Different evolutionary dynamics of hepatitis B virus genotypes A and D, and hepatitis D virus genotypes 1 and 2 in an endemic area of Yakutia, Russia

Diagnostic Efficacy of Serological Antibody Detection Tests for Hepatitis Delta Virus: A Systematic Review and Meta-Analysis

Background and Aims Coinfection of hepatitis delta virus (HDV) with hepatitis B virus (HBV) causes the most severe form of viral hepatitis, and the global prevalence of HDV infection is underestimated. Although serological testing of anti-HDV antibodies is widely used in the diagnosis of HDV, its diagnostic efficacy remains unclear. This study aimed to evaluate the diagnostic efficacy of HDV serological tests, the results of which may assist in the diagnosis of HDV. Methods Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed. The PubMed, Web of Science and Cochrane Library databases were searched from the beginning to 31 May 2023. Study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. STATA SE was used for the meta-analysis of the sensitivity, specificity, positive likelihood ratio and negative likelihood ratio. Results Among a total of 1376 initially identified studies, only 12 articles met the final inclusion criteria. The pooled sensitivity and specificity were 1.00 (95% CI: 0.00-1.00) and 0.71 (95% CI: 0.50-0.78) for HDV total antibodies, 0.96 (95% CI: 0.83-0.99) and 0.98 (95% CI: 0.82-1.00) for anti-HDV IgM and 0.95 (95% CI: 0.86-0.98) and 0.96 (95% CI: 0.67-1.00) for anti-HDV IgG. The pooled sensitivity and specificity for HDV serological tests were 0.99 (95% CI: 0.96-1.00) and 0.90 (95% CI: 0.79-0.96). Conclusions This meta-analysis suggests that serological tests have high diagnostic performance in detecting antibodies against HDV, especially in HDV IgM and IgG. However, this conclusion is based on studies of a limited number and quality, and the development of new diagnostic tools with higher precision and reliability is still necessary.

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).

Phylogenetic and Phylodynamic Analysis of Delta Strains Circulating in Italy

The hepatitis delta virus (HDV) exhibits high genetic and evolutionary variability and is classified into eight genotypes (HDV-1 to -8). HDV-1 is the most widespread genotype worldwide and includes several subtypes. It predominates mainly in Europe, the Middle East, North America, and Northern Africa, and is associated with both severe and mild forms of liver disease. In this study, we performed phylogenetic and phylodynamic analyses of HDV strains circulating in Regione Lazio, Italy, to understand when these strains were introduced into the Lazio region and to define their genetic variability in Italy. Fifty HDV RNA positive patient samples were amplified using a nested RT-PCR approach targeting the HDV R0 region and sequenced. A phylogenetic tree of patient-derived sequences and reference sequences representing HDV-1 to -8 was constructed using the GTRGAMMA model in RAxML v8. The results indicated that HDV-1 was the predominant genotype with HDV-1d being the most frequently inferred subtype. HDV-1 sequences clustering with subtypes 1b and 1e were also identified. A phylodynamic analysis of HDV-1 sequences employing a Bayesian birth-death model inferred a clock rate of 3.04 × 10-4 substitutions per site per million years, with a 95% Highest Posterior Density (HPD) interval of 3.45 × 10-5 to 5.72 × 10-4. A Bayesian birth-death analysis with tree calibration based on a sample dating approach indicated multiple original sources of infection (from the late 1950s to late 1980s). Overall, these results suggest that HDV sequences from the native Italian and non-Italian patients analyzed in this study represent multiple lineages introduced across a wide period. A common ancestral origin should be excluded.

Post-Vaccination and Post-Infection Immunity to the Hepatitis B Virus and Circulation of Immune-Escape Variants in the Russian Federation 20 Years after the Start of Mass Vaccination

A neonatal vaccination against the Hepatitis B virus (HBV) infection was initiated in Russia 20 years ago, with catch-up immunization for adolescents and adults under the age of 60 years launched in 2006. Here, we have assessed the humoral immunity to HBV in different regions of Russia, as well as the infection frequency following 20 years of a nationwide vaccination campaign. We have also evaluated the role of immune-escape variants in continuing HBV circulation. A total of 36,149 healthy volunteers from nine regions spanning the Russian Federation from west to east were tested for HBV surface antigen (HBsAg), antibodies to HBV capsid protein (anti-HBc), and antibodies to HBsAg (anti-HBs). HBV sequences from 481 chronic Hepatitis B patients collected from 2018-2022 were analyzed for HBsAg immune-escape variants, compared with 205 sequences obtained prior to 2010. Overall, the HBsAg detection rate was 0.8%, with this level significantly exceeded only in one study region, the Republic of Dagestan (2.4%, p < 0.0001). Among the generation vaccinated at birth, the average HBsAg detection rate was below 0.3%, ranging from 0% to 0.7% depending on the region. The anti-HBc detection rate in subjects under 20 years was 7.4%, indicating ongoing HBV circulation. The overall proportion of participants under 20 years with vaccine-induced HBV immunity (anti-HBs positive, anti-HBc negative) was 41.7% but below 10% in the Tuva Republic and below 25% in the Sverdlovsk and Kaliningrad regions. The overall prevalence of immune-escape HBsAg variants was 25.2% in sequences obtained from 2018-2022, similar to the prevalence of 25.8% in sequences collected prior to 2010 (p > 0.05). The population dynamics of immune-escape variants predicted by Bayesian analysis have remained stable over the last 20 years, indicating the absence of vaccine-driven positive selection. In contrast, the wild-type HBV population size experienced a rapid decrease starting in the mid-1990s, following the introduction of mass immunization, but it subsequently began to recover, reaching pre-vaccination levels by 2020. Taken together, these data indicate that it is gaps in vaccination, and not virus evolution, that may be responsible for the continued virus circulation despite 20 years of mass vaccination.

Epidemiology, presentation, and therapeutic approaches for hepatitis D infections

INTRODUCTION

Chronic Hepatitis D virus (HDV) infection remains an important global public health problem, with a changing epidemiological landscape over the past decade along with widespread implementation of hepatitis B vaccination and human migration. The landscape of HDV treatments has been changing, with therapies that have been under development for the last decade now in late stage clinical trials. The anticipated availability of these new therapies will hopefully replace the current therapies which are minimally effective.

AREAS COVERED

This narrative review discusses the clinical course, screening and diagnosis, transmission risk factors, epidemiology, current and investigational therapies, and liver transplantation in HDV. Literature review was performed using PubMed and ClinicalTrials.gov and includes relevant articles from 1977 to 2022.

EXPERT OPINION

HDV infection is an important global public health issue with a true prevalence that is still unknown. The distribution of HDV infection has changed globally with the availability of HBV vaccination and patterns of human migration. As HDV infection is associated with accelerated disease courses and poor outcomes, the global community needs to agree upon a uniform HDV screening strategy to understand the truth of global prevalence such that new therapies can target appropriate individuals as they become available in the future.

A changing landscape: Tracking and analysis of the international HDV epidemiology 1999-2020

The international epidemiology of Hepatitis Delta Virus (HDV) is challenging to accurately estimate due to limited active surveillance for this rare infectious disease. Prior HDV epidemiological studies have relied on meta-analysis of aggregated and static datasets. These limitations restrict the capacity to actively detect low-level and/or geographically dispersed changes in the incidence of HDV diagnoses. This study was designed to provide a resource to track and analyze the international HDV epidemiology. Datasets analyzed collectively consisted of >700,000 HBV and >9,000 HDV reported cases ranging between 1999-2020. Datasets mined from government publications were identified for Argentina, Australia, Austria, Brazil, Bulgaria, Canada, Finland, Germany, Macao, Netherlands, New Zealand, Norway, Sweden, Taiwan, Thailand, United Kingdom, and United States. Time series analyses, including Mann-Kendall (MK) trend test, Bayesian Information Criterion (BIC), and hierarchal clustering, were performed to characterize trends in the HDV timelines. An aggregated prevalence of 2,560 HDV/HBV100,000 cases (95% CI 180-4940) or 2.56% HDV/HBV cases was identified, ranging from 0.26% in Canada to 20% in the United States. Structural breaks in the timeline of HDV incidence were identified in 2002, 2012, and 2017, with a significant increase occurring between 2013-2017. Significant increasing trends in reported HDV and HBV cases were observed in 47% and 24% of datasets, respectively. Analyses of the HDV incidence timeline identified four distinct temporal clusters, including Cluster I (Macao, Taiwan), Cluster II (Argentina, Brazil, Germany, Thailand), Cluster III (Bulgaria, Netherlands, New Zealand, United Kingdom, United States) and Cluster IV (Australia, Austria, Canada, Finland, Norway, Sweden). Tracking of HDV and HBV cases on an international scale is essential in defining the global impact of viral hepatitis. Significant disruptions of HDV and HBV epidemiology have been identified. Increased surveillance of HDV is warranted to further define the etiology of the recent breakpoints in the international HDV incidence.

Genetic Diversity and Possible Origins of the Hepatitis B Virus in Siberian Natives

A total of 381 hepatitis B virus (HBV) DNA sequences collected from nine groups of Siberian native populations were phylogenetically analyzed along with 179 HBV strains sampled in different urban populations of former western USSR republics and 50 strains from Central Asian republics and Mongolia. Different HBV subgenotypes predominated in various native Siberian populations. Subgenotype D1 was dominant in Altaian Kazakhs (100%), Tuvans (100%), and Teleuts (100%) of southern Siberia as well as in Dolgans and Nganasans (69%), who inhabit the polar Taimyr Peninsula. D2 was the most prevalent subgenotype in the combined group of Nenets, Komi, and Khants of the northern Yamalo-Nenets Autonomous Region (71%) and in Yakuts (36%) from northeastern Siberia. D3 was the main subgenotype in South Altaians (76%) and Buryats (40%) of southeastern Siberia, and in Chukchi (51%) of the Russian Far East. Subgenotype C2 was found in Taimyr (19%) and Chukchi (27%), while subgenotype A2 was common in Yakuts (33%). In contrast, D2 was dominant (56%) in urban populations of the former western USSR, and D1 (62%) in Central Asian republics and Mongolia. Statistical analysis demonstrated that the studied groups are epidemiologically isolated from each other and might have contracted HBV from different sources during the settlement of Siberia.

Phylogenetic analysis and prevalence of Delta hepatitis among HBsAg carriers in Afghanistan

The molecular profile of hepatitis Delta in Afghanistan remains unclear yet, therefore this study addresses the genotype of HDV among HBsAg carriers in Afghanistan. In total 234 HBsAg-positive sera were examined by chemiluminescent micro-particle immunoassay to detect Anti-HDV antibodies. Serologically positive samples were later approved via real-time PCR test and subsequently, a 731 bp segment of the HDV Delta antigen RNA region was sequenced in the Illumina platform. The isolates were genotyped via distance matrix/UPGMA analysis using Kimura 2-parameter by MEGA7 software package program. The HBV/HDV coinfection rate among HBsAg carriers in Afghanistan was 2.1%. Finally, 4 samples successfully amplified Hepatitis delta antigen (HDAg) which Later in phylogenetic analysis, all resided in branch genotype I and were stored at GenBank with accession numbers MK799645, MK799646, MK799647, MK799648. The HDV genotypic variations in the Afghan HBsAg carriers may be homogenous and HDV-1 may be the predominant genotype in Afghanistan.