A review on hepatitis D: From virology to new therapies

Frequency of hepatitis D virus with different hepatitis B virus serological markers and coinfections in hospital patients from Argentina: synchronous testing of anti-HDV antibodies and HDV RNA

BACKGROUND

Hepatitis D virus (HDV) RNA-positive cases with total anti-HDV antibodies nonreactive were documented. Moreover, HDV infection was observed in subjects with occult hepatitis B virus infection. The prevalence of HDV infection in Argentina is low; however, further research in different populations is needed.

OBJECTIVE

This study aimed to perform synchronous HDV detection in reactive hepatitis B virus patients treated in a public hospital in the province of Buenos Aires, Argentina, some of whom were coinfected with hepatitis C virus and/or HIV. A total of 189 hepatitis B virus-reactive serum samples with or without hepatitis C virus and/or HIV coinfection were synchronously analyzed for anti-HDV antibodies and HDV RNA.

RESULTS

HDV prevalence was 4.2% with HDV RNA found in 61 samples, most of which were nonreactive to anti-HDV antibodies and hepatitis B surface antigen. Genotype 1 was identified in all HDV sequences. Moreover, triple and quadruple infections were observed, showing a high frequency of HDV infection in hospitalized patients not following the recommended diagnostic algorithm.

CONCLUSIONS

This study is evidence that the synchronous testing of anti-HDV antibodies and HDV RNA is necessary for the diagnosis of HDV infection in Argentina. Finally, further research is necessary to identify high-risk populations and improve prevention and control strategies for triple and quadruple infections and their potential consequences.

Targeting chronic liver diseases: Molecular markers, drug delivery strategies and future perspectives

Chronic liver inflammation, a pervasive global health issue, results in millions of annual deaths due to its progression from fibrosis to the more severe forms of cirrhosis and hepatocellular carcinoma (HCC). This insidious condition stems from diverse factors such as obesity, genetic conditions, alcohol abuse, viral infections, autoimmune diseases, and toxic accumulation, manifesting as chronic liver diseases (CLDs) such as metabolic dysfunction-associated steatotic liver disease (MASLD), metabolic dysfunction-associated steatohepatitis (MASH), alcoholic liver disease (ALD), viral hepatitis, drug-induced liver injury, and autoimmune hepatitis. Late detection of CLDs necessitates effective treatments to inhibit and potentially reverse disease progression. However, current therapies exhibit limitations in consistency and safety. A potential breakthrough lies in nanoparticle-based drug delivery strategies, offering targeted delivery to specific liver cell types, such as hepatocytes, Kupffer cells, and hepatic stellate cells. This review explores molecular targets for CLD treatment, ongoing clinical trials, recent advances in nanoparticle-based drug delivery, and the future outlook of this research field. Early intervention is crucial for chronic liver disease. Having a comprehensive understanding of current treatments, molecular biomarkers and novel nanoparticle-based drug delivery strategies can have enormous impact in guiding future strategies for the prevention and treatment of CLDs.

Hepatitis C Virus as a Possible Helper Virus in Human Hepatitis Delta Virus Infection

Previous studies reported that the hepatitis C virus (HCV) could help disseminate the hepatitis D virus (HDV) in vivo through hepatitis B virus (HBV)-unrelated ways, but with essentially inconclusive results. To try to shed light on this still-debated topic, 146 anti-HCV-positive subjects (of whom 91 HCV/HIV co-infected, and 43 with prior HCV eradication) were screened for anti-HDV antibodies (anti-HD), after careful selection for negativity to any serologic or virologic marker of current or past HBV infection. One single HCV/HIV co-infected patient (0.7%) tested highly positive for anti-HD, but with no positive HDV-RNA. Her husband, in turn, was a HCV/HIV co-infected subject with a previous contact with HBV. While conducting a thorough review of the relevant literature, the authors attempted to exhaustively describe the medical history of both the anti-HD-positive patient and her partner, believing it to be the key to dissecting the possible complex mechanisms of HDV transmission from one subject to another, and speculating that in the present case, it may have been HCV itself that behaved as an HDV helper virus. In conclusion, this preliminary research, while needing further validation in large prospective studies, provided some further evidence of a role of HCV in HDV dissemination in humans.

Major HBV splice variant encoding a novel protein important for infection

BACKGROUND & AIMS

HBV expresses more than 10 spliced RNAs from the viral pregenomic RNA, but their functions remain elusive and controversial. To address the function of HBV spliced RNAs, we generated splicing-deficient HBV mutants and conducted experiments to assess the impact of these mutants on HBV infection.

METHODS

HepG2-NTCP cells, human hepatocyte chimeric FRG mice (hu-FRG mice), and serum from patients with chronic hepatitis B were used for experiments on HBV infection. Additionally, SHifter assays and cryo-electron microscopy were performed.

RESULTS

We found the infectivity of splicing-deficient HBV was decreased 100-1,000-fold compared with that of wild-type HBV in hu-FRG mice. Another mutant, A487C, which loses the most abundant spliced RNA (SP1), also exhibits severely impaired infectivity. SP1 hypothetically encodes a novel protein HBcSP1 (HBc-Cys) that lacks the C-terminal cysteine from full-length HBc. In the SHifter assay, HBcSP1 was detected in wild-type viral particles at a ratio of about 20-100% vs. conventional HBc, as well as in the serum of patients with chronic hepatitis B, but not in A487C particles. When infection was conducted with a shorter incubation time of 4-8 h at lower PEG concentrations in HepG2-NTCP cells, the entry of the A487C mutant was significantly slower. SP1 cDNA complementation of the A487C mutant succeeded in rescuing its infectivity in hu-FRG mice and HepG2-NTCP cells. Moreover, cryo-electron microscopy revealed a disulfide bond between HBc cysteine 183 and 48 in the HBc intradimer of the A487C capsid, leading to a locked conformation that disfavored viral entry in contrast to the wild-type capsid.

CONCLUSIONS

Prior studies unveiled the potential integration of the HBc-Cys protein into the HBV capsid. We confirmed the proposal and validated its identity and function during infection.

IMPACT AND IMPLICATIONS

HBV SP1 RNA encodes a novel HBc protein (HBcSP1) that lacks the C-terminal cysteine from conventional HBc (HBc-Cys). HBcSP1 was detected in cell culture-derived HBV and confirmed in patients with chronic infection by both immunological and chemical modification assays at 10-50% of capsid. The splicing-deficient mutant HBV (A487C) impaired infectivity in human hepatocyte chimeric mice and viral entry in the HepG2-NTCP cell line. Furthermore, these deficiencies of the splicing-deficient mutant could be rescued by complementation with the SP1-encoded protein HBcSP1. We confirmed and validated the identity and function of HBcSP1 during infection, building on the current model of HBV particles.

Exosomes as Conduits: Facilitating Hepatitis B Virus-Independent Hepatitis D Virus Transmission and Propagation in Hepatocytes

A number of research studies, including ours, have spotlighted exosomes as critical facilitators of viral dissemination. While hepatitis B virus (HBV) transmission through exosomes has been studied, the focus on its satellite virus, the hepatitis delta virus (HDV), has been unexplored in this context. HDV, although being a defective virus, can replicate its genome autonomously within hepatocytes, independently of HBV. Investigations on Huh7 cells revealed an intriguing phenomenon: the HDV proteins, S-HDAg and L-HDAg, are transmitted between cells without a complete viral structure. Detailed analysis further revealed that the expression of these proteins not only bolstered exosome secretion but also ensured their enrichment within these vesicles. Our experimental approach utilized transfection of various plasmids to examine the role of HDV RNA and proteins in the process. One salient finding was the differential propagation of the HDV proteins S-HDAg and L-HDAg, suggesting intricate molecular mechanisms behind their transmission. Notably, the purity of our exosome preparations was monitored using markers such as TSG101 and CD81. Importantly, these exosomes were found to carry both HDV RNA and proteins, highlighting their role in HDV dissemination. This novel study underscores the role of exosomes in mediating the transmission of HDV components between hepatocytes independent of HBV. These revelations about the exosomal pathway of HDV transmission provide a foundation for the development of innovative therapeutic strategies against HDV infections.

Association of hepatitis delta virus with liver morbidity and mortality: A systematic literature review and meta-analysis

BACKGROUND AND AIMS

Studies have suggested that patients with chronic hepatitis B, either co- or superinfected, have more aggressive liver disease progression than those with the HDV. This systematic literature review and meta-analysis examined whether HDV RNA status is associated with increased risk of advanced liver disease events in patients who are HBsAg and HDV antibody positive.

APPROACH AND RESULTS

A total of 12 publications were included. Relative rates of progression to advanced liver disease event for HDV RNA+/detectable versus HDV RNA-/undetectable were extracted for analysis. Reported OR and HRs with 95% CI were pooled using the Hartung-Knapp-Sidik-Jonkman method for random-effects models. The presence of HDV RNA+ was associated with an increased risk of any advanced liver disease event [random effect (95% CI): risk ratio: 1.48 (0.93, 2.33); HR: 2.62 (1.55, 4.44)]. When compared to the patients with HDV RNA- status, HDV RNA+ was associated with a significantly higher risk of progressing to compensated cirrhosis [risk ratio: 1.74 (1.24, 2.45)] decompensated cirrhosis [HR: 3.82 (1.60, 9.10)], HCC [HR: 2.97 (1.87, 4.70)], liver transplantation [HR: 7.07 (1.61, 30.99)], and liver-related mortality [HR: 3.78 (2.18, 6.56)].

CONCLUSIONS

The patients with HDV RNA+ status have a significantly greater risk of liver disease progression than the patients who are HDV RNA-. These findings highlight the need for improved HDV screening and linkage to treatment to reduce the risk of liver-related morbidity and mortality.

Cell Culture Models for Hepatitis B and D Viruses Infection: Old Challenges, New Developments and Future Strategies

Chronic Hepatitis B and D Virus (HBV and HDV) co-infection is responsible for the most severe form of viral Hepatitis, the Hepatitis Delta. Despite an efficient vaccine against HBV, the HBV/HDV infection remains a global health burden. Notably, no efficient curative treatment exists against any of these viruses. While physiologically distinct, HBV and HDV life cycles are closely linked. HDV is a deficient virus that relies on HBV to fulfil is viral cycle. As a result, the cellular response to HDV also influences HBV replication. In vitro studying of HBV and HDV infection and co-infection rely on various cell culture models that differ greatly in terms of biological relevance and amenability to classical virology experiments. Here, we review the various cell culture models available to scientists to decipher HBV and HDV virology and host-pathogen interactions. We discuss their relevance and how they may help address the remaining questions, with one objective in mind: the development of new therapeutic approaches allowing viral clearance in patients.

JAK1 promotes HDV replication and is a potential target for antiviral therapy

BACKGROUND & AIMS

Chronic co-infection with HBV and HDV leads to the most aggressive form of chronic viral hepatitis. To date, no treatment induces efficient viral clearance, and a better characterization of virus-host interactions is required to develop new therapeutic strategies.

METHODS

Using loss-of-function strategies, we validated the unexpected proviral activity of Janus kinase 1 (JAK1) - a key player in innate immunity - in the HDV life cycle and determined its mechanism of action on HDV through various functional analyses including co-immunoprecipitation assays.

RESULTS

We confirmed the key role of JAK1 kinase activity in HDV infection. Moreover, our results suggest that JAK1 inhibition is associated with a modulation of ERK1/2 activation and S-HDAg phosphorylation, which is crucial for viral replication. Finally, we showed that FDA-approved JAK1-specific inhibitors are efficient antivirals in relevant in vitro models including primary human hepatocytes.

CONCLUSIONS

Taken together, we uncovered JAK1 as a key host factor for HDV replication and a potential target for new antiviral treatment.

IMPACT AND IMPLICATIONS

Chronic hepatitis D is the most aggressive form of chronic viral hepatitis. As no curative treatment is currently available, new therapeutic strategies based on host-targeting agents are urgently needed. Here, using loss-of-function strategies, we uncover an unexpected interaction between JAK1, a major player in the innate antiviral response, and HDV infection. We demonstrated that JAK1 kinase activity is crucial for both the phosphorylation of the delta antigen and the replication of the virus. By demonstrating the antiviral potential of several FDA-approved JAK1 inhibitors, our results could pave the way for the development of innovative therapeutic strategies to tackle this global health threat.

Dynamics of Virological and Clinical Response Parameters of Bulevirtide Treatment for Hepatitis D: Real-World Data

Background and Aims

The entry inhibitor bulevirtide represents the first specific treatment for hepatitis-D virus (HDV)-infected patients. In clinical trials, around 80% of patients achieve normalization of alanine aminotransferase (ALT) with about 60% virological response after 1 year, but little is known about the dynamics of responses and clinical predictors of treatment outcomes. We report our single-center data from 15 patients and describe response dynamics, clinical outcomes, and predictive factors for treatment response.

Methods

Retrospective data from 15 patients have been analyzed at our department who started treatment with bulevirtide between 10/2020 and 08/2022. According to our standard procedures, laboratory parameters were controlled monthly; transient elastography was performed every 3 months, and the treatment duration was 12 months.

Results

Treatment response rates after 1 year of treatment were similar to published data from clinical trials. ALT normalization usually occurs between months 2-6 of treatment, followed by a virological response after ≥6 months. Patients with more severe hepatitis at the start of treatment were less likely to respond in the first year of treatment. Loss of HDV-RNA was observed in one-third of patients after ≥1 year of treatment. Low body mass index and high alpha-fetoprotein at baseline were possible predictors of a delayed treatment response.

Conclusion

Bulevirtide is a safe treatment option for HDV, leading to a fast hepatological response. Of note, decrease in transaminases precedes virological response. Patients with high viral load and ALT levels respond slower, but nonresponders (as classified by Food and Drug Administration criteria) still show a reduction in viremia. Longer observation periods are required to determine the optimal duration of bulevirtide monotherapy.

Hepatitis B Surface Antigen Isoforms: Their Clinical Implications, Utilisation in Diagnosis, Prevention and New Antiviral Strategies

The hepatitis B surface antigen (HBsAg) is a multifunctional glycoprotein composed of large (LHB), middle (MHB), and small (SHB) subunits. HBsAg isoforms have numerous biological functions during HBV infection-from initial and specific viral attachment to the hepatocytes to initiating chronic infection with their immunomodulatory properties. The genetic variability of HBsAg isoforms may play a role in several HBV-related liver phases and clinical manifestations, from occult hepatitis and viral reactivation upon immunosuppression to fulminant hepatitis and hepatocellular carcinoma (HCC). Their immunogenic properties make them a major target for developing HBV vaccines, and in recent years they have been recognised as valuable targets for new therapeutic approaches. Initial research has already shown promising results in utilising HBsAg isoforms instead of quantitative HBsAg for correctly evaluating chronic infection phases and predicting functional cures. The ratio between surface components was shown to indicate specific outcomes of HBV and HDV infections. Thus, besides traditional HBsAg detection and quantitation, HBsAg isoform quantitation can become a useful non-invasive biomarker for assessing chronically infected patients. This review summarises the current knowledge of HBsAg isoforms, their potential usefulness and aspects deserving further research.

Hepatitis D infection induces IFN-β-mediated NK cell activation and TRAIL-dependent cytotoxicity

Background and aims

The co-infection of hepatitis B (HBV) patients with the hepatitis D virus (HDV) causes the most severe form of viral hepatitis and thus drastically worsens the course of the disease. Therapy options for HBV/HDV patients are still limited. Here, we investigated the potential of natural killer (NK) cells that are crucial drivers of the innate immune response against viruses to target HDV-infected hepatocytes.

Methods

We established in vitro co-culture models using HDV-infected hepatoma cell lines and human peripheral blood NK cells. We determined NK cell activation by flow cytometry, transcriptome analysis, bead-based cytokine immunoassays, and NK cell-mediated effects on T cells by flow cytometry. We validated the mechanisms using CRISPR/Cas9-mediated gene deletions. Moreover, we assessed the frequencies and phenotype of NK cells in peripheral blood of HBV and HDV superinfected patients.

Results

Upon co-culture with HDV-infected hepatic cell lines, NK cells upregulated activation markers, interferon-stimulated genes (ISGs) including the death receptor ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), produced interferon (IFN)-γ and eliminated HDV-infected cells via the TRAIL-TRAIL-R2 axis. We identified IFN-β released by HDV-infected cells as an important enhancer of NK cell activity. In line with our in vitro data, we observed activation of peripheral blood NK cells from HBV/HDV co-infected, but not HBV mono-infected patients.

Conclusion

Our data demonstrate NK cell activation in HDV infection and their potential to eliminate HDV-infected hepatoma cells via the TRAIL/TRAIL-R2 axis which implies a high relevance of NK cells for the design of novel anti-viral therapies.

CRISPR/Cas13a-Assisted accurate and portable hepatitis D virus RNA detection

BACKGROUND & AIMS

Hepatitis delta virus (HDV) infection accelerates the progression of chronic hepatitis B virus (HBV) infection, posing a large economic and health burden to patients. At present, there remains a lack of accurate and portable detection methods for HDV RNA. Here, we aim to establish a convenient, rapid, highly sensitive and specific method to detect HDV RNA using CRISPR-Cas13a technology.

METHODS

We established fluorescence (F) and lateral flow strip (L) assays based on CRISPR-Cas13a combined with RT-PCR and RT-RAA for HDV RNA detection, respectively. we conducted a cohort study of 144 patients with HDV-IgG positive to evaluate the CRISPR-Cas13a diagnostic performance for identifying HDV in clinical samples, compared to RT-qPCR and RT-ddPCR.

RESULTS

For synthetic HDV RNA plasmids, the sensitivity of RT-PCR-CRISPR-based fluorescence assays was 1 copy/μL, higher than that of RT-qPCR (10 copies/μL) and RT-ddPCR (10 copies/μL); for HDV RNA-positive samples, the sensitivity of RT-RAA-CRISPR-based fluorescence and lateral flow strip assays was 10 copies/μL, as low as that of RT-qPCR and RT-ddPCR, and the assay took only approximately 85 min. Additionally, the positivity rates of anti-HDV IgG-positive samples detected by the RT-qPCR, RT-ddPCR, RT-PCR-CRISPR fluorescence and RT-RAA-CRISPR lateral flow strip methods were 66.7% (96/144), 76.4% (110/144), 81.9% (118/144), and 72.2% (104/144), respectively.

CONCLUSIONS

We developed a highly sensitive and specific, as well as a portable and easy CRISPR-based assay for the detection of HDV RNA, which could be a prospective measure for monitoring the development of HDV infection and evaluating the therapeutic effect.

Comparative effectiveness of seven interventions for chronic hepatitis D: a systematic review and network meta-analysis of randomized controlled trials

OBJECTIVE

To compare the effectiveness of seven major interventions [Bulevirtide (BLV), Interferon (IFN), Nucleoside analogs (NAs), BLV + IFN, BLV + NAs, IFN + NAs, and Placebo] to treat chronic hepatitis D.

METHODS

We followed PRISMA-NMA guidelines, searched databases (Cochrane Library, PubMed, EMBASE, and Web Of Science) for eligible randomized controlled trials (RCTs), and applied STATA17.0 software to execute the meta-analysis.

RESULTS

We included 14 randomized controlled trials (814 patients) comparing seven different interventions. The results of the network meta-analysis showed that: ① Sustained virological response (after 24 weeks of follow-up): Four intervention groups (BLV + IFN, IFN alone, IFN + NAs, and NAs alone) were effective (relative risk (RR) = 13.30, 95% confidence interval (Cl) [1.68,105.32], RR = 12.13, 95% Cl [1.46,101.04], RR = 5.05, 95% Cl [1.68,15.19], RR = 5.03, 95% Cl [1.66,15.20]), with no statistically significant differences between the four groups. The top three in probability rankings were: BLV + NAs, BLV + IFN, and BLV alone (surface under the cumulative ranking curve (SUCRA) = 86.8%, 80.3%, and 48.4%; ② Sustained biochemical response (after 24 weeks of follow-up): BLV + IFN and IFN were superior to BLV (RR = 14.71, 95% Cl [1.14,189.07], RR = 16.67, 95% Cl [1.39,199.52]). The top three were BLV alone, BLV + NAs, and BLV + IFN (SUCRA = 86.9%,81.2%, and 64.3%). ③ Histological response: NAs were superior to BLV (RR = 2.08, 95% Cl [1.10,3.93]), whereas the difference between other treatment regimens was not statistically significant, and the top three in the probability ranking were BLV alone, BLV + NAs, and BLV + IFN (SUCRA = 75.6%, 75.6%, and 61.8%).

CONCLUSIONS

IFN, IFN + BLV, and IFN + NAs were effective in clearing HDV RNA and normalizing alanine aminotransferase levels; however, IFN and IFN + NAs had a high rate of viral relapse at 24 weeks post-treatment follow-up. There was no additional benefit of adding NAs to IFN therapy for chronic hepatitis D; however, the combination of IFN + BLV significantly improved short-term HDV RNA clearance, which showed strong synergistic effects. The seven regimens included in the study did not contribute significantly to liver histological improvement. Therefore, the IFN + BLV combination has the most potential as a treatment option to improve the long-term prognosis or even cure chronic hepatitis D.

TRIAL REGISTRATION

This systematic evaluation and meta-analysis was registered with PROSPERO under the registration number: CRD42022314544.).

Hepatitis D virus dual-infection among Chinese hepatitis B patient related to hepatitis B surface antigen, hepatitis B virus DNA and age

BACKGROUND

The screening practices for hepatitis D virus (HDV) are diverse and non-standardized worldwide, and the exact prevalence of HDV is uncertain.

AIM

To estimate HDV prevalence and investigate viral marker quantity trends in patients with hepatitis D.

METHODS

We collected 5594 serum samples from patients with hepatitis B in Jilin Province, China (3293 males and 2301 females, age range of 2 to 89 years). We then conducted tests for hepatitis B surface antigen (HBsAg), hepatitis B Virus (HBV) DNA, anti-hepatitis D antigen (HDAg), and HDV RNA.

RESULTS

We found that the prevalence of anti-HDAg and HDV RNA among hepatitis B patient were 3.6% (3.2-4.2%) and 1.2% (0.9-1.5%), respectively, 87.69% of hepatitis D patients were 51-70 years old. HDV infection screening positive rate of patients with HBV DNA levels below 2000 IU/mL (2.0%) was higher than those above 2000 IU/mL (0.2%). Among anti-HDAg positive patients, the HDV RNA positive rate was positively correlated with the HBsAg level and anti-HDAg level. There was a weak correlation between HBsAg and anti-HDAg levels among hepatitis D patients.

CONCLUSION

Our study highlights the importance of considering multiple factors when assessing the severity of HDV infection, comprehensive evaluation of patients' clinical and laboratory parameters is necessary for proper diagnosis and treatment.

Interferon-Free Regimens and Direct-Acting Antiviral Agents for Delta Hepatitis: Are We There Yet?

Chronic delta hepatitis is a global health problem. Although a smaller percentage of chronic HBV-infected patients are coinfected with the hepatitis delta virus, these patients have a higher risk of an accelerated progression to fulminant "delta hepatitis", cirrhosis, hepatic decompensation, and hepatocellular carcinoma, putting a financial strain on the healthcare system and increasing the need for a liver transplant. Since its discovery, tremendous efforts have been directed toward understanding the intricate pathogenic mechanisms, discovering the complex viral replication process, the essential replicative intermediates, and cell division-mediated viral spread, which enables virion viability. The consideration of the interaction between HBV and HDV is crucial in the process of developing novel pharmaceuticals. Until just recently, interferon-based therapy was the only treatment available worldwide. This review aims to present the recent advancements in understanding the life cycle of HDV, which have consequently facilitated the development of innovative drug classes. Additionally, we will examine the antiviral strategies currently in phases II and III of development, including bulevirtide (an entry inhibitor), lonafarnib (a prenylation inhibitor), and REP 2139 (an HBsAg release inhibitor).

Hepatitis delta virus RNA decline post-inoculation in human NTCP transgenic mice is biphasic

Chronic infection with hepatitis B and delta viruses (HDV) is the most serious form of viral hepatitis due to more severe manifestations of an accelerated progression to liver fibrosis, cirrhosis, and hepatocellular carcinoma. We characterized early HDV kinetics post-inoculation and incorporated mathematical modeling to provide insights into host-HDV dynamics. We analyzed HDV RNA serum viremia in 192 immunocompetent (C57BL/6) and immunodeficient (NRG) mice that did or did not transgenically express the HDV receptor-human sodium taurocholate co-transporting polypeptide (hNTCP). Kinetic analysis indicates an unanticipated biphasic decline consisting of a sharp first-phase and slower second-phase decline regardless of immunocompetence. HDV decline after re-inoculation again followed a biphasic decline; however, a steeper second-phase HDV decline was observed in NRG-hNTCP mice compared to NRG mice. HDV-entry inhibitor bulevirtide administration and HDV re-inoculation indicated that viral entry and receptor saturation are not major contributors to clearance, respectively. The biphasic kinetics can be mathematically modeled by assuming the existence of a non-specific-binding compartment with a constant on/off-rate and the steeper second-phase decline by a loss of bound virus that cannot be returned as free virus to circulation. The model predicts that free HDV is cleared with a half-life of 35 minutes (standard error, SE: 6.3), binds to non-specific cells with a rate of 0.05 per hour (SE: 0.01), and returns as free virus with a rate of 0.11 per hour (SE: 0.02). Characterizing early HDV-host kinetics elucidates how quickly HDV is either cleared or bound depending on the immunological background and hNTCP presence. IMPORTANCE The persistence phase of HDV infection has been studied in some animal models; however, the early kinetics of HDV in vivo is incompletely understood. In this study, we characterize an unexpectedly HDV biphasic decline post-inoculation in immunocompetent and immunodeficient mouse models and use mathematical modeling to provide insights into HDV-host dynamics.

Gastrointestinal tract and viral pathogens

Viral gastroenteritis is the most common viral illness that affects the gastrointestinal (GI) tract, causing inflammation and irritation of the lining of the stomach and intestines. Common signs and symptoms associated with this condition include abdominal pain, diarrhea, and dehydration. The infections commonly involved in viral gastroenteritis are rotavirus, norovirus, and adenovirus, which spread through the fecal-oral and contact routes and cause non-bloody diarrhea. These infections can affect both immunocompetent and immunocompromised individuals. Since the pandemic in 2019, coronavirus gastroenteritis has increased in incidence and prevalence. Morbidity and mortality rates from viral gastroenteritis have declined significantly over the years due to early recognition, treatment with oral rehydration salts, and prompt vaccination. Improved sanitation measures have also played a key role in reducing the transmission of infection. In addition to viral hepatitis causing liver disease, herpes virus, and cytomegalovirus are responsible for ulcerative GI disease. They are associated with bloody diarrhea and commonly occur in im-munocompromised individuals. Hepatitis viruses, Epstein-Barr virus, herpesvirus 8, and human papillomavirus have been involved in benign and malignant diseases. This mini review aims to list different viruses affecting the GI tract. It will cover common symptoms aiding in diagnosis and various important aspects of each viral infection that can aid diagnosis and management. This will help primary care physicians and hospitalists diagnose and treat patients more easily.

Epidemiology Pattern, Prevalent Genotype Distribution, Fighting Stigma and Control Options for Hepatitis D in Bulgaria and Other European Countries

Hepatitis D virus (HDV) is a satellite virus that causes the most aggressive form of all viral hepatitis in individuals already infected with HBV (hepatitis B virus). In recent years, there has been a negative trend towards an increase in the prevalence of chronic hepatitis D in Europe, especially among immigrant populations coming from regions endemic for the virus. The aim of this review is to analyse the current epidemiology of chronic HDV, routes of transmission, prevalent genotype, its management, prevention, fighting stigma and options for viral control in European countries, such as Bulgaria.

Hepatitis Delta Virus Antigens Trigger Oxidative Stress, Activate Antioxidant Nrf2/ARE Pathway, and Induce Unfolded Protein Response

Hepatitis delta virus (HDV) is a viroid-like satellite that may co-infect individuals together with hepatitis B virus (HBV), as well as cause superinfection by infecting patients with chronic hepatitis B (CHB). Being a defective virus, HDV requires HBV structural proteins for virion production. Although the virus encodes just two forms of its single antigen, it enhances the progression of liver disease to cirrhosis in CHB patients and increases the incidence of hepatocellular carcinoma. HDV pathogenesis so far has been attributed to virus-induced humoral and cellular immune responses, while other factors have been neglected. Here, we evaluated the impact of the virus on the redox status of hepatocytes, as oxidative stress is believed to contribute to the pathogenesis of various viruses, including HBV and hepatitis C virus (HCV). We show that the overexpression of large HDV antigen (L-HDAg) or autonomous replication of the viral genome in cells leads to increased production of reactive oxygen species (ROS). It also leads to the upregulated expression of NADPH oxidases 1 and 4, cytochrome P450 2E1, and ER oxidoreductin 1α, which have previously been shown to mediate oxidative stress induced by HCV. Both HDV antigens also activated the Nrf2/ARE pathway, which controls the expression of a spectrum of antioxidant enzymes. Finally, HDV and its large antigen also induced endoplasmic reticulum (ER) stress and the concomitant unfolded protein response (UPR). In conclusion, HDV may enhance oxidative and ER stress induced by HBV, thus aggravating HBV-associated pathologies, including inflammation, liver fibrosis, and the development of cirrhosis and hepatocellular carcinoma.

Hepatitis delta virus RNA decline post inoculation in human NTCP transgenic mice is biphasic

Background and Aims

Chronic infection with hepatitis B and hepatitis delta viruses (HDV) is considered the most serious form of viral hepatitis due to more severe manifestations of and accelerated progression to liver fibrosis, cirrhosis, and hepatocellular carcinoma. There is no FDA-approved treatment for HDV and current interferon-alpha treatment is suboptimal. We characterized early HDV kinetics post inoculation and incorporated mathematical modeling to provide insights into host-HDV dynamics.

Methods

We analyzed HDV RNA serum viremia in 192 immunocompetent (C57BL/6) and immunodeficient (NRG) mice that did or did not transgenically express the HDV receptor - human sodium taurocholate co-transporting peptide (hNTCP).

Results

Kinetic analysis indicates an unanticipated biphasic decline consisting of a sharp first-phase and slower second-phase decline regardless of immunocompetence. HDV decline after re-inoculation again followed a biphasic decline; however, a steeper second-phase HDV decline was observed in NRG-hNTCP mice compared to NRG mice. HDV-entry inhibitor bulevirtide administration and HDV re-inoculation indicated that viral entry and receptor saturation are not major contributors to clearance, respectively. The biphasic kinetics can be mathematically modeled by assuming the existence of a non-specific binding compartment with a constant on/off-rate and the steeper second-phase decline by a loss of bound virus that cannot be returned as free virus to circulation. The model predicts that free HDV is cleared with a half-life of 18 minutes (standard error, SE: 2.4), binds to non-specific cells with a rate of 0.06 hour -1 (SE: 0.03), and returns as free virus with a rate of 0.23 hour -1 (SE: 0.03).

Conclusions

Understanding early HDV-host kinetics will inform pre-clinical therapeutic kinetic studies on how the efficacy of anti-HDV therapeutics can be affected by early kinetics of viral decline.

LAY SUMMARY

The persistence phase of HDV infection has been studied in some animal models, however, the early kinetics of HDV in vivo is incompletely understood. In this study, we characterize an unexpectedly HDV biphasic decline post inoculation in immunocompetent and immunodeficient mouse models and use mathematical modeling to provide insights into HDV-host dynamics. Understanding the kinetics of viral clearance in the blood can aid pre-clinical development and testing models for anti-HDV therapeutics.

Identification of selective hepatitis delta virus ribozyme inhibitors by high-throughput screening of small molecule libraries

Background & Aims

Chronic hepatitis delta is the most severe form of chronic viral hepatitis and is associated with faster progression towards cirrhosis, liver decompensation, and hepatocellular carcinoma. Hepatitis delta virus (HDV)'s tight dependency on hepatitis B virus and the host cell machinery for its life cycle limits the development of direct-acting antivirals. Thus, we aimed to identify compounds that could block HDV replication by targeting its antigenomic ribozyme.

Methods

We generated stable Huh7 human hepatoma cells expressing a reporter gene (Gaussia luciferase) either downstream (Gluc-2xRz) or upstream (2xRz-Gluc) of two HDV antigenomic ribozyme sequences. We performed high-throughput screening of three small molecule libraries. The secreted luciferase was measured as a readout of ribozyme inhibition upon addition of the molecules. Each plate was considered valid when the Z factor was >0.4. Specificity and toxicity evaluations were performed for the hits with a Z-score >5 and half-maximal inhibitory concentration was calculated by performing a dose-response experiment.

Results

A dose-dependent induction of luciferase expression was detected in Gluc-2xRz-transfected cells incubated with the antisense morpholino, suggesting that the catalytic activity of the ribozyme cloned downstream of the reporter gene was efficiently inhibited. Among the 6,644 compounds screened, we identified four compounds that showed a specific inhibitory effect on the HDV antigenomic ribozyme in Gluc-2xRz cells, i.e. three histone deacetylase inhibitors and the purine analogue 8-azaguanine. The latter also significantly decreased HDV replication (by 40%) in differentiated HepaRG cells six days post infection.

Conclusion

Using a novel cell culture model, we identified four small molecules active against the antigenomic HDV ribozyme. These results may provide insights into the structural requirements of molecules designed for the potent and specific inhibition of HDV replication.

Impact and implications

Chronic hepatitis delta is the most severe form of chronic viral hepatitis and is associated with faster progression towards cirrhosis, liver decompensation, and the development of hepatocellular carcinoma. Despite the current development of several new compounds, there is still a need for efficient antiviral treatments specifically targeting hepatitis delta virus (HDV). This work describes a novel cell culture model that allows for the high-throughput screening of compounds able to inhibit HDV ribozymes. We identified four small molecules active against the antigenomic HDV ribozyme (the ribozyme involved in the early step of HDV replication), with the strongest activity shown by 8-azaguanine, a purine analogue. Our data may provide insights into the structural requirements of molecules designed to inhibit HDV.

Hepatitis B and Hepatitis D Viruses: A Comprehensive Update with an Immunological Focus

Hepatitis B virus (HBV) and hepatitis delta virus (HDV) are highly prevalent viruses estimated to infect approximately 300 million people and 12-72 million people worldwide, respectively. HDV requires the HBV envelope to establish a successful infection. Concurrent infection with HBV and HDV can result in more severe disease outcomes than infection with HBV alone. These viruses can cause significant hepatic disease, including cirrhosis, fulminant hepatitis, and hepatocellular carcinoma, and represent a significant cause of global mortality. Therefore, a thorough understanding of these viruses and the immune response they generate is essential to enhance disease management. This review includes an overview of the HBV and HDV viruses, including life cycle, structure, natural course of infection, and histopathology. A discussion of the interplay between HDV RNA and HBV DNA during chronic infection is also included. It then discusses characteristics of the immune response with a focus on reactions to the antigenic hepatitis B surface antigen, including small, middle, and large surface antigens. This paper also reviews characteristics of the immune response to the hepatitis D antigen (including small and large antigens), the only protein expressed by hepatitis D. Lastly, we conclude with a discussion of recent therapeutic advances pertaining to these viruses.

Underestimated Prevalence of HIV, Hepatitis B Virus (HBV), and Hepatitis D Virus (HDV) Triple Infection Globally: Systematic Review and Meta-analysis

BACKGROUND

Hepatitis delta virus (HDV) is a satellite RNA virus that relies on hepatitis B virus (HBV) for transmission. HIV/HBV/HDV coinfection or triple infection is common and has a worse prognosis than monoinfection.

OBJECTIVE

We aimed to reveal the epidemiological characteristics of HIV/HBV/HDV triple infection in the global population.

METHODS

A systematic literature search in PubMed, Embase, and the Cochrane Library was performed for studies of the prevalence of HIV/HBV/HDV triple infection published from January 1, 1990, to May 31, 2021. The Der Simonian-Laird random effects model was used to calculate the pooled prevalence.

RESULTS

We included 14 studies with 11,852 participants. The pooled triple infection rate in the global population was 7.4% (877/11,852; 95% CI 0.73%-29.59%). The results of the subgroup analysis showed that the prevalence of triple infection was significantly higher in the Asian population (214/986, 21.4%; 95% CI 7.1%-35.8%), in men (212/5579, 3.8%; 95% CI 2.5%-5.2%), and in men who have sex with men (216/2734, 7.9%; 95% CI 4.3%-11.4%). In addition, compared with people living with HIV, the HIV/HBV/HDV triple infection rate was higher in people with hepatitis B.

CONCLUSIONS

This meta-analysis suggests that the prevalence of HIV/HBV/HDV triple infection in the global population is underestimated, and we should focus more effort on the prevention and control of HIV/HBV/HDV triple infection.

TRIAL REGISTRATION

PROSPERO CRD42021273949; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=273949.

Viral hepatitis: A narrative review of hepatitis A–E

Viral hepatitis continues to be a major health concern leading to hepatic decompensation ranging from acute hepatitis to cirrhosis and hepatocellular carcinoma. The hepatic and extrahepatic manifestations are not only debilitating but also associated with a significant economic burden. Over the last two decades, the field of virology has made significant breakthroughs leading to a better understanding of the pathophysiology of viral hepatitis, which in turn has led to new therapeutic options. The advent of direct-acting antiviral agents changed the landscape of hepatitis C virus (HCV) therapy, and new drugs are in the pipeline for chronic hepatitis B virus (HBV) treatment. There has also been a significant emphasis on screening and surveillance programs, widespread availability of vaccines, and linkage of care. Despite these efforts, significant gaps persist in care, and there is a pressing need for increased collaboration and teamwork across the globe to achieve a reduction of disease burden and elimination of HBV and HCV.

Viral hepatitis and hepatocellular carcinoma: From molecular pathways to the role of clinical surveillance and antiviral treatment

Hepatocellular carcinoma (HCC) is a global health challenge. Due to the high prevalence in low-income countries, hepatitis B virus (HBV) and hepatitis C virus infections remain the main risk factors for HCC occurrence, despite the increasing frequencies of non-viral etiologies. In addition, hepatitis D virus coinfection increases the oncogenic risk in patients with HBV infection. The molecular processes underlying HCC development are complex and various, either independent from liver disease etiology or etiology-related. The reciprocal interlinkage among non-viral and viral risk factors, the damaged cellular microenvironment, the dysregulation of the immune system and the alteration of gut-liver-axis are known to participate in liver cancer induction and progression. Oncogenic mechanisms and pathways change throughout the natural history of viral hepatitis with the worsening of liver fibrosis. The high risk of cancer incidence in chronic viral hepatitis infected patients compared to other liver disease etiologies makes it necessary to implement a proper surveillance, both through clinical-biochemical scores and periodic ultrasound assessment. This review aims to outline viral and microenvironmental factors contributing to HCC occurrence in patients with chronic viral hepatitis and to point out the importance of surveillance programs recommended by international guidelines to promote early diagnosis of HCC.

Viral hepatitis: A global burden needs future directions for the management

Viral hepatitis is an acute or chronic liver disease due to the infection from Hepatitis A, B, C, D and E viruses. It can cause severe liver damage such as cirrhosis, liver failure and liver cancer. To avoid such fatal complications, hepatitis patients must be diagnosed, pathologized and treated as soon as possible. Furthermore, these hepatitis viruses infect through different routes, resulting in distinct disease pathologies, severity and even the need for specific treatment strategies to combat the infection.

Signaling Induced by Chronic Viral Hepatitis: Dependence and Consequences

Chronic viral hepatitis is a main cause of liver disease and hepatocellular carcinoma. There are striking similarities in the pathological impact of hepatitis B, C, and D, although these diseases are caused by very different viruses. Paired with the conventional study of protein-host interactions, the rapid technological development of -omics and bioinformatics has allowed highlighting the important role of signaling networks in viral pathogenesis. In this review, we provide an integrated look on the three major viruses associated with chronic viral hepatitis in patients, summarizing similarities and differences in virus-induced cellular signaling relevant to the viral life cycles and liver disease progression.

The Interplay between Autophagy and Virus Pathogenesis-The Significance of Autophagy in Viral Hepatitis and Viral Hemorrhagic Fevers

Autophagy is a process focused on maintaining the homeostasis of organisms; nevertheless, the role of this process has also been widely documented in viral infections. Thus, xenophagy is a selective form of autophagy targeting viruses. However, the relation between autophagy and viruses is ambiguous-this process may be used as a strategy to fight with a virus, but is also in favor of the virus's replication. In this paper, we have gathered data on autophagy in viral hepatitis and viral hemorrhagic fevers and the relations impacting its viral pathogenesis. Thus, autophagy is a potential therapeutic target, but research is needed to fully understand the mechanisms by which the virus interacts with the autophagic machinery. These studies must be performed in specific research models other than the natural host for many reasons. In this paper, we also indicate Lagovirus europaeus virus as a potentially good research model for acute liver failure and viral hemorrhagic disease.

Hepatitis B virus integrations promote local and distant oncogenic driver alterations in hepatocellular carcinoma

OBJECTIVE

Infection by HBV is the main risk factor for hepatocellular carcinoma (HCC) worldwide. HBV directly drives carcinogenesis through integrations in the human genome. This study aimed to precisely characterise HBV integrations, in relation with viral and host genomics and clinical features.

DESIGN

A novel pipeline was set up to perform viral capture on tumours and non-tumour liver tissues from a French cohort of 177 patients mainly of European and African origins. Clonality of each integration event was determined with the localisation, orientation and content of the integrated sequence. In three selected tumours, complex integrations were reconstructed using long-read sequencing or Bionano whole genome mapping.

RESULTS

Replicating HBV DNA was more frequently detected in non-tumour tissues and associated with a higher number of non-clonal integrations. In HCC, clonal selection of HBV integrations was related to two different mechanisms involved in carcinogenesis. First, integration of viral enhancer nearby a cancer-driver gene may lead to a strong overexpression of oncogenes. Second, we identified frequent chromosome rearrangements at HBV integration sites leading to cancer-driver genes (TERT, TP53, MYC) alterations at distance. Moreover, HBV integrations have direct clinical implications as HCC with a high number of insertions develop in young patients and have a poor prognosis.

CONCLUSION

Deep characterisation of HBV integrations in liver tissues highlights new HBV-associated driver mechanisms involved in hepatocarcinogenesis. HBV integrations have multiple direct oncogenic consequences that remain an important challenge for the follow-up of HBV-infected patients.

Hepatitis D: advances and challenges

Hepatitis D virus (HDV) infection causes the most severe form of viral hepatitis with rapid progression to cirrhosis, hepatic decompensation, and hepatocellular carcinoma. Although discovered > 40 years ago, little attention has been paid to this pathogen from both scientific and public communities. However, effectively combating hepatitis D requires advanced scientific knowledge and joint efforts from multi-stakeholders. In this review, we emphasized the recent advances in HDV virology, epidemiology, clinical feature, treatment, and prevention. We not only highlighted the remaining challenges but also the opportunities that can move the field forward.

Inspecting the Ribozyme Region of Hepatitis Delta Virus Genotype 1: Conservation and Variability

The hepatitis delta virus (HDV) genome has an autocatalytic region called the ribozyme, which is essential for viral replication. The aim of this study was to use next-generation sequencing (NGS) to analyze the ribozyme quasispecies (QS) in order to study its evolution and identify highly conserved regions potentially suitable for a gene-silencing strategy. HDV RNA was extracted from 2 longitudinal samples of chronic HDV patients and the ribozyme (nucleotide, nt 688-771) was analyzed using NGS. QS conservation, variability and genetic distance were analyzed. Mutations were identified by aligning sequences with their specific genotype consensus. The main relevant mutations were tested in vitro. The ribozyme was conserved overall, with a hyper-conserved region between nt 715-745. No difference in QS was observed over time. The most variable region was between nt 739-769. Thirteen mutations were observed, with three showing a higher frequency: T23C, T69C and C64 deletion. This last strongly reduced HDV replication by more than 1 log in vitro. HDV Ribozyme QS was generally highly conserved and was maintained during follow-up. The most conserved portion may be a valuable target for a gene-silencing strategy. The presence of the C64 deletion may strongly impair viral replication, as it is a potential mechanism of viral persistence.

Hepatitis-D Virus Infection Is Not Impaired by Innate Immunity but Increases Cytotoxic T-Cell Activity

Approximately 70 million humans worldwide are affected by chronic hepatitis D, which rapidly leads to liver cirrhosis and hepatocellular carcinoma due to chronic inflammation. The triggers and consequences of this chronic inflammation, induced by co-infection with the hepatitis D virus (HDV) and the hepatitis B virus (HBV), are poorly understood. Using CRISPR technology, we characterized the recognition of HDV mono- and co-infection by intracellular innate immunity and determined its influence on the viral life cycle and effector T-cell responses using different HBV and HDV permissive hepatoma cell lines. We showed that HDV infection is detected by MDA5 and -after a lag phase -induces a profound type I interferon response in the infected cells. The type I interferon response, however, was not able to suppress HDV replication or spread, thus providing a persistent trigger. Using engineered T-cells directed against the envelope proteins commonly used by HBV and HDV, we found that HDV immune recognition enhanced T-cell cytotoxicity. Interestingly, the T-cell effector function was enhanced independently of antigen presentation. These findings help to explain immune mediated tissue damage in chronic hepatitis D patients and indicate that combining innate triggers with T-cell activating therapies might allow for a curative approach.

Efficacy and safety of bulevirtide in patients with chronic hepatitis D and compensated cirrhosis

Aim. To study the efficacy and safety of bulevirtide, the HBV and HDV entry inhibitor. Materials and methods. Analysis of the results of using bulevirtide in randomized controlled open-label comparative studies MYR202 and MYR203 in 56 patients with chronic hepatitis D and compensated cirrhosis, in monotherapy and combination with pegylated interferon alpha-2a (PEG-IFN). Results. Monotherapy with bulevirtide for 24 weeks in the MYR202 study in 46 patients with compensated liver cirrhosis demonstrated: 1) a high rate of virological (100%) and biochemical response (alanine aminotransferase normalization rate 45.7%), 2) superiority of bulevirtide in efficacy over the control group (tenofovir), 3) comparability of treatment efficacy in patients with and without cirrhosis, 4) no progression of liver fibrosis with elastometry in most patients. Treatment with bulevirtide in monotherapy and combination with PEG-IFN for 48 weeks in 10 patients with compensated liver cirrhosis in the MYR203 study was accompanied by a high rate of virological response (80%) and normalization of alanine aminotransferase (70%). Bulevirtide was well tolerated, there was no deterioration in tolerability compared with patients without cirrhosis, there were no serious adverse events and cases of treatment cancellation due to adverse events. Conclusion. Bulevirtide is recommended as the first line of treatment for chronic hepatitis D in patients with compensated cirrhosis in monotherapy and combination with PEG-IFN.

The Prevalence and Serological Association of Hepatitis D Virus Genotypes in Taiwan

Hepatitis Delta Virus (HDV) is an RNA virus that requires the presence of hepatitis B surface antigen (HBsAg) to propagate into hepatocytes, with Genotype I being more prevalent globally. However, the prevalence of HDV genotypes in Taiwan is unknown. Accordingly, a cohort including 24 chronic HBV patients who received nucleos(t)ides (NUCs) between January 2002 and July 2018 was used to determine HDV genotypes and genotype specific serological association in chronic HBV carriers. HDV-positive genotypes in 18/24 (75%) males and 6/24 (25%) females were identified among chronic HBV patients. Viremia was lower in HDV-IV patients than in patients affected with other HDV genotypes (1.34 log₁₀ copies/mL vs. 3.30 log₁₀ copies/mL; p = 0.009). A logistics regression analysis revealed that HDV-IV was inversely proportional to HDV RNA (odds ratio [OR]/95% confidence intervals [CI]: 0.370/0.164-0.830; p = 0.017). The serologic association study indicated lower levels of creatinine (p = 0.047) and HDV-RNA (p = 0.009) in the HDV-IV group than the non-HDV-IV group but did not indicate any significant differences in the AST, ALT, bilirubin levels or other laboratory test factors. The three genotypes evident in Taiwan were HDV-I (4/24, 16.7%), HDV-II (6/24, 25.0%), and HDV-IV (14/24, 58.3%), and HDV-IV is the predominant HDV genotype in Taiwan. These results anticipate a clear understanding of HDV genotype serological association in chronic HBV carriers.

Hepatitis D Review: Challenges for the Resource-Poor Setting

Hepatitis D is the smallest virus known to infect humans, the most aggressive, causing the most severe disease. It is considered a satellite or defective virus requiring the hepatitis B surface antigen (HBsAg) for its replication with approximately 10–70 million persons infected. Elimination of hepatitis D is, therefore, closely tied to hepatitis B elimination. There is a paucity of quality data in many resource-poor areas. Despite its aggressive natural history, treatment options for hepatitis D to date have been limited and, in many places, inaccessible. For decades, Pegylated interferon alpha (Peg IFN α) offered limited response rates (20%) where available. Developments in understanding viral replication pathways has meant that, for the first time in over three decades, specific therapy has been licensed for use in Europe. Bulevirtide (Hepcludex^®) is an entry inhibitor approved for use in patients with confirmed viraemia and compensated disease. It can be combined with Peg IFN α and/or nucleos(t)ide analogue for hepatitis B. Early reports suggest response rates of over 50% with good tolerability profile. Additional agents showing promise include the prenylation inhibitor lonafarnib, inhibitors of viral release (nucleic acid polymers) and better tolerated Peg IFN lambda (λ). These agents remain out of reach for most resource limited areas where access to new therapies are delayed by decades. strategies to facilitate access to care for the most vulnerable should be actively sought by all stakeholders.

Current situation of viral hepatitis in Egypt

An estimated 8-10 million people suffer from viral hepatitis in Egypt. Hepatitis A virus (HAV) and hepatitis E virus (HEV) are the major causes of viral hepatitis in Egypt as 50% or more of the Egyptian population are already exposed to HAV infection by the age of 15. In addition, over 60% of the Egyptian population test seropositive for anti-HEV in the first decade of life. HEV mainly causes self-limiting hepatitis; however, cases of fulminant hepatitis and liver failure were reported in Egypt. Hepatitis B virus (HBV), hepatitis C virus (HCV), and hepatitis D virus (HDV) are the main causes of chronic hepatitis, liver cirrhosis, and liver cancer (hepatocellular carcinoma [HCC]) in Egypt. Globally, Egypt had the highest age-standardized death rate due to cirrhosis from 1990 to 2017. The prevalence rate of HBV (1.3%-1.5%) has declined after national infantile immunization. Coinfection of HBV patients with HDV is common in Egypt because HDV antibodies (IgG) vary in range from 8.3% to 43% among total HBV patients. After the conduction of multiple national programs to control HCV infection, a lower rate of HCV prevalence (4.6%) was recently reported. Data about the incidence of HCV after treatment with direct antiviral agents (DAAs) are lacking. An HCC incidence of 29/1000/year in cirrhotic patients after DAA treatment is reported. A higher rate of infiltrative pattern among HCC patients after DAA treatment is also recognized. Viral hepatitis is one of the major public health concerns in Egypt that needs more attention and funding from health policymakers.

Identification of hepatitis delta superinfection when investigating transaminitis in HIV/hepatitis B virus co-infection

Hepatitis delta virus (HDV) is a highly pathogenic virus which can cause rapidly progressive liver disease in individuals with chronic hepatitis B virus and for which treatment options are limited. The incidence of sexually transmitted HDV infection is unknown. Here we report the case of a HDV seronegative man with pre-existent HIV/hepatitis B virus, taking effective tenofovir-containing antiretroviral therapy, who experienced a significant acute transaminitis with HDV antibody seroconversion and viraemia and no other identifiable cause.

Hepatitis delta virus: From infection to new therapeutic strategies

The hepatitis delta virus (HDV) is a small RNA virus that encodes a single protein and which requires the hepatitis B virus (HBV)-encoded hepatitis B surface antigen (HBsAg) for its assembly and transmission. HBV/HDV co-infections exist worldwide and show a higher prevalence among selected groups of HBV-infected populations, specifically intravenous drug users, practitioners of high-risk sexual behaviours, and patients with cirrhosis and hepatocellular carcinoma. The chronic form of HDV-related hepatitis is usually severe and rapidly progressive. Patterns of the viral infection itself, including the status of co-infection or super-infection, virus genotypes (both for HBV and HDV), and persistence of the virus’ replication, influence the outcome of the accompanying and manifested liver disease. Unfortunately, disease severity is burdened by the lack of an effective cure for either virus type. For decades, the main treatment option has been interferon, administered as mono-therapy or in combination with nucleos(t)ide analogues. While its efficacy has been reported for different doses, durations and courses, only a minority of patients achieve a sustained response, which is the foundation of eventual improvement in related liver fibrosis. The need for an efficient therapeutic alternative remains. Research efforts towards this end have led to new treatment options that target specific steps in the HDV life cycle; the most promising among these are myrcludex B, which inhibits virus entry into hepatocytes, lonafarnib, which inhibits farnesylation of the viral-encoded L-HDAg large hepatitis D antigen, and REP-2139, which interferes with HBsAg release and assembly.

Update on the management and treatment of viral hepatitis

This review aims to summarize the current evidence on the treatment of viral hepatitis, focusing on its clinical management. Also, future treatment options and areas of potential research interest are detailed. PubMed and Scopus databases were searched for primary studies published within the last ten years. Keywords included hepatitis A virus, hepatitis B virus (HBV), hepatitis C virus, hepatitis D virus (HDV), hepatitis E virus, and treatment. Outcomes reported in the studies were summarized, tabulated, and synthesized. Significant advances in viral hepatitis treatment were accomplished, such as the advent of curative therapies for hepatitis C and the development and improvement of hepatitis A, hepatitis B, and hepatitis E vaccination. Drugs that cure hepatitis B, going beyond viral suppression, are so far unavailable; however, targeted antiviral drugs against HBV (immunomodulatory therapies and gene silencing technologies) are promising approaches to eradicating the virus. Ultimately, high vaccination coverage and large-scale test-and-treat programmes with high screening rates may eliminate viral hepatitis and mitigate their burden on health systems. The development of curative hepatitis C treatment renewed the enthusiasm for curing hepatitis B, albeit further investigation is required. Novel therapeutic options targeting HDV life cycle are currently under clinical investigation.

Bile Goes Viral

Laboratory cultivation of viruses is critical for determining requirements for viral replication, developing detection methods, identifying drug targets, and developing antivirals. Several viruses have a history of recalcitrance towards robust replication in laboratory cell lines, including human noroviruses and hepatitis B and C viruses. These viruses have tropism for tissue components of the enterohepatic circulation system: the intestine and liver, respectively. The purpose of this review is to discuss how key enterohepatic signaling molecules, bile acids (BAs), and BA receptors are involved in the replication of these viruses and how manipulation of these factors was useful in the development and/or optimization of culture systems for these viruses. BAs have replication-promoting activities through several key mechanisms: (1) affecting cellular uptake, membrane lipid composition, and endocytic acidification; (2) directly interacting with viral capsids to influence binding to cells; and (3) modulating the innate immune response. Additionally, expression of the Na+-taurocholate cotransporting polypeptide BA receptor in continuous liver cell lines is critical for hepatitis B virus entry and robust replication in laboratory culture. Viruses are capable of hijacking normal cellular functions, and understanding the role of BAs and BA receptors, components of the enterohepatic system, is valuable for expanding our knowledge on the mechanisms of norovirus and hepatitis B and C virus replication.

CircRNA circ_0006677 Inhibits the Progression and Glycolysis in Non-Small-Cell Lung Cancer by Sponging miR-578 and Regulating SOCS2 Expression

Objective: Circular RNAs (circRNAs) have been demonstrated in playing an important role in the physiological and pathological processes (such as cancer). This paper aims to clarify the role of Circ_0006677 in non–small-cell lung cancer (NSCLC) progression.

Methods: Using clinical data and in vitro cell line models, we revealed the tumor-suppressive role of circ_0006677 in lung cancer. Using the online bioinformatics tool, we predicted the target of circ_0006677 and further validated its regulatory mechanisms responsible for its tumor suppressor function in NSCLC.

Results: Circ_0006677 expression was reduced in NSCLC tissues of patients and lung cancer cells in comparison to adjacent normal tissues. Lower expression of circ_0006677 was significantly associated with poorer patient survival. Overexpression of circ_0006677 significantly inhibited the ability of NSCLC cell proliferation, migration, invasion, and glycolysis. Mechanically, circ_0006677 could inhibit NSCLC progression and glycolysis by regulating the expression of the signal transducer inhibitor SOSC2 through sponging microRNA-578 (miR-578).

Conclusion: Circ_0006677 prevents the progression of NSCLC via modulating the miR-578/SOSC2 axis.

HDV Pathogenesis: Unravelling Ariadne's Thread

Hepatitis Delta virus (HDV) lies in between satellite viruses and viroids, as its unique molecular characteristics and life cycle cannot categorize it according to the standard taxonomy norms for viruses. Being a satellite virus of hepatitis B virus (HBV), HDV requires HBV envelope glycoproteins for its infection cycle and its transmission. HDV pathogenesis varies and depends on the mode of HDV and HBV infection; a simultaneous HDV and HBV infection will lead to an acute hepatitis that will resolve spontaneously in the majority of patients, whereas an HDV super-infection of a chronic HBV carrier will mainly result in the establishment of a chronic HDV infection that may progress towards cirrhosis, liver decompensation, and hepatocellular carcinoma (HCC). With this review, we aim to unravel Ariadne’s thread into the labyrinth of acute and chronic HDV infection pathogenesis and will provide insights into the complexity of this exciting topic by detailing the different players and mechanisms that shape the clinical outcome.

AAV-HDV: An Attractive Platform for the In Vivo Study of HDV Biology and the Mechanism of Disease Pathogenesis

Hepatitis delta virus (HDV) infection causes the most severe form of viral hepatitis, but little is known about the molecular mechanisms involved. We have recently developed an HDV mouse model based on the delivery of HDV replication-competent genomes using adeno-associated vectors (AAV), which developed a liver pathology very similar to the human disease and allowed us to perform mechanistic studies. We have generated different AAV-HDV mutants to eliminate the expression of HDV antigens (HDAgs), and we have characterized them both in vitro and in vivo. We confirmed that S-HDAg is essential for HDV replication and cannot be replaced by L-HDAg or host cellular proteins, and that L-HDAg is essential to produce the HDV infectious particle and inhibits its replication. We have also found that lack of L-HDAg resulted in the increase of S-HDAg expression levels and the exacerbation of liver damage, which was associated with an increment in liver inflammation but did not require T cells. Interestingly, early expression of L-HDAg significantly ameliorated the liver damage induced by the mutant expressing only S-HDAg. In summary, the use of AAV-HDV represents a very attractive platform to interrogate in vivo the role of viral components in the HDV life cycle and to better understand the mechanism of HDV-induced liver pathology.

Genomics of Viral Hepatitis-Associated Liver Tumors

Virus-related liver carcinogenesis is one of the main contributors of cancer-related death worldwide mainly due to the impact of chronic hepatitis B and C infections. Three mechanisms have been proposed to explain the oncogenic properties of hepatitis B virus (HBV) infection: induction of chronic inflammation and cirrhosis, expression of HBV oncogenic proteins, and insertional mutagenesis into the genome of infected hepatocytes. Hepatitis B insertional mutagenesis modifies the function of cancer driver genes and could promote chromosomal instability. In contrast, hepatitis C virus promotes hepatocellular carcinoma (HCC) occurrence mainly through cirrhosis development whereas the direct oncogenic role of the virus in human remains debated. Finally, adeno associated virus type 2 (AAV2), a defective DNA virus, has been associated with occurrence of HCC harboring insertional mutagenesis of the virus. Since these tumors developed in a non-cirrhotic context and in the absence of a known etiological factor, AAV2 appears to be the direct cause of tumor development in these patients via a mechanism of insertional mutagenesis altering similar oncogenes and tumor suppressor genes targeted by HBV. A better understanding of virus-related oncogenesis will be helpful to develop new preventive strategies and therapies directed against specific alterations observed in virus-related HCC.

Role of hepatitis D virus infection in development of hepatocellular carcinoma among chronic hepatitis B patients treated with nucleotide/nucleoside analogues

Hepatitis D virus (HDV) infection increases the risk of hepatocellular carcinoma (HCC) in the natural course of chronic hepatitis B (CHB) patients. Its role in patients treated with nucleotide/nucleoside analogues (NAs) is unclear. We aimed to study the role of hepatitis D in the development of HCC in CHB patients treated with NAs. Altogether, 1349 CHB patients treated with NAs were tested for anti-HDV antibody and RNA. The incidence and risk factors of HCC development were analyzed. Rates of anti-HDV and HDV RNA positivity were 2.3% and 1.0%, respectively. The annual incidence of HCC was 1.4 per 100 person-years after a follow-up period of over 5409.5 person-years. The strongest factor association with HCC development was liver cirrhosis (hazard ratio [HR]/95% confidence interval [CI] 9.98/5.11-19.46, P < 0.001), followed by HDV RNA positivity (HR/ CI 5.73/1.35-24.29, P = 0.02), age > 50 years old (HR/CI 3.64/2.03-6.54, P < 0.001), male gender (HR/CI 2.69/1.29-5.60, P: 0.01), and body mass index (BMI, HR/CI 1.11/1.03-1.18, P = 0.004). The 5-year cumulative incidence of HCC was 7.3% for patients with HDV RNA negativity compared to that of 22.2% for patients with HDV RNA positivity (P = 0.01). In the subgroup of cirrhotic patients, the factors associated with HCC development were HDV RNA positivity (HR/CI 4.45/1.04-19.09, P = 0.04) and BMI (HR/CI 1.11/1.03-1.19, P = 0.01). HDV viremia played a crucial role in HCC development in CHB patients who underwent NA therapy.

Hepatitis D virus and liver transplantation: Indications and outcomes

Hepatitis D virus (HDV) is a dependent virus that relies on hepatitis B virus for its replication and transmission. Chronic hepatitis D is a severe form of viral hepatitis that can result in end stage liver disease. Currently, pegylated interferon alpha is the only approved therapy for chronic HDV infection and is associated with significant side effects. Liver transplantation (LT) is the only treatment option for patients with end-stage liver disease, hepatocellular carcinoma, or fulminant hepatitis due to coinfection with HDV. As LT for HDV and hepatitis B virus coinfection is uncommon in the United States, most data on the long-term impact of LT on HDV are from international centers. In this review, we discuss the indications and results of LT with treatment options in HDV patients.

From national HBV and HDV screenings to vaccination and treatment in healthcare workers: The Mauritanian pilot study

OBJECTIVES

Hepatitis B and D infections are highly endemic in Mauritania, with prevalences ranging from 10 to 20%. With the present prospective transversal pilot study, we aimed to evaluate the prevalences of HBV, HCV, and HDV infections in healthcare workers (HCWs), and offer treatment or vaccination as required.

METHODS

At inclusion, each HCW was screened for anti-HBc Ab (followed by HBsAg assay when positive). Additional biological analyses were performed for HBsAg + cases. Depending on the results, HBV vaccination or anti-viral treatment was offered.

RESULTS

A total of 3,857 HCWs were included, of whom 1,363 tested negative for anti-HBc Ab and received full vaccination. Of the 2,494 HCWs who were positive for anti-HBc Ab, 1,246 were positive for anti-HBs Ab and 418 were positive for HBsAg. Three HCWs were positive for HBeAg; 66 and 18 had HBV DNA levels respectively > 2,000 and > 20,000 IU/mL; and 48 were positive for anti-HDV Ab among whom 10 were positive for HDV RNA. HCV prevalence was 0.5%. Only seven HCWs fulfilled the criteria for treatment and five of them were treated.

CONCLUSION

Few HCWs in Mauritania are immunised against HBV. The prevalences of anti-HBc Ab and HBsAg observed in this work were similar to those observed in our earlier works, whereas prevalence of active HDV infection was less high. HBV and HDV infections are a serious health concern in Mauritania. New recommendations developed in accordance with WHO guidelines should include mandatory HBV screening and immunisation for HCWs.

Genotype distribution, clinical characteristics, and racial differences observed in chronic hepatitis C patients in Pingtung, Taiwan

BACKGROUND

The World Health Organization (WHO) set out to eliminate hepatitis C virus (HCV) infection by 2030, a goal Taiwan might achieve before 2025. Using effective direct antiviral agents (DAAs) against chronic hepatitis C (CHC) in Taiwan, the treatment of CHC has been initiated in rural areas. Here, we aimed to elucidate the clinical and virological characteristics of HCV infection, and the treatment efficacy of DAAs in patients from Pingtung county in southern Taiwan.

METHODS

A total of 152 chronic hepatitis patients treated with DAAs were consecutively enrolled. Baseline characteristics and therapeutic efficacy were evaluated.

RESULTS

HCV genotype 2 was the most common viral genotype (39.5%), followed by 1b (36.8%), 6 (10.5%), and 1a (9.2%). The sustained virological response (SVR) rate was 98.7%. Hakka patients accounted for 22.4% of the study cohort, of which 14.7% had HCV genotype 6. There were no differences in clinical characteristics between Hakka and non-Hakka patients. Patients with HCV genotype 6 were younger in age (OR/CI: 0.95/0.91-1.00, p = 0.04) and composed of more people who inject drugs (PWID) (OR/CI: 17.6/3.6-85.5, p <0.001), when compared with other patients.

CONCLUSION

We demonstrated that DAA therapy can achieve a 98.7% SVR rate among CHC patients in Pingtung county of southern Taiwan, with a relative higher prevalence of genotype 6. The most important factor attributed to genotype 6 infection was PWID.

Molecular Phylogenetics of Hepatitis D Virus in New Zealand and the Implications for Pacific Island Countries

Hepatitis delta virus (HDV) is considered a satellite virus that requires hepatitis B virus surface antigen for infectivity. HDV is endemic in some Pacific Island (PI) countries, including Kiribati and Nauru, with a unique genotype 1, "Pacific clade." The aims of this study were to determine the HDV genotypes in New Zealand and investigate the link of strains to other PI countries and the rest of the world through phylogenetics. Sequencing and phylogenetic analyses were performed on 16 HDV-positive serum samples from 14 individuals collected between 2009 and 2014 at Auckland Hospital. Thirteen of 14 strains were confirmed as genotype 1 and 1 was genotype 5. Eleven of the 13 genotype 1 strains clustered with the Pacific clade. These were isolated from subjects born in Samoa, Kiribati, Tuvalu, and Niue. Another genotype 1 strain isolated from a Maori health-care worker clustered most closely with a European strain. There was an African genotype 1 and genotype 5 from African-born subjects with HIV coinfection. This study supports the probable transmission of HDV Pacific clade around the PI from Micronesia to Polynesia. The data also confirm the need to screen hepatitis B surface antigen-positive individuals for HDV.