Analysis of Replication, Cell Division-Mediated Spread, and HBV Envelope Protein-Dependent Pseudotyping of Three Mammalian Delta-like Agents.

The human hepatitis delta virus (HDV) is a satellite RNA virus that depends on hepatitis B virus (HBV) surface proteins (HBsAg) to assemble into infectious virions targeting the same organ (liver) as HBV. Until recently, the evolutionary origin of HDV remained largely unknown. The application of bioinformatics on whole sequence databases lead to discoveries of HDV-like agents (DLA) and shed light on HDV's evolution, expanding our understanding of HDV biology. DLA were identified in heterogeneous groups of vertebrates and invertebrates, highlighting that the evolution of HDV, represented by eight distinct genotypes, is broader and more complex than previously foreseen. In this study, we focused on the characterization of three mammalian DLA discovered in woodchuck (Marmota monax), white-tailed deer (Odocoileus virginianus), and lesser dog-like bat (Peropteryx macrotis) in terms of replication, cell-type permissiveness, and spreading pathways. We generated replication-competent constructs expressing 1.1-fold over-length antigenomic RNA of each DLA. Replication was initiated by transfecting the cDNAs into human (HuH7, HeLa, HEK293T, A549) and non-human (Vero E6, CHO, PaKi, LMH) cell lines. Upon transfection and replication establishment, none of the DLA expressed a large delta antigen. A cell division-mediated viral amplification assay demonstrated the capability of non-human DLA to replicate and propagate in hepatic and non-hepatic tissues, without the requirement of envelope proteins from a helper virus. Remarkably L-HDAg but not S-HDAg from HDV can artificially mediate envelopment of WoDV and DeDV ribonucleoproteins (RNPs) by HBsAg to form infectious particles, as demonstrated by co-transfection of HuH7 cells with the respective DLA expression constructs and a plasmid encoding HBV envelope proteins. These chimeric viruses are sensitive to HDV entry inhibitors and allow synchronized infections for comparative replication studies. Our results provide a more detailed understanding of the molecular biology, evolution, and virus-host interaction of this unique group of animal viroid-like agents in relation to HDV.

Investigating the Genetic Diversity of Hepatitis Delta Virus in Hepatocellular Carcinoma (HCC): Impact on Viral Evolution and Oncogenesis in HCC.

Hepatitis delta virus (HDV), an RNA virus with two forms of the delta antigen (HDAg), relies on hepatitis B virus (HBV) for envelope proteins essential for hepatocyte entry. Hepatocellular carcinoma (HCC) ranks third in global cancer deaths, yet HDV's involvement remains uncertain. Among 300 HBV-associated HCC serum samples from Taiwan's National Health Research Institutes, 2.7% (8/300) tested anti-HDV positive, with 62.7% (5/8) of these also HDV RNA positive. Genotyping revealed HDV-2 in one sample, HDV-4 in two, and two samples showed mixed HDV-2/HDV-4 infection with RNA recombination. A mixed-genotype infection revealed novel mutations at the polyadenylation signal, coinciding with the ochre termination codon for the L-HDAg. To delve deeper into the possible oncogenic properties of HDV-2, the predominant genotype in Taiwan, which was previously thought to be less associated with severe disease outcomes, an HDV-2 cDNA clone was isolated from HCC for study. It demonstrated a replication level reaching up to 74% of that observed for a widely used HDV-1 strain in transfected cultured cells. Surprisingly, both forms of HDV-2 HDAg promoted cell migration and invasion, affecting the rearrangement of actin cytoskeleton and the expression of epithelial-mesenchymal transition markers. In summary, this study underscores the prevalence of HDV-2, HDV-4, and their mixed infections in HCC, highlighting the genetic diversity in HCC as well as the potential role of both forms of the HDAg in HCC oncogenesis.

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.

Hepatocyte Intrinsic Innate Antiviral Immunity against Hepatitis Delta Virus Infection: The Voices of Bona Fide Human Hepatocytes.

The pathogenesis of viral infection is attributed to two folds: intrinsic cell death pathway activation due to the viral cytopathic effect, and immune-mediated extrinsic cellular injuries. The immune system, encompassing both innate and adaptive immunity, therefore acts as a double-edged sword in viral infection. Insufficient potency permits pathogens to establish lifelong persistent infection and its consequences, while excessive activation leads to organ damage beyond its mission to control viral pathogens. The innate immune response serves as the front line of defense against viral infection, which is triggered through the recognition of viral products, referred to as pathogen-associated molecular patterns (PAMPs), by host cell pattern recognition receptors (PRRs). The PRRs-PAMPs interaction results in the induction of interferon-stimulated genes (ISGs) in infected cells, as well as the secretion of interferons (IFNs), to establish a tissue-wide antiviral state in an autocrine and paracrine manner. Cumulative evidence suggests significant variability in the expression patterns of PRRs, the induction potency of ISGs and IFNs, and the IFN response across different cell types and species. Hence, in our understanding of viral hepatitis pathogenesis, insights gained through hepatoma cell lines or murine-based experimental systems are uncertain in precisely recapitulating the innate antiviral response of genuine human hepatocytes. Accordingly, this review article aims to extract and summarize evidence made possible with bona fide human hepatocytes-based study tools, along with their clinical relevance and implications, as well as to identify the remaining gaps in knowledge for future investigations.

Protective role of RIPK1 scaffolding against HDV-induced hepatocyte cell death and the significance of cytokines in mice.

Hepatitis delta virus (HDV) infection represents the most severe form of human viral hepatitis; however, the mechanisms underlying its pathology remain incompletely understood. We recently developed an HDV mouse model by injecting adeno-associated viral vectors (AAV) containing replication-competent HBV and HDV genomes. This model replicates many features of human infection, including liver injury. Notably, the extent of liver damage can be diminished with anti-TNF-α treatment. Here, we found that TNF-α is mainly produced by macrophages. Downstream of the TNF-α receptor (TNFR), the receptor-interacting serine/threonine-protein kinase 1 (RIPK1) serves as a cell fate regulator, playing roles in both cell survival and death pathways. In this study, we explored the function of RIPK1 and other host factors in HDV-induced cell death. We determined that the scaffolding function of RIPK1, and not its kinase activity, offers partial protection against HDV-induced apoptosis. A reduction in RIPK1 expression in hepatocytes through CRISPR-Cas9-mediated gene editing significantly intensifies HDV-induced damage. Contrary to our expectations, the protective effect of RIPK1 was not linked to TNF-α or macrophage activation, as their absence did not alter the extent of damage. Intriguingly, in the absence of RIPK1, macrophages confer a protective role. However, in animals unresponsive to type-I IFNs, RIPK1 downregulation did not exacerbate the damage, suggesting RIPK1's role in shielding hepatocytes from type-I IFN-induced cell death. Interestingly, while the damage extent is similar between IFNα/ßR KO and wild type mice in terms of transaminase elevation, their cell death mechanisms differ. In conclusion, our findings reveal that HDV-induced type-I IFN production is central to inducing hepatocyte death, and RIPK1's scaffolding function offers protective benefits. Thus, type-I IFN together with TNF-α, contribute to HDV-induced liver damage. These insights may guide the development of novel therapeutic strategies to mitigate HDV-induced liver damage and halt disease progression.

HepG2BD: A Novel and Versatile Cell Line with Inducible HDV Replication and Constitutive HBV Expression.

Individuals chronically infected with hepatitis B virus (HBV) and hepatitis Delta virus (HDV) present an increased risk of developing cirrhosis and hepatocellular carcinoma in comparison to HBV mono-infected individuals. Although HDV only replicates in individuals coinfected or superinfected with HBV, there is currently no in vitro model that can stably express both viruses simultaneously, mimicking the chronic infections seen in HBV/HDV patients. Here, we present the HepG2BD cell line as a novel in vitro culture system for long-term replication of HBV and HDV. HepG2BD cells derive from HepG2.2.15 cells in which a 2 kb HDV cDNA sequence was inserted into the adeno-associated virus safe harbor integration site 1 (AAVS1) using CRISPR-Cas9. A Tet-Off promoter was placed 5' of the genomic HDV sequence for reliable initiation/repression of viral replication and secretion. HBV and HDV replication were then thoroughly characterized. Of note, non-dividing cells adopt a hepatocyte-like morphology associated with an increased production of both HDV and HBV virions. Finally, HDV seems to negatively interfere with HBV in this model system. Altogether, HepG2BD cells will be instrumental to evaluate, in vitro, the fundamental HBV-HDV interplay during simultaneous chronic replication as well as for antivirals screening targeting both viruses.

Hepatitis B Delta: assessment of the knowledge and practices of hepato-gastroenterologists practicing in non-academic settings in France.

BACKGROUND: Data on the management of Hepatitis B-Delta (HB-D) by hepatogastroenterologists (HGs) practicing in nonacademic hospitals or private practices are unknown in France. OBJECTIVE: We aimed to evaluate the knowledge and practices of HGs practicing in nonacademic settings regarding HB-D. METHODS: A Google form document was sent to those HGs from May to September 2021. RESULTS: A total of 130 HGs (mean age, 45 years) have participated in this survey. Among HBsAg-positive patients, Delta infection was sought in only 89% of cases. Liver fibrosis was assessed using FibroScan in 77% of the cases and by liver biopsy in 81% of the cases. A treatment was proposed for patients with >F2 liver fibrosis in 49% of the cases regardless of transaminase levels and for all the patients by 39% of HGs. Responding HGs proposed a treatment using pegylated interferon in 50% of cases, bulevirtide in 45% of cases and a combination of pegylated interferon and bulevirtide in 40.5% of cases. Among the criteria to evaluate the treatment efficacy, a decrease or a normalization of transaminases was retained by 89% of responding HGs, a reduction of liver fibrosis score for 70% of them, an undetectable delta RNA and HBsAg for 55% of them and a 2 log 10 decline in delta viremia for 62% of the cases. CONCLUSION: Hepatitis Delta screening was not systematically performed in HBsAg-positive patients despite the probable awareness and knowledge of the few responders who were able to prescribe treatments of hepatitis delta.

Major open questions in the hepatitis B and D field - Proceedings of the inaugural International emerging hepatitis B and hepatitis D researchers workshop.

The early and mid-career researchers (EMCRs) of scientific communities represent the forefront of research and the future direction in which a field takes. The opinions of this key demographic are not commonly aggregated to audit fields and precisely demonstrate where challenges lie for the future. To address this, we initiated the inaugural International Emerging Researchers Workshop for the global Hepatitis B and Hepatitis D scientific community (75 individuals). The cohort was split into small discussion groups and the significant problems, challenges, and future directions were assessed. Here, we summarise the outcome of these discussions and outline the future directions suggested by the EMCR community. We show an effective approach to gauging and accumulating the ideas of EMCRs and provide a succinct summary of the significant gaps remaining in the Hepatitis B and Hepatitis D field.

Dismantling Barriers to Hepatitis B and Delta Screening, Prevention, and Linkage to Care among the PWUD Community in Philadelphia.

The prevalence of hepatitis B and delta viruses (HBV/HDV) among people who use drugs (PWUD) remains largely unknown. In the context of one Philadelphia-based harm reduction organization (HRO), this study aimed to assess HBV/HDV prevalence and facilitate linkage to care. Participants completed a demographic HBV/HDV risk factor survey and were screened for HBV and reflexively for HDV if positive for HBV surface antigen or isolated core antibody. Fisher's exact tests and regression were used to understand relationships between risks and HBV blood markers. Of the 498 participants, 126 (25.3%) did not have hepatitis B immunity, 52.6% had been vaccinated against HBV, and 17.9% had recovered from a past infection. Eleven (2.2%) participants tested positive for isolated HBV core antibody, 10 (2.0%) for HBV surface antigen, and one (0.2%) for HDV antibody. History of incarceration was associated with current HBV infection, while transactional sex and experience of homelessness were predictive of previous exposure. This study found high rates of current and past HBV infection, and a 10% HBV/HDV co-infection rate. Despite availability of vaccine, one quarter of participants remained vulnerable to infection. Findings demonstrate the need to improve low-threshold HBV/HDV screening, vaccination, and linkage to care among PWUD. The study also identified gaps in the HBV/HDV care cascade, including lack of point-of-care diagnostics and lack of support for HROs to provide HBV services.

Addressing hepatitis delta in primary care practices in the US: a narrative review.

OBJECTIVE: Infection with the hepatitis delta virus (HDV), a unique RNA virus that requires hepatitis B virus (HBV) antigens for its assembly, replication, and transmission, causes severe viral hepatitis. Compared to HBV monoinfection, HDV infection increases the risk of severe liver disease, necessity for liver transplant, and mortality. Global HDV prevalence estimates vary from 5% to 15% among persons with HBV, but screening guidelines for HDV are inconsistent; some recommend risk-based screening, while others recommend universal screening for all people with HBV. Among primary care providers (PCPs) in the US, there is a lack of awareness and/or insufficient adherence to current recommendations for the screening of HDV infection and management of chronic HDV. METHODS: Publications were obtained by conducting literature searches between July and August 2022 using the PubMed database and by manual searches of the retrieved literature for additional references. Information was synthesized to highlight HDV screening and management strategies for PCPs. Best practices for PCPs based on current guidelines and comanagement strategies for patients with HBV and HDV infection were summarized. RESULTS: We recommend universal screening for HDV in patients positive for hepatitis B surface antigen. Confirmed HDV infection should prompt evaluation by a liver specialist, if available, with whom the PCP can comanage the patient. PCPs should counsel patients on the expected course of the disease, lifestyle factors that may influence liver health, need for consistent disease monitoring and follow-up, and risk of disease transmission. Screening is suggested for sexual partners, household contacts, and family members, with HBV immunization recommended for those found to be susceptible. There are currently no US Food and Drug Administration-approved therapies for HDV infection; thus, management is limited to treatments for chronic HBV infection plus long-term monitoring of liver health. CONCLUSIONS: PCPs can be a valuable point of care for patients to access HDV/HBV screening, HBV immunization, and education, and can comanage patients with HBV and/or HDV infection.

Hepatitis delta virus (HDV) infection only occurs in the presence of hepatitis B virus (HBV) infection. People with an HDV infection are at higher risk for severe liver disease, liver transplant, and death compared to those who only have an HBV infection. The estimated global prevalence of HDV infection ranges from 5% to 15% among people living with HBV. These measurements vary due to different study methods, inconsistent HDV screening guidelines, and patient risk factors for infection.In the US, primary care providers (PCPs) play an important role in improving community access to HDV information and testing. However, poor funding and inadequate resources have created a lack of awareness and insufficient adherence by PCPs to current recommendations for screening and management of HDV infection. This narrative review aims to fill this gap by providing an overview of HDV infection, patient risk factors, and practice guidelines for PCPs.The recommendations for PCPs in this review include providing universal screening for HDV to people with an HBV infection, especially those at high risk. PCPs can educate and comanage patients with liver specialists. Topics to discuss with patients include expected disease outcomes, lifestyle factors that may influence liver health, and the need for consistent follow-up appointments. Patient risk of disease transmission can also be discussed to identify sexual partners, household contacts, and family members who will need screening and HBV vaccination. While there are no FDA-approved therapies for treating HDV infection, we provide an overview of available and emerging HDV treatments.

A regular screening for hepatitis delta virus among chronic hepatitis B carriers improves the diagnostic of this infection and of subsequent cirrhosis development.

BACKGROUND AND OBJECTIVE: The prevalence of Hepatitis Delta Virus (HDV) is underestimated and the assessment of fibrosis is recommended for this infection. We tested the diagnostic impact of an annual screening for HDV serology in Hepatitis B Surface Antigen (HBs Ag) chronic carriers and followed the progression of fibrosis in these patients. METHODS: Between January 2014 and October 2021, we annually tested all chronic HBs Ag-positive patients for HDV antibody (HDV Ab). Each HDV Ab positive patient underwent annually repeated elastometry. Patients with detectable HDV RNA levels (group 1) were compared to those with undetectable HDV RNA (group 2). RESULTS: We identified 610 chronic HBs Ag-positive patients, and repeated screening for HDV Ab was performed in 534 patients. Sixty (11%) patients were HDV Ab positive at baseline and were considered as "coinfected". Seven cases of HDV superinfection were diagnosed through repeated screening. In co-infected patients, cirrhosis was initially diagnosed in 12/60 patients and developed in six patients during follow-up. HDV RNA PCR was performed in 57/67 patients and 27 had detectable levels (group 1). Cumulative incidence of cirrhosis at 7 years was 13.8% (95% CI 0-30) in group 1 and 0 (95% CI 0-0) in group 2 (p = 0.026). CONCLUSION: A systematic screening for HDV in chronic HB Ag carriers revealed a high prevalence of HDV Ab. Repeated serological screening enables the diagnosis of superinfections in asymptomatic patients. Regular assessment of fibrosis using elastometry leads to the identification of incidental cirrhosis in patients with detectable HDV RNA.

[Diagnosis and treatment of viral hepatitis B and D in 2024]. / Diagnostik und Therapie der Virushepatitis B und D im Jahr 2024.

Despite the availability of vaccines, hepatitis B remains a significant cause of fulminant hepatitis, liver cirrhosis and hepatocellular carcinoma worldwide. The increase in reported hepatitis B cases in Germany is attributed to factors such as immigration and the hepatitis B surface antigen (HBsAg) screening introduced in 2020 as part of health check-ups. The indication for treatment depends on various factors, including the level of hepatitis B virus (HBV) DNA and inflammatory activity. Nucleos(t)ide analogues are the preferred treatment option, but functional cure, defined as HBsAg loss, is rare. In principle, treatment with nucleos(t)ide analogues should usually be discontinued after loss of HBsAg, but can be stopped earlier under certain conditions and is currently the subject of ongoing research. Pregnancy and immunosuppression in the context of hepatitis B require special attention. In addition, a possible hepatitis D virus co-infection must always be taken into account, which is why every HBsAg-positive person should be tested for anti-HDV. Since 2020, the entry inhibitor bulevirtide has become a new treatment option alongside pegylated interferon alfa, which represents a significant advance in the treatment landscape.

The elimination of hepatitis D as a public health problem: Needs and challenges.

Infection with hepatitis D virus leads to liver disease and cancer most rapidly of all hepatitis viruses. However, knowledge about hepatitis D remains poor and the burden and impact are underestimated, even though some 12-15 million people mainly in low- and middle-income countries may be affected. Its epidemiology is changing, with increasing migration leading to increased risks of infection and disease. A recent Viral Hepatitis Prevention Board meeting reviewed the current epidemiological status, improvements in diagnostic testing, advances in the development of novel antiviral agents in phase III trials and the need for a greater public health response, such as new guidelines and recommended testing of all people newly identified as infected with hepatitis B virus for hepatitis D virus infection. It identified issues and needs for attention with regard to prevention, diagnosis and treatment.

Five-year follow-up of 96 weeks peginterferon plus tenofovir disoproxil fumarate in hepatitis D.

BACKGROUND & AIMS: Until recently, pegylated interferon-alfa-2a (PEG-IFNa) therapy was the only treatment option for patients infected with hepatitis D virus (HDV). Treatment with PEG-IFNa with or without tenofovir disoproxil fumarate (TDF) for 96 weeks resulted in HDV RNA suppression in 44% of patients at the end of therapy but did not prevent short-term relapses within 24 weeks. The virological and clinical long-term effects after prolonged PEG-IFNa-based treatment of hepatitis D are unknown. METHODS: In the HIDIT-II study patients (including 40% with liver cirrhosis) received 180 µg PEG-IFNa weekly plus 300 mg TDF once daily (n = 59) or 180 µg PEG-IFNa weekly plus placebo (n = 61) for 96 weeks. Patients were followed until week 356 (5 years after end of therapy). RESULTS: Until the end of follow-up, 16 (13%) patients developed liver-related complications (PEG-IFNa + TDF, n = 5 vs PEG-IFNa + placebo, n = 11; p = .179). Achieving HDV suppression at week 96 was associated with decreased long-term risk for the development of hepatocellular carcinoma (p = .04) and hepatic decompensation (p = .009). Including complications irrespective of PEG-IFNa retreatment status, the number of patients developing serious complications was similar with (3/18) and without retreatment with PEG-IFNa (16/102, p > .999) but was associated with a higher chance of HDV-RNA suppression (p = .024, odds ratio 3.9 [1.3-12]). CONCLUSIONS: Liver-related clinical events were infrequent and occurred less frequently in patients with virological responses to PEG-IFNa treatment. PEG-IFNa treatment should be recommended to HDV-infected patients until alternative therapies become available. Retreatment with PEG-IFNa should be considered for patients with inadequate response to the first course of treatment. CLINICAL TRIAL REGISTRATION: NCT00932971.

Ergosterol peroxide blocks HDV infection as a novel entry inhibitor by targeting human NTCP receptor.

Hepatitis D virus (HDV), which co-infects or superinfects patients with hepatitis B virus, is estimated to affect 74 million people worldwide. Chronic hepatitis D is the most severe form of viral hepatitis and can result in liver cirrhosis, liver failure, and hepatocellular carcinoma (HCC). Currently, there are no efficient HDV-specific drugs. Therefore, there is an urgent need for novel HDV therapies that can achieve a functional cure or even eliminate the viral infection. In the HDV life cycle, agents targeting the entry step of HDV infection preemptively reduce the intrahepatic viral RNA. Human sodium taurocholate co-transporting polypeptide (hNTCP), a transporter of bile acids on the plasma membrane of hepatocytes, is an essential entry receptor of HDV and is a promising molecular target against HDV infection. Here, we investigated the effect of ergosterol peroxide (EP) on HDV infection in vitro and in vivo. EP inhibited HDV infection of hNTCP-expressing dHuS-E/2 hepatocytes by interrupting the early fusion/endocytosis step of HDV entry. Furthermore, molecular modeling suggested that EP hinders LHBsAg binding to hNTCP by blocking access to S267 and V263. In addition, we generated hNTCP-expressing transgenic (Tg) C57BL/6 mice using the Cre/loxP system for in vivo study. EP reduced the liver HDV RNA level of HDV-challenged hNTCP-Cre Tg mice. Intriguingly, EP downregulated the mRNA level of liver IFN-γ. We demonstrate that EP is a bona fide HDV entry inhibitor that acts on hNTCP and has the potential for use in HDV therapies.

Determinants of worse liver-related outcome according to HDV infection among HBsAg positive persons living with HIV: Data from the ICONA cohort.

OBJECTIVES: We aimed to study hepatitis D virus (HDV) prevalence and risk of progression to severe liver-related events (SLRE) in HBsAg positive people living with HIV (PLWH) in Italy; role of HDV-RNA copy levels, HCV coinfection and nadir CD4 counts were also investigated. METHODS: People living with HIV (PLWH) from Italian Foundation cohort Naïve antiretrovirals (ICONA) with available HBsAg and HDV Ab were enrolled. HBsAg, HDV Ab, HDV-RNA and HDV genotypes were tested. PRIMARY END-POINT: time from first HDV screening to Severe Liver Related Events (SLRE: decompensated cirrhosis, liver transplantation, HCC). Fine-grey regression models were used to evaluate the association of HDV Ab, HDV-RNA, HDV/HCV coinfection, CD4 nadir and outcome. Secondary end-points: time to SLRE or death; HDV Ab and HDV-RNA prevalence. RESULTS: A total of 152/809 (18.8%) HBsAg positive PLWH showed HDV Ab reactivity; 63/93 (67.7%) were HDV-RNA positive. Being male, persons who inject drugs (PWID), HCV Ab positive, with FIB-4 > 3.25 were independent factors of HDV Ab positivity. In a median follow-up of 5 years, 37 PLWH (4.1% at 5-year) developed SLRE and 97 (12.0%) reached the SLRE or death end-point. HDV-RNA positive (independently from HDV-RNA copy level) PLWH had a 4.6-fold (95%CI 2.0-10.5) higher risk of SLRE than HDV negatives. PLWH positive for both HCV Ab and HDV Ab showed the highest independent risk of SLRE (ASHR: 11.9, 95%CI: 4.6-30.9 vs. HCV neg/HDV neg). Nadir CD4 < 200/mL was associated with SLRE (ASHR: 3.9, 95% 1.0-14.5). CONCLUSIONS: One-fifth of the HBsAg positive PLWH harbour HDV infection, and are at high risk of progression to advanced liver disease. HCV contributes to worse outcomes. This population needs urgently effective treatments.

Hepatitis D infection induces IFN-ß-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-ß 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.

Prevalence of hepatitis D virus infection among patients with chronic hepatitis B infection in a tertiary care centre in Thailand.

Knowledge about the epidemiology of hepatitis D virus (HDV) is essential for effective screening and management. Our study aimed to update the prevalence of HDV infection among patients with hepatitis B virus (HBV) infection at hepatology clinics in Thailand. We enrolled HBV-infected patients from hepatology clinics at King Chulalongkorn Memorial Hospital, Bangkok, Thailand, between June 2022 and November 2023. Demographic, biochemical characteristics, and liver-related complications (LRC), including cirrhosis and hepatocellular carcinoma, were reviewed. The competitive enzyme and chemiluminescence immunoassays were used to detect anti-HDV antibodies. Real-time polymerase chain reaction (RT-PCR) was used to test for HDV RNA in anti-HDV-positive patients. The HDV genotype was identified in detectable HDV RNA samples. Of the 702 enrolled patients, four (0.6%) had positive and equivocal for both anti-HDV tests. Two (50.0%) of the four patients tested positive for HDV RNA and genotype 1 was identified; one had multiple risk factors. Anti-HDV seroprevalence was not significantly different between patients with and without LRC. In conclusion, HDV co-infection is less common in Thailand than globally. Additionally, our study identified genotype 1, the predominant HDV genotype worldwide, and observed co-infection even without LRC.

Hepatitis D: A Review.

Importance: Hepatitis D virus (HDV) infection occurs in association with hepatitis B virus (HBV) infection and affects approximately 12 million to 72 million people worldwide. HDV causes more rapid progression to cirrhosis and higher rates of hepatocellular carcinoma than HBV alone or hepatitis C virus. Observations: HDV requires HBV to enter hepatocytes and to assemble and secrete new virions. Acute HDV-HBV coinfection is followed by clearance of both viruses in approximately 95% of people, whereas HDV superinfection in an HBV-infected person results in chronic HDV-HBV infection in more than 90% of infected patients. Chronic hepatitis D causes more rapidly progressive liver disease than HBV alone. Approximately 30% to 70% of patients with chronic hepatitis D have cirrhosis at diagnosis and more than 50% die of liver disease within 10 years of diagnosis. However, recent studies suggested that progression is variable and that more than 50% of people may have an indolent course. Only approximately 20% to 50% of people infected by hepatitis D have been diagnosed due to lack of awareness and limited access to reliable diagnostic tests for the HDV antibody and HDV RNA. The HBV vaccine prevents HDV infection by preventing HBV infection, but no vaccines are available to protect those with established HBV infection against HDV. Interferon alfa inhibits HDV replication and reduces the incidence of liver-related events such as liver decompensation, hepatocellular carcinoma, liver transplant, or mortality from 8.5% per year to 3.3% per year. Adverse effects from interferon alfa such as fatigue, depression, and bone marrow suppression are common. HBV nucleos(t)ide analogues, such as entecavir or tenofovir, are ineffective against HDV. Phase 3 randomized clinical trials of bulevirtide, which blocks entry of HDV into hepatocytes, and lonafarnib, which interferes with HDV assembly, showed that compared with placebo or observation, these therapies attained virological and biochemical response in up to 56% of patients after 96 weeks of bulevirtide monotherapy and 19% after 48 weeks of lonafarnib, ritonavir, and pegylated interferon alfa treatment. Conclusions and Relevance: HDV infection affects approximately 12 million to 72 million people worldwide and is associated with more rapid progression to cirrhosis and liver failure and higher rates of hepatocellular carcinoma than infection with HBV alone. Bulevirtide was recently approved for HDV in Europe, whereas pegylated interferon alfa is the only treatment available in most countries.