection outcomes and could be dependent on strain-specific factors. Next, entropy analysis was performed on all E1/E2 genes entered into GenBank. This analysis defined three novel hypervariable regions (HVRs) in E2, at residues 391 to 402 (HVR1), 450 to 461 (HVR2), and 550 to 562 (HVR3). For the experimentally infected horses, entropy analysis focusing on the HVRs demonstrated that these regions were under increased selective pressure during persistent infection. Increased diversity in the HVRs was also temporally associated with seroconversion in some horses, suggesting that these regions may be targets of neutralizing antibody and may play a role in immune evasion.IMPORTANCE Hepacivirus C (hepatitis C virus) is estimated to infect 150 million people worldwide and is a leading cause of cirrhosis and hepatocellular carcinoma. In contrast, its closest relative, hepacivirus A, causes relatively mild disease in horses and is frequently cleared. The relationship between quasispecies evolution and infection outcome has not been explored for hepacivirus A. To address this knowledge gap, we examined envelope gene diversity in horses with resolving and persistent infections. Interestingly, two strain-specific patterns of quasispecies diversity emerged. Persistence of the WSU strain was associated with increased quasispecies diversity and the accumulation of amino acid changes within three novel hypervariable regions following seroconversion. These findings provided evidence that envelope gene mutation is influenced by adaptive immune pressure and may contribute to hepacivirus persistence. However, the CU strain persisted despite relative evolutionary stasis, suggesting that some hepacivirus strains may use alternative mechanisms to persist in the host.

Presence of two different bovine hepacivirus clusters in Germany

During the last years, genetic information of hepaciviruses (family Flaviviridae), whose type species is the human hepatitis C virus, was detected in a wide range of primates and non-primate vertebrates. Here, samples collected from 263 German cattle kept in 22 different holdings were analysed for the presence of hepacivirus N (syn. bovine hepacivirus; BovHepV). One hundred eighty-six cattle that suffered from unspecific clinical signs such as fever and a reduced milk yield as well as 77 apparently healthy animals were included. A total of 39 cattle (14.8%) tested positive for BovHepV by real-time RT-PCR, but a correlation between clinical signs and virus infection could not be found. From 31 of the virus-positive samples, sequences of the NS3 coding region were generated and from two samples, viral sequences of the complete coding region were produced and compared to further European and African BovHepV sequences. Based on the NS3 genomic region, two distinct German BovHepV clusters were identified which differed between each other up to 20% at the nucleotide level, the diversity within the individual clusters reached up to 10%. Based on the full-length sequences, the newly detected virus variants group together with further German and African viruses in a sister relationship to other hepaciviruses from primates and further mammalians, but form distinct clusters within the BovHepV branch. In conclusion, highly diverse hepaciviruses were detected in German cattle further expanding the known phylogenetic diversity of the genus Hepacivirus.

Fraction and incidence of liver cancer attributable to hepatitis B and C viruses worldwide

High-quality data on liver cancers by probable cause are scarce in many regions of the world. The United Nations recently set a goal of eliminating viral hepatitis as a major public health threat by 2030. We aimed to estimate the number of new cases of cancers attributable to hepatitis B virus (HBV) and hepatitis C virus (HCV) at a global, regional and country level, and by development status. We used data on the prevalence of HBV and HCV in hepatocellular carcinoma from a systematic review including 119,000 cases in 260 studies covering 50 countries. A statistical model was constructed to extrapolate empirical data to countries without prevalence data. Country-specific numbers of liver cancer cases attributable to HBV and HCV were calculated using data from GLOBOCAN 2012. Globally, 770,000 cases of liver cancer occurred worldwide in 2012, of which 56% (95% CI: 52-60) were attributable to HBV and 20% (95% CI: 18-22) to HCV. Currently, HBV causes approximately two out of three cases of liver cancer in less developed countries but one in four cases in more developed countries and shows a much higher degree of geographical aggregation in Eastern Asia and sub-Saharan Africa than HCV. These estimates help set priorities for liver cancer prevention. High-coverage HBV vaccination will be transformational in HBV-endemic countries but the prevention of HCV transmission and the treatment of chronic carriers of both viruses requires new scalable solutions.

Roles of the 5' Untranslated Region of Nonprimate Hepacivirus in Translation Initiation and Viral Replication

The 5' untranslated region (UTR) of hepatitis C virus (HCV), which is composed of four domains (I, II, III, and IV) and a pseudoknot, is essential for translation and viral replication. Equine nonprimate hepacivirus (EHcV) harbors a 5' UTR consisting of a large 5'-terminal domain (I); three additional domains (I', II, and III), which are homologous to domains I, II, and III, respectively, of HCV; and a pseudoknot, in the order listed. In this study, we investigated the roles of the EHcV 5' UTR in translation and viral replication. The internal ribosome entry site (IRES) activity of the EHcV 5' UTR was lower than that of the HCV 5' UTR in several cell lines due to structural differences in domain III. Domains I and III of EHcV were functional in the HCV 5' UTR in terms of IRES activity and the replication of the subgenomic replicon (SGR), although domain II was not exchangeable between EHcV and HCV for SGR replication. Furthermore, the region spanning domains I and I' of EHcV (the 5'-proximal EHcV-specific region) improved RNA stability and provided the HCV SGR with microRNA 122 (miR-122)-independent replication capability, while EHcV domain I alone improved SGR replication and RNA stability irrespective of miR-122. These data suggest that the region spanning EHcV domains I and I' improves RNA stability and viral replication regardless of miR-122 expression. The 5'-proximal EHcV-specific region may represent an inherent mechanism to facilitate viral replication in nonhepatic tissues.IMPORTANCE EHcV is the closest viral homolog to HCV among other hepaciviruses. HCV exhibits a narrow host range and liver-specific tropism, while epidemiological reports suggest that EHcV infects the liver and respiratory organs in horses, donkeys, and dogs. However, the mechanism explaining the differences in host or organ tropism between HCV and EHcV is unknown. In this study, our data suggest that the 5' untranslated region (UTR) of EHcV is composed of an internal ribosome entry site (IRES) element that is functionally exchangeable with HCV IRES elements. Furthermore, the 5'-proximal EHcV-specific region enhances viral replication and RNA stability in a miR-122-independent manner. Our data suggest that the region upstream of domain II in the EHcV 5' UTR contributes to the differences in tissue tropism observed between these hepaciviruses.

Extrahepatic manifestations associated with Chronic Hepatitis C Virus Infection

Chronic hepatitis C virus (HCV) infection has been associated with both organ-specific and systemic autoimmune diseases, with cryoglobulinemia being the most frequent associated disease. Experimental, virologic, and clinical evidence have demon-strated a close association between HCV infection and some systemic autoimmune diseases, especially Sjögren's syndrome, but also rheumatoid arthritis and lupus. A higher prevalence of hematological processes has also been described in patients with HCV infection, including cytopenias and lymphoproliferative disorders (B-cell lymphoma). In addition, patients with chronic HCV infection have a higher frequency of other extrahepatic manifestations including endocrine, metabolic and cardiovascular disorders that may worse the prognosis of patients, along with neuropsychiatric manifestations and general symptoms that have a significant influence on the quality of life of the patient. Direct-acting antiviral therapies (DAAs) that have recently begun to be used are providing the opportunity to effectively cure chronic HCV infection and reduce the burden of both hepatic and extrahepatic complications.

Knowledge, attitude and behaviour regarding hepatitis C virus infection amongst Brazilian dental students

AIM

Dental health professionals, including dental students, are at high risk of exposure to infection with the hepatitis C virus (HCV) through occupational percutaneous injuries and eye exposure. Further, fear of HCV infection is associated with discriminatory attitudes. The current study aimed to evaluate the knowledge about HCV infection amongst dental students and their attitudes towards patients infected with HCV.

METHODS

A cross-sectional survey was conducted amongst 340 Brazilian dental students from two public universities using an instrument containing information regarding demographic characteristics, knowledge of HCV and attitudes towards patients with HCV infection. Descriptive statistics, Fisher's exact test, Student's t-tests, Mann-Whitney U-test and multiple logistic regression (MLR) were carried out (P < 0.05 was considered significant).

RESULTS

Response rate was 90% (n = 306), and more than half (54%, n = 165) of participants had high knowledge level (above the mean); 97.7% (n = 299) demonstrated positive attitudes. MLR showed that high knowledge of dental students regarding HCV was substantially influenced by advancement in year of study (last year; P < 0.001) and type of university (federal; P = 0.049). Positive attitude towards HCV-infected patients was mainly influenced by age (P = 0.004) and male gender (P = 0.022).

CONCLUSIONS

These results demonstrated a satisfactory knowledge about HCV infection amongst dental students, but some gaps were observed, suggesting the importance of continuous education about HCV in this population to prevent HCV infection as well as discrimination and prejudice towards patients with hepatitis C.

Equine hepacivirus persistent infection in a horse with chronic wasting

Equine hepacivirus is the closest homologue of hepatitis C virus. Limited data on the clinical features of this infection are available. We report the identification of a horse with high-titre viremia by equine hepacivirus. Over a 15-month follow-up, the clinical signs and the viremic status persisted, suggesting a chronic evolution.

[Hepatitis C virus genotypes circulating in Colombia]

INTRODUCTION

Chronic hepatitis C virus infection is a worldwide public health problem; it has been estimated that over 180 million people are infected with this virus worldwide. Its precise incidence and prevalence (i.e., epidemiology) and the most frequent circulating genotypes in Colombia are unknown.

OBJECTIVE

To describe the hepatitis C virus (HCV) genotypes and subtypes in infected Colombian patients.

MATERIALS AND METHODS

We recovered the data on 1,538 HCV isolates from 1,527 patients in two Colombian reference laboratories typed by PAGE or qPCR.

RESULTS

Patients' mean age was 53 years; 70% of them were 40 to 70 years old, and 52%, females; 57% of all tests were ordered in Bogotá and 80% of cases were from Cundinamarca, Valle and Atlántico departments. Genotype 1 was detected in 88.6% of cases, distributed as follows: 70% subtype 1b, 13.5% subtype 1a and 5.1%, undetermined subtypes. Genotype 2 was found in 5.4% of the patients, genotype 3 in 2% and genotype 4 in 4%. Mixed genotypes were found in 0.8% of the samples.

CONCLUSION

Genotype 1 is the most common HCV genotype circulating in Colombia, and subtype 1b the most frequent.

Prevalence of Equine Hepacivirus Infections in France and Evidence for Two Viral Subtypes Circulating Worldwide

Like hepatitis C virus (HCV) in humans, the newly identified equine hepacivirus (NPHV) displays a predominating liver tropism that may evolve into chronic infections. The genomes of the two viruses share several organizational and functional features and are phylogenetically closest amongst the Hepacivirus genus. A limited amount of data is available regarding the spread of hepacivirus infections in horses. In this study, we asked whether in a more representative sample the prevalence and distribution of NPHV infections in France would resemble that reported so far in other countries. A total of 1033 horses sera from stud farms throughout France were analysed by qRT-PCR to determine the prevalence of ongoing NPHV infections and viral loads; in positive samples, partial sequences of NPHV's genome (5'UTR, NS3 and NS5B genes) were determined. Serum concentrations of biliary acids, glutamate dehydrogenase (GLDH) and L-gamma-glutamyl transferase (γ-GT) were measured for most horses. We detected NPHV infections in 6.2% of the horses, a prevalence that reached 8.3% in thoroughbreds and was significantly higher than in other breeds. The presence of circulating virus was neither significantly associated with biological disturbances nor with clinical hepatic impairment. Our phylogenetic analysis was based on both neighbour-joining and maximum-likelihood approaches. Its result shows that, like almost everywhere else in the world so far, two major groups of NPHV strains infect French domestic horses. Based on genetic distances, we propose a classification into two separate NPHV subtypes. Viral loads in the serum of horses infected by the main subtype were, in average, four times higher than in those infected by the second subtype. We hypothesize that amino acid substitutions in the palm domain of NS5B between NPHV subtypes could underlie viral phenotypes that explain this result.

[Natural reservoirs of viruses of the genus Hepacivirus, Flaviviridae]

HCV is a cause of acute and chronic liver diseases, including chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Under natural conditions, HCV is able to infect only humans, and only chimpanzees are sensitive to experimental infection. In recent years, viruses genetically related to HCV were discovered in wild mammals (rodents, bats, rabbits), as well as in domestic animals living in close contact with humans (dogs, horses, cows). The hepacivirus genus of the family Flaviviridae, previously represented only by HCV and, presumably, by GBV-B, now includes new related viruses of animals. The results of the study of molecular-genetic and biological properties of the hepaciviruses provide an opportunity to understand the history, evolution, and the origin of HCV. It also opens up the prospect of using HCV homologues of non-primates as a laboratory model for preclinical medical and prophylactic drugs against hepatitis c. It was found that the hepacivirus of horses is the most closely related to HCV among currently known HCV homologues.

Non-primate hepacivirus infection with apparent hepatitis in a horse - Short communication

Non-primate hepacivirus (NPHV) is a recently identified hepacivirus (family Flaviviridae) in dog and horse; however, the disease associations remain unknown. This study reports the detection of natural NPHV infection in a horse with apparent hepatitis, liver damage and high-level viraemia. NPHV could be hepatotropic and associated with hepatitis in horses.

Unfolded protein response in hepatitis C virus infection

Hepatitis C virus (HCV) is a single-stranded, positive-sense RNA virus of clinical importance. The virus establishes a chronic infection and can progress from chronic hepatitis, steatosis to fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). The mechanisms of viral persistence and pathogenesis are poorly understood. Recently the unfolded protein response (UPR), a cellular homeostatic response to endoplasmic reticulum (ER) stress, has emerged to be a major contributing factor in many human diseases. It is also evident that viruses interact with the host UPR in many different ways and the outcome could be pro-viral, anti-viral or pathogenic, depending on the particular type of infection. Here we present evidence for the elicitation of chronic ER stress in HCV infection. We analyze the UPR signaling pathways involved in HCV infection, the various levels of UPR regulation by different viral proteins and finally, we propose several mechanisms by which the virus provokes the UPR.

Natural reservoirs for homologs of hepatitis C virus

Hepatitis C virus is considered a major public health problem, infecting 2%–3% of the human population. Hepatitis C virus infection causes acute and chronic liver disease, including chronic hepatitis, cirrhosis and hepatocellular carcinoma. In fact, hepatitis C virus infection is the most frequent indication for liver transplantation and a vaccine is not available. Hepatitis C virus displays a narrow host species tropism, naturally infecting only humans, although chimpanzees are also susceptible to experimental infection. To date, there is no evidence for an animal reservoir of viruses closely related to hepatitis C virus which may have crossed the species barrier to cause disease in humans and resulted in the current pandemic. In fact, due to this restricted host range, a robust immunocompetent small animal model is still lacking, hampering mechanistic analysis of virus pathogenesis, immune control and prophylactic vaccine development. Recently, several studies discovered new viruses related to hepatitis C virus, belonging to the hepaci- and pegivirus genera, in small wild mammals (rodents and bats) and domesticated animals which live in close contact with humans (dogs and horses). Genetic and biological characterization of these newly discovered hepatitis C virus-like viruses infecting different mammals will contribute to our understanding of the origins of hepatitis C virus in humans and enhance our ability to study pathogenesis and immune responses using tractable animal models. In this review article, we start with an introduction on the genetic diversity of hepatitis C virus and then focus on the newly discovered viruses closely related to hepatitis C virus. Finally, we discuss possible theories about the origin of this important viral human pathogen.

Quantification of hepatic FOXP3+ T-lymphocytes in HIV/hepatitis C coinfection

Coinfection with HIV adversely impacts every stage of hepatitis C (HCV) infection. Liver damage in HCV infection results from host antiviral responses rather than direct viral pathogenesis. Despite depressed cellular immunity, coinfected patients show accelerated hepatic fibrosis compared with HCV monoinfected patients. This paradox is poorly understood. T-regulatory (Treg) cells (CD4+ and FOXP3+) are hypothesized to limit hepatic damage in HCV. Our hypothesis was that reduced frequency of hepatic Treg in HIV/HCV coinfection compared with HCV monoinfection may explain poorer outcomes. We quantified FOXP3+, CD4+, CD8+ and CD20+ cells in liver biopsies of 35 male subjects matched by age and ISHAK fibrosis score, 12 HIV monoinfected, 11 HCV monoinfected and 12 HIV/HCV coinfected. Cell counts were performed using indirect immunohistochemical staining and light microscopy. HIV/HCV coinfected subjects had fewer hepatic FOXP3+ (P = 0.031) and CD4+ cells (P = 0.001) than HCV monoinfected subjects. Coinfected subjects had more hepatic CD8+ cells compared with HCV monoinfected (P = 0.023), and a lower ratio of FOXP3+ to CD8+ cells (0.08 vs 0.27, P < 0.001). Multivariate analysis showed number of CD4+ cells controlled for differences in number of FOXP3+ cells. Fewer hepatic FOXP3+ and CD4+ cells in HIV/HCV coinfection compared with HCV monoinfection suggests lower Treg activity, driven by an overall loss of CD4+ cells. Higher number of CD8+ cells in HIV/HCV coinfection suggests higher cytotoxic activity. This may explain poorer outcomes in HIV/HCV coinfected patients and suggests a potential mechanism by which highly active antiretroviral therapy may benefit these patients.

A novel membrane fusion protein family in Flaviviridae?

Enveloped viruses must fuse their lipid membrane to a cellular membrane to deliver their genome into the cytoplasm for replication. Viral envelope proteins catalyze this critical membrane fusion event. They fall into three distinct structural classes. In 2013, envelope proteins from a pestivirus and hepatitis C virus were found to have two distinct novel folds. This was unexpected because these viruses are in the same family as flaviviruses, which have class II fusion proteins. We propose that the membrane fusion machinery of the closely related pestiviruses and hepatitis C virus defines a new structural class. This and other recently identified structural relationships between viral fusion proteins shift the paradigm for how these proteins evolved.

Antiviral prophylaxis for the prevention of chronic hepatitis C virus in patients undergoing liver transplantation

BACKGROUND

It is not clear whether prophylactic antiviral therapy is indicated to improve patient and graft survival in patients undergoing liver transplantation for chronic decompensated hepatitis C virus (HCV) infection.

OBJECTIVES

To compare the benefits and harms of different prophylactic antiviral therapies for patients undergoing liver transplantation for chronic HCV infection.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; Issue 1, 2013), MEDLINE, EMBASE, and Science Citation Index Expanded to February 2013.

SELECTION CRITERIA

Only randomised clinical trials irrespective of language, blinding, or publication status and comparing various prophylactic antiviral therapies (alone or in combination) in the prophylactic treatment of patients undergoing liver transplantation for chronic HCV infection.

DATA COLLECTION AND ANALYSIS

Two authors collected the data independently. We calculated the risk ratio (RR) or mean difference (MD) or hazard ratio (HR) with 95% confidence intervals (CI) using the fixed-effect and the random-effects models based on available case analysis.

MAIN RESULTS

A total of 501 liver transplant recipients undergoing liver transplantation for chronic HCV infection were randomised in 12 trials to various experimental interventions and control interventions. The proportion of genotype I varied between 49% and 100% in the seven trials that reported the genotype. Only one or two trials were included under each comparison. All the trials were of high risk of bias. Ten trials including 441 liver transplant recipients provided data for this review.There were no significant differences in the 90-day mortality (1 trial; 81 participants; 5/35 (adjusted proportion: 14.2%) in interferon group versus 5/46 (10.9%) in control group; RR 1.31; 95% CI 0.41 to 4.19); mortality at maximal follow-up (2 trials; 105 participants; 7/47 (adjusted proportion: 14.8%) in interferon group versus 10/58 (17.2%) in control group; RR 0.86; 95% CI 0.36 to 2.08); long-term mortality (1 trial; 81 participants; HR 0.45; 95% CI 0.13 to 1.56); mortality at maximal follow-up (1 trial; 54 participants; 1/26 (3.9%) in pegylated interferon group versus 2/28 (7.1%) in control group; RR 0.54; 95% CI 0.05 to 5.59); 90-day mortality (1 trial; 115 participants; 5/55 (9.1%) in pegylated interferon plus ribavirin group versus 3/60 (5.0%) in control group; RR 1.82; 95% 0.46 to 7.25); 90-day mortality (3 trials; 53 participants; 3/37 (adjusted proportion: 4.3%) in HCV antibody group versus 1/16 (6.3%) in placebo group; RR 0.69; 95% CI 0.15 to 3.11); or 90-day mortality (2 trials; 31 participants; 2/14 (adjusted proportion: 16.2%) in HCV antibody high-dose group versus 1/17 (5.9%) in HCV antibody low-dose group; RR 2.75; 95% CI; 0.30 to 25.35). There were no significant differences in the retransplantation at maximal follow-up (2 trials; 105 participants; 2/47 (adjusted proportion: 4.0%) in interferon group versus 2/58 (3.4%) in control group; RR 1.17; 95% CI 0.22 to 6.2); 90-day retransplantation (1 trial; 18 participants; 1/12 (8.3%) in HCV antibody group versus 0/6 (0%) in control group; RR 1.71; 95% CI 0.09 to 32.93); or 90-day retransplantation (1 trial; 12 participants; 1/6 (17.7%) in HCV antibody high-dose group versus 0/6 (0%) in HCV antibody low-dose group; RR 3.00; 95% CI 0.15 to 61.74). There were no significant differences in serious adverse events, graft rejection, worsening of fibrosis, or HCV recurrence between intervention and control groups in any of the comparisons that reported these outcomes. None of the trials reported quality of life, liver decompensation, intensive therapy unit stay, or hospital stay. Life-threatening adverse events were not reported in either group in any of the comparisons.

AUTHORS' CONCLUSIONS

There is currently no evidence to recommend prophylactic antiviral treatment to prevent recurrence of HCV infection either in primary liver transplantation or retransplantation. Further randomised clinical trials with adequate trial methodology and adequate duration of follow-up are necessary.

Additional glycosylation within a specific hypervariable region of subtype 3a of hepatitis C virus protects against virus neutralization

BACKGROUND

The envelope glycoprotein E2 of hepatitis C virus (HCV) contains several hypervariable regions. Interestingly, 2 regions of intragenotypic hypervariability within E2 have been described as being specific to HCV subtype 3a. Based on their amino acid position in E2, they were named HVR495 and HVR575. Here, we further investigated these regions in order to better understand their role in HCV infection.

METHODS

Sequences of HCV envelope glycoproteins from Pakistani patients infected with subtype 3a were cloned and compared with other subtype 3a sequences. The entry functions and the sensitivity to antibody neutralization of selected HCV glycoprotein sequences were tested in the HCV pseudotyped particles (HCVpp) system. In addition, the cell-cultured HCV system (HCVcc) was also used to confirm some of the data obtained with the HCVpp system.

RESULTS

We observed interesting new features within HVR495 and HVR575 for several subtype 3a isolates. Indeed, changes in glycosylation sites were observed with the appearance of a new glycosylation site within HVR495. Importantly, HCVpp and HCVcc that contained this new HVR495 glycosylation site were less sensitive to antibody neutralization.

CONCLUSIONS

We identified a new glycosylation site within the HVR495 region of HCV subtype 3a that has a protective effect against antibody neutralization.

Ultrastructural analysis of hepatitis C virus particles. Proc Natl Acad Sci U S A. 2013;110:9505-9510. [PMID: 23690609 DOI: 10.1073/pnas.1307527110]

Hepatitis C virus (HCV) is a major cause of chronic liver disease, with an estimated 170 million people infected worldwide. Low yields, poor stability, and inefficient binding to conventional EM grids have posed significant challenges to the purification and structural analysis of HCV. In this report, we generated an infectious HCV genome with an affinity tag fused to the E2 envelope glycoprotein. Using affinity grids, previously described to isolate proteins and macromolecular complexes for single-particle EM, we were able to purify enveloped particles directly from cell culture media. This approach allowed for rapid in situ purification of virions and increased particle density that were instrumental for cryo-EM and cryoelectron tomography (cryo-ET). Moreover, it enabled ultrastructural analysis of virions produced by primary human hepatocytes. HCV appears to be the most structurally irregular member of the Flaviviridae family. Particles are spherical, with spike-like projections, and heterogeneous in size ranging from 40 to 100 nm in diameter. Exosomes, although isolated from unfractionated culture media, were absent in highly infectious, purified virus preparations. Cryo-ET studies provided low-resolution 3D structural information of highly infectious virions. In addition to apolipoprotein (apo)E, HCV particles also incorporate apoB and apoA-I. In general, host apolipoproteins were more readily accessible to antibody labeling than HCV glycoproteins, suggesting either lower abundance or masking by host proteins.

Laser captured hepatocytes show association of butyrylcholinesterase gene loss and fibrosis progression in hepatitis C-infected drug users

Chronic hepatitis C virus (HCV) infection is complicated by hepatic fibrosis. Hypothesizing that early fibrogenic signals may originate in cells susceptible to HCV infection, hepatocyte gene expression was analyzed from persons with chronic HCV at different stages of liver fibrosis. Four HCV-infected subjects with precirrhosis liver fibrosis (Ishak fibrosis 3-5) were matched for age, race, and gender to five HCV-infected subjects with no evidence of fibrosis (Ishak fibrosis 0). Hepatocytes from each subject were isolated from liver biopsies using laser capture microdissection. Transcriptome profiling was performed on hepatocyte RNA using hybridization arrays. We found that hepatocytes in precirrhosis fibrosis were depleted for genes involved in small molecule and drug metabolism, especially butyrylcholinesterase (BCHE), a gene involved in the metabolism of drugs of abuse. Differential expression of BCHE was validated in the same tissues and cross-sectionally in an expanded cohort of 143 HCV-infected individuals. In a longitudinal study, serum BCHE activity was already decreased at study inception in 19 fibrosis progressors compared with 20 fibrosis nonprogressors (P < 0.05). Nonprogressors also had decreased BCHE activity over time compared with initial values, but these evolved a median (range) 8.6 (7.8-11.4) years after the study period inception (P < 0.05). Laser captured portal tracts were enriched for immune related genes when compared with hepatocytes but precirrhosis livers lost this enrichment.

CONCLUSION

Chronic HCV is associated with hepatocyte BCHE loss years before hepatic synthetic function is impaired. These results indicate that BCHE may be involved in the pathogenesis of HCV-related fibrosis among injection drug users.

Hepatitis C virus induces interferon-λ and interferon-stimulated genes in primary liver cultures

Hepatitis C virus (HCV) replication in primary liver cells is less robust than that in hepatoma cell lines, suggesting that innate antiviral mechanisms in primary cells may limit HCV replication or spread. Here we analyzed the expression of 47 genes associated with interferon (IFN) induction and signaling following HCV infection of primary human fetal liver cell (HFLC) cultures from 18 different donors. We report that cell culture-produced HCV (HCVcc) induced expression of Type III (λ) IFNs and of IFN-stimulated genes (ISGs). Little expression of Type I IFNs was detected. Levels of IFNλ and ISG induction varied among donors and, often, between adapted and nonadapted HCV chimeric constructs. Higher levels of viral replication were associated with greater induction of ISGs and of λ IFNs. Gene induction was dependent on HCV replication, as ultraviolet light-inactivated virus was not stimulatory and an antiviral drug, 2'-C-methyladenosine, reduced induction of λ IFNs and ISGs. The level of IFNλ protein induced was sufficient to inhibit HCVcc infection of naïve cultures.

CONCLUSION

Together, these results indicate that despite its reported abilities to blunt the induction of an IFN response, HCV infection is capable of inducing antiviral cytokines and pathways in primary liver cell cultures. Induction of ISGs and λ IFNs may limit the growth and spread of HCV in primary cell cultures and in the infected liver. HCV infection of HFLC may provide a useful model for the study of gene induction by HCV in vivo.

Toll-like receptor 2 senses hepatitis C virus core protein but not infectious viral particles

Toll-like receptors (TLRs) are pathogen recognition molecules activating the innate immune system. Cell surface expressed TLRs, such as TLR2 and TLR4, have been shown to play an important role in human host defenses against viruses through sensing of viral structural proteins. In this study, we aimed to elucidate whether TLR2 and TLR4 participate in inducing antiviral immunity against hepatitis C virus (HCV) by sensing viral structural proteins. We studied TLR2 and TLR4 activation by cell culture-derived infectious virions and serum-derived virions in comparison to purified recombinant HCV structural proteins and enveloped virus-like particles. Incubation of TLR2 or TLR4 transfected cell lines with recombinant core protein resulted in activation of TLR2-dependent signaling. In contrast, neither infectious virions nor enveloped HCV-like particles triggered TLR2 and TLR4 signaling. These findings suggest that monomeric HCV core protein but not intact infectious particles are sensed by TLR2. Impairment of interaction between TLR and the core in infectious viral particles may contribute to escape from innate antiviral immune responses.

Seroconversion to hepatitis C virus alternate reading frame protein during acute infection

The existence of hepatitis C virus (HCV) proteins encoded by alternate reading frames overlapping the core-encoding region has been suggested. Several mechanisms of production have been postulated, and the functions of these proteins in the HCV life cycle remain unknown. We analyzed cases of seroconversion to an alternate reading frame protein in a group of 17 patients infected by one of the two HCV genotype 1b strains during an outbreak in a hemodialysis unit. Three patients seroconverted, and antibodies were transiently detected in another patient. Three of these patients were infected by one of the two HCV strains, whereas the strain infecting the remaining patient could not be identified. Quasispecies sequence analysis of the core-coding region showed no differences in the core or +1 reading frame sequences that could explain alternate reading frame protein seroconversion in some but not all of the patients infected by one of the HCV strains, and no such difference was found between the two strains. Because differences in the structure of RNA elements could play a role in frameshift events, we conducted a predictive analysis of RNA folding. No difference was found between the patients who did and did not seroconvert to alternate reading frame protein.

CONCLUSION

Our findings prove that alternate reading frame proteins can be produced during acute HCV infection. However, seroconversion does not occur in all patients for unknown reasons. Alternate reading frame protein could be generated by minority quasispecies variants or variants that occur transiently.

Dissection of a viral autoprotease elucidates a function of a cellular chaperone in proteolysis

Replication of positive-strand RNA viruses involves translation of polyproteins which are proteolytically processed into functional peptides. These maturation steps often involve virus-encoded autoproteases specialized in generating their own N or C termini. Nonstructural protein 2 (NS2) of the pestivirus bovine viral diarrhea virus represents such an enzyme. Bovine viral diarrhea virus NS2 creates in cis its own C terminus and thereby releases an essential viral replication factor. As a unique feature, this enzyme requires for proteolytic activity stoichiometric amounts of a cellular chaperone termed Jiv (J-domain protein interacting with viral protein) or its fragment Jiv90. To obtain insight into the structural organization of the NS2 autoprotease, the basis for its restriction to cis cleavage, as well as its activation by Jiv, we dissected NS2 into functional domains. Interestingly, an N-terminal NS2 fragment covering the active center of the protease, cleaved in trans an artificial substrate composed of a C-terminal NS2 fragment and two downstream amino acids. In the authentic NS2, the 4 C-terminal amino acids interfered with binding and cleavage of substrates offered in trans. These findings strongly suggest an intramolecular product inhibition for the NS2 autoprotease. Remarkably, the chaperone fragment Jiv90 independently interacted with protease and substrate domain and turned out to be essential for the formation of a protease/substrate complex that is required for cleavage. Thus, the function of the cell-derived protease cofactor Jiv in proteolysis is regulation of protease/substrate interaction, which ultimately results in positioning of active site and substrate peptide into a cleavage-competent conformation.

Expression of hepatitis C virus core protein in hepatocytes does not modulate proliferation or apoptosis of CD8+ T cells

Hepatocytes are the primary targets of the hepatitis C virus (HCV). While immunosuppressive roles of HCV core protein have been found in several studies, it remains uncertain whether core protein expressed in hepatocytes rather than in immune cells affects the CD8+ T cell response. In order to transduce genes selectively into hepatocytes, we developed a baculoviral vector system that enabled primary hepatocytes to express a target epitope for CD8+ T cells, derived from ovalbumin (OVA), with or without HCV core protein. Culture of OVA-specific CD8+ T cells with hepatocytes infected with these baculoviral vectors revealed that core protein has no effect on proliferation or apoptosis of CD8+ T cells. Our results suggest that HCV core protein does not exert its suppressive role on the CD8+ T cell immune response through expression in hepatocytes.

The prevalence of hepatitis C virus infection in Korea: pooled analysis

This study evaluated the prevalence of hepatitis C virus (HCV) infections in Korea. Pooled estimates of the anti-HCV positivity were calculated using the data published in 15 reports on the general population and health check-up examinees. The overall pooled estimate of the prevalence of HCV among middle-aged adults (40 yr old and above) was 1.68% (95% confidence interval: 1.51-1.86%) during the year of 1990-2000 among the general population. Most of the published data indicated that the prevalence of anti-HCV increased with age. The anti-HCV positivity was significantly higher in females than in males. Because the risk of HCV exposure in blood recipients has decreased remarkably, the spread of HCV through means other than a transfusion must be prevented.