Hepatitis delta virus: From infection to new therapeutic strategies

Quantitative Analysis of Hepatitis D Virus Using gRNA-Sensitive Semiconducting Polymer Dots

Hepatitis D virus (HDV) significantly influences the progression of liver diseases. Through clinical observations and database analyses, it has been established that patients coinfected with HDV and hepatitis B virus (HBV) experience accelerated progression toward cirrhosis, hepatocellular carcinoma (HCC), and liver failure compared to those infected solely with HBV. A higher viral load correlates with increased replicative activity, enhanced infectivity, and more severe disease manifestations. In this study, we use HDV gRNA-sensitive semiconducting polymer dots (Pdots) as the nanoprobes for the quantitative analysis of HDV copy number variations. The surface of the Pdots is engineered with a clamp design that includes a pair of reporter sequences, protection sequences, and capture sequences tailored to the conserved sequence length of the HDV genome. The capture sequence, comprising leading and trailing chains, specifically binds to the gRNA of the target virus. The protection sequence shields the Pdots from external interference, while the reporter sequence detects the presence of target gRNA through the degradation of fluorescent dye Cy5.5dt. We demonstrate the effectiveness of this assay in a stably transfected cell line derived from HepG2-HDV cells and its translational application in clinical samples from patients. Additionally, this nanobiosensor can accurately detect gRNA at femtomolar (fM) levels, a sensitivity unachievable by previously reported methods. This novel virus quantification system offers significant potential for clinical and virological applications, enhancing screening, early diagnosis, and personalized treatment strategies.

Current Treatment Regimens and Promising Molecular Therapies for Chronic Hepatobiliary Diseases

Chronic hepatobiliary damage progressively leads to fibrosis, which may evolve into cirrhosis and/or hepatocellular carcinoma. The fight against the increasing incidence of liver-related morbidity and mortality is challenged by a lack of clinically validated early-stage biomarkers and the limited availability of effective anti-fibrotic therapies. Current research is focused on uncovering the pathogenetic mechanisms that drive liver fibrosis. Drugs targeting molecular pathways involved in chronic hepatobiliary diseases, such as inflammation, hepatic stellate cell activation and proliferation, and extracellular matrix production, are being developed. Etiology-specific treatments, such as those for hepatitis B and C viruses, are already in clinical use, and efforts to develop new, targeted therapies for other chronic hepatobiliary diseases are ongoing. In this review, we highlight the major molecular changes occurring in patients affected by metabolic dysfunction-associated steatotic liver disease, viral hepatitis (Delta virus), and autoimmune chronic liver diseases (autoimmune hepatitis, primary biliary cholangitis, and primary sclerosing cholangitis). Further, we describe how this knowledge is linked to current molecular therapies as well as ongoing preclinical and clinical research on novel targeting strategies, including nucleic acid-, mesenchymal stromal/stem cell-, and extracellular vesicle-based options. Much clinical development is obviously still missing, but the plethora of promising potential treatment strategies in chronic hepatobiliary diseases holds promise for a future reversal of the current increase in morbidity and mortality in this group of patients.

Molecular Epidemiology of Hepatitis D Virus in the North-East Region of Romania

The hepatitis D virus (HDV) superinfection of individuals with chronic hepatitis B virus (HBV) infection causes severe liver damage and the poorest long-term prognosis among viral hepatitis. This is attributed to the unique pathogenic mechanisms of HDV characterized by a direct cytopathic effect on hepatocytes and a significant impairment of the host immune response. The HDV genotype largely influences the extent of the pathogenic mechanisms with consequences on disease progression towards cirrhosis, liver decompensation, or hepatocellular carcinoma. In this context, identifying the circulating HDV genotypes in European regions with high prevalence, such as Romania, is crucial for effectively managing the long-term liver health. Here, we report the first comprehensive HDV study in Romania that clinically characterizes 82 patients and performs HDV genotyping by combining the nested-PCR reaction with sequencing analysis in 49 samples with an HDV-RNA load higher than 5000 IU/mL. While all isolates in our study belong to the HDV-1 genotype, the phylogenetic analysis based on sequence data from GenBank reveals the presence of the following potential three groups: (i) Italy and France; (ii) Spain; and (iii) Turkey, Iran, Pakistan, and Germany. This broad clustering highlights the recent surge in migration to and from Western Europe and the Middle East. Equally important, no differences in viral markers, clinical and paraclinical parameters, or treatment options were observed between these identified clusters. Nevertheless, this study considerably advances the understanding of hepatitis D epidemiology and clinical aspects in Romania.

Comparison of Clinical Features of HBV and HDV Coinfection with HBV Monoinfection: A Study from the Developing World

Hepatitis B infection remains a significant global health concern, with hepatitis D co-infection observed in approximately 5% of the patients. Treatment options for hepatitis D are currently limited, with most therapies awaiting approval by the FDA. However, there is a lack of comprehensive data on the prevalence and clinical presentation of patients with hepatitis B and D coinfection, particularly in Pakistan. In this study, we aimed to compare demographic characteristics, clinical presentations, laboratory, and endoscopic parameters along with the different treatment options between patients with hepatitis B monoinfection and those with hepatitis B and D coinfection.

How to cite this article

Majid Z, Abrar G, Ahsam S, et al. Comparison of Clinical Features of HBV and HDV Coinfection with HBV Mono-Infection: A Study from the Developing World. Euroasian J Hepato-Gastroenterol 2024;14(2):151-155.

Understanding the Natural History of Chronic Hepatitis D: Proposal of a Model for Cost-Effectiveness Studies

BACKGROUND

As new therapeutic options become available, better understanding the potential impact of emerging therapies on clinical outcomes of hepatits D virus (HDV) is critical.

OBJECTIVE

The aim of this study was to develop a natural history model for patients with hepatitis D virus.

METHODS

We developed a model (decision tree followed by a Markov cohort model) in adults with chronic HDV infection to assess the natural history and impact of novel treatments on disease progression versus best supportive care (BSC). The model time horizon was over a lifetime (up to 100 years of age); state transitions and health states were defined by responder status. Patients in fibrosis stages 0 through 4 received treatment; decompensated patients were not treated. Response was defined as the combined response endpoint of achievement of HDV-RNA undetectability/≥2-log10 decline and alanine aminotransferase normalization; response rates of 50% and 75% were explored. Health events associated with advanced liver disease were modeled as the number of events per 10,000 patients. Scenario analyses of early treatment, alternate treatment response, and no fibrosis regression for treatment responders were also explored.

RESULTS

The model was able to reflect disease progression similarly to published natural history studies for patients with HBV/HDV infection. In a hypothetical cohort of patients reflecting a population enrolled in a recent clinical trial, fewer advanced liver disease events were observed with a novel HDV treatment versus BSC. Fewer liver-related deaths were observed under 50% and 75% response (900 and 1,358 fewer deaths, respectively, per 10,000 patients). Scenario analyses showed consistently fewer advanced liver disease events with HDV treatment compared with BSC, with greater reductions observed with earlier treatment.

CONCLUSION

This HDV disease progression model replicated findings from natural history studies. Furthermore, it found that a hypothetical HDV treatment results in better clinical outcomes for patients versus BSC, with greater benefit observed when starting treatment early. This validated natural history model for HBV/HDV infection can serve as a foundation for future clinical and economic analyses of novel HDV treatments that can support healthcare stakeholders in the management of patients with chronic HDV.

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.

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).

Prevalence and genotypes distribution of virus hepatitis B and hepatitis delta virus in chronic liver diseases in Kazakhstan

BACKGROUND

The geographical distribution of hepatitis B virus (HBV) and hepatitis D virus (HDV) genotypes is uneven and has its own clinical and organizational implications for health systems. Despite the introduction of vaccination and successful antiviral therapy the prevalence of chronic hepatitis B (with or without delta agent) increased over the past 5 years. This study aimed for the first time to investigate the molecular epidemiology of HBV and HDV in Kazakhstan.

METHODS

Total 834 chronic hepatitis B (with or without delta agent) patients were included to the study from November 2017 to June 2019. The material was collected from the regional hepatological сenters from 13 cities of Kazakhstan. Genotyping of HBV/HDV isolates was carried out using phylogenetic analysis of null-binary sequences of Kazakhstani isolates, in comparison with the reference sequences. Nucleotide sequence alignment was performed using the ClustalW algorithm, the "neighbor-joining" method was used for the construction of phylogenetic trees and subsequent analysis.

RESULTS

Overall 341 samples were PCR-positive and genotyped for HBV. Comparison and phylogenetic analysis of nucleotide sequences of HBV isolates showed that they were represented by genotypes HBV-D (95.9%), HBV-A (3.5%) and HBV-C (0.6%). At the same time, the identity of the nucleotide sequences of Kazakhstani isolates were: HBV-D (95-100%); HBV-A (97.2-100%) and HBV-C (99%). 256 samples were PCR positive and genotyped for HDV, all of them belonged to genotype 1.

CONCLUSION

This study describes for the first time the molecular epidemiology of HBV and HDV in Kazakhstan. The data obtained expand the knowledge of the global epidemiology of viruses; have potential implications for public health policy and for further clinical research on chronic hepatitis in Kazakhstan.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05095181 (registered on 27/10/2021).

Hepatitis delta virus infection prevalence, diagnosis and treatment in the Middle East: A scoping review

Hepatitis D virus (HDV) infection is a global public health concern, especially because of its unique existence in the presence of hepatitis B virus infection. HDV infection is estimated to affect 12 million people globally. Having a clearer understanding of its prevalence in all regions of the world is essential for helping direct preventive and early interventional treatment. This mini-review assessed the literature over the last 10 years to determine the prevalence, diagnostic means and treatment guidelines available for HDV in the Middle East. The search found limited data available in 21 articles, of which 18 were studies focused on Iran. Prevalence rates ranged dramatically among the countries, and none of the 12 countries included in the search had specific HDV guidelines. This review highlights the urgent need for more precise data for the Middle East region to help establish early diagnosis and treatment options for HDV.

Development of quantitative multiplex RT-qPCR one step assay for detection of hepatitis delta virus

Hepatitis Delta is a disease caused by exposure to hepatitis B (HBV) and hepatitis D (HDV) viruses, usually with a more severe clinical outcome when compared to an HBV monoinfection. To date, the real prevalence of HDV infection is underestimated and detection methods are poorly available, especially in more endemic regions. Therefore, a one-step RT-qPCR method for quantification of HDV-RNA was developed. Biological samples were selected between 2017 and 2023 from patients at the Ambulatório Especializado em Hepatites Virais of the Centro de Pesquisa em Medicina Tropical de Rondônia and Serviço de Assistência Especializada and underwent the test developed by this study and a second quantitative RT-qPCR assay. The slope of the initial quantitative assay was - 3.321 with an efficiency of 100.04% and amplification factor equal to 2. Analysis of the repeatability data revealed a Limit of Quantification of 5 copies/reaction and Limit of Detection (95%) of 2.83 copies per reaction. In the diagnostic sensitivity tests, there was an accuracy of 97.37% when compared to the reference test. This assay proved to be highly efficient and reproducible, making it a valuable tool to monitor hepatitis Delta patients and assess the risk of disease progression, as well as the effectiveness of treatment.

Low prevalence of hepatitis delta infection in Cuban HBsAg carriers: Prospect for elimination

Introduction

Infection with hepatitis delta virus (HDV) is one of the most severe hepatitis B virus (HBV) complications, with a more rapid progression to cirrhosis and an increased risk of hepatic decompensation and death. Data on HDV infection in Cuba are limited. The aims of our study were to determine the HDV prevalence in HBsAg carriers and to characterize the HDV strains circulating. The data were used to assess the possibility of HDV elimination in the Cuban HBV epidemiological setting.

Methods

Five hundred and two serum samples from the same number of HBsAg carriers collected in the period 2006-2019 from all over the country were tested for anti-HDV total antibodies. If positive, the samples were analyzed for HDV-RNA using Real-Time RT-PCR targeting the ribozyme and HD antigen domains followed by genotyping based on phylogenetic analysis.

Results

Two samples were anti-HDV positive [0.39% (95% CI 0.11-1.44)]. One of them was also HDV-RNA positive. Clinically, the patient with active HDV infection had compensated liver cirrhosis. Phylogenetic analysis showed that the virus belonged to genotype 1 and thus clustered with contemporary strains from North America, Europe, Middle East, and Asia.

Discussion

This is the first HDV study, including molecular detection and virus characterization, done after the introduction of the universal childhood anti-hepatitis B vaccination. The very low prevalence of HDV infection in HBsAg carriers combined with the high HBV vaccination coverage of all newborn children, of previously identified risk groups, and of the general population currently under 40 years of age suggests that HDV elimination is feasible in Cuba if the success in HBV control is maintained.

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.

Hepatitis Delta: Current Knowledge and Future Directions

Hepatitis delta virus (HDV) infection is caused by a unique circular RNA virus that relies on both the hepatitis B virus (HBV) antigen and human host polymerases for its transmission and replication. HDV infection can be acquired simultaneously with HBV as a coinfection or as a superinfection in patients already chronically infected with HBV. Chronic HDV is the most severe and progressive form of viral hepatitis-induced liver disease, accounting for significant morbidity and mortality worldwide. Despite the severity of disease and poor clinical outcomes, there are few therapeutic options for the treatment of HDV infection. This article discusses the epidemiology of HDV globally and in the United States, the diagnosis and clinical course of HDV infection, and the current and future therapeutic options for the management of HDV infection.