In vitro studies identify a low replication phenotype for hepatitis B virus genotype H generally associated with occult HBV and less severe liver disease

Viral Hepatitis: Host Immune Interaction, Pathogenesis and New Therapeutic Strategies

Viral hepatitis is a major cause of liver illness worldwide. Despite advances in the understanding of these infections, the pathogenesis of hepatitis remains a complex process driven by intricate interactions between hepatitis viruses and host cells at the molecular level. This paper will examine in detail the dynamics of these host-pathogen interactions, highlighting the key mechanisms that regulate virus entry into the hepatocyte, their replication, evasion of immune responses, and induction of hepatocellular damage. The unique strategies employed by different hepatitis viruses, such as hepatitis B, C, D, and E viruses, to exploit metabolic and cell signaling pathways to their advantage will be discussed. At the same time, the innate and adaptive immune responses put in place by the host to counter viral infection will be analyzed. Special attention will be paid to genetic, epigenetic, and environmental factors that modulate individual susceptibility to different forms of viral hepatitis. In addition, this work will highlight the latest findings on the mechanisms of viral persistence leading to the chronic hepatitis state and the potential implications for the development of new therapeutic strategies. Fully understanding the complex host-pathogen interactions in viral hepatitis is crucial to identifying new therapeutic targets, developing more effective approaches for treatment, and shedding light on the mechanisms underlying progression to more advanced stages of liver damage.

Occult hepatitis B virus infection and current perspectives on global WHO 2030 eradication

The current World Health Organization (WHO) Hepatitis Elimination Strategy suffers from lack of a target for diagnosing or expunging occult HBV infection. A sizable segment of the global population has an undetected HBV infection, particularly the high-risk populations and those residing in countries like India with intermediate endemicity. There is growing proof that people with hidden HBV infection can infect others, and that these infections are linked to serious chronic hepatic complications, especially hepatocellular carcinoma. Given the current diagnostic infrastructure in low-resource settings, the WHO 2030 objective of obliterating hepatitis B appears to be undeniably challenging to accomplish. Given the molecular basis of occult HBV infection strongly linked to intrahepatic persistence, patients may inexplicably harbour HBV genomes for a prolonged duration without displaying any pronounced clinical or biochemical signs of liver disease, and present histological signs of moderate degree necro-inflammation, diffuse fibrosis, and hence the international strategy to eradicate viral hepatitis warrants inclusion of occult HBV infection.

The in vitro replication phenotype of hepatitis B virus (HBV) splice variants Sp3 and Sp9 and their impact on wild-type HBV replication

Prior to nuclear export, the hepatitis B virus (HBV) pregenomic RNA may be spliced by the host cell spliceosome to form shorter RNA sequences known as splice variants. Due to deletions in the open reading frames, splice variants may encode novel fusion proteins. Although not essential for HBV replication, the role of splice variants and their novel fusion proteins largely remains unknown. Some splice variants and their encoded novel fusion proteins have been shown to impair or promote wild-type HBV replication in vitro, and although splice variants Sp3 and Sp9 are two of the most common splice variants identified to date, their in vitro replication phenotype and their impact on wild-type HBV replication are unclear. Here, we utilize greater than genome-length Sp3 and Sp9 constructs to investigate their replication phenotype in vitro, and their impact on wild-type HBV replication. We show that Sp3 and Sp9 were incapable of autonomous replication, which was rescued by providing the polymerase and core proteins in trans. Furthermore, we showed that Sp3 had no impact on wild-type HBV replication, whereas Sp9 strongly reduced wild-type HBV replication in co-transfection experiments. Knocking out Sp9 novel precore-surface and core-surface fusion protein partially restored replication, suggesting that these proteins contributed to suppression of wild-type HBV replication, providing further insights into factors regulating HBV replication in vitro.

IMPORTANCE

The role of hepatitis B virus (HBV) splice variants in HBV replication and pathogenesis currently remains largely unknown. However, HBV splice variants have been associated with the development of hepatocellular carcinoma, suggesting a role in HBV pathogenesis. Several in vitro co-transfection studies have shown that different splice variants have varying impacts on wild-type HBV replication, perhaps contributing to viral persistence. Furthermore, all splice variants are predicted to produce novel fusion proteins. Sp1 hepatitis B splice protein contributes to liver disease progression and apoptosis; however, the function of other HBV splice variant novel fusion proteins remains largely unknown. We show that Sp9 markedly impairs HBV replication in a cell culture co-transfection model, mediated by expression of Sp9 novel fusion proteins. In contrast, Sp3 had no effect on wild-type HBV replication. Together, these studies provide further insights into viral factors contributing to regulation of HBV replication.

Pre- and Post-Transcriptional Control of HBV Gene Expression: The Road Traveled towards the New Paradigm of HBx, Its Isoforms, and Their Diverse Functions

Hepatitis B virus (HBV) is an enveloped DNA human virus belonging to the Hepadnaviridae family. Perhaps its main distinguishable characteristic is the replication of its genome through a reverse transcription process. The HBV circular genome encodes only four overlapping reading frames, encoding for the main canonical proteins named core, P, surface, and X (or HBx protein). However, pre- and post-transcriptional gene regulation diversifies the full HBV proteome into diverse isoform proteins. In line with this, hepatitis B virus X protein (HBx) is a viral multifunctional and regulatory protein of 16.5 kDa, whose canonical reading frame presents two phylogenetically conserved internal in-frame translational initiation codons, and which results as well in the expression of two divergent N-terminal smaller isoforms of 8.6 and 5.8 kDa, during translation. The canonical HBx, as well as the smaller isoform proteins, displays different roles during viral replication and subcellular localizations. In this article, we reviewed the different mechanisms of pre- and post-transcriptional regulation of protein expression that take place during viral replication. We also investigated all the past and recent evidence about HBV HBx gene regulation and its divergent N-terminal isoform proteins. Evidence has been collected for over 30 years. The accumulated evidence simply strengthens the concept of a new paradigm of the canonical HBx, and its smaller divergent N-terminal isoform proteins, not only during viral replication, but also throughout cell pathogenesis.

Analysis of the complete genome of HBV genotypes F and H found in Brazil and Mexico using the next generation sequencing method

INTRODUCTION AND OBJECTIVES

Hepatitis B Virus is classified into ten different genotypes (A- J). Genotypes F and H cluster apart from others in phylogenetic trees and is particularly frequent in the Americas. The aim of this study was to sequence complete genomes of samples of HBV genotypes F and H from Brazil and Mexico using next generation sequencing (NGS) and to study relevant characteristics for the disease associated with this virus.

MATERIALS AND METHODS

Ninety plasma samples with detectable HBV DNA belonging to the F (n=59) and H (n=31) genotypes were submitted to amplification of the complete HBV genome by three different methologies. Data analysis was developed using bioinformatics tools for quality assurance and comprehensive coverage of the genome. Sequences were aligned with reference sequences for subgenotyping and detecting variants in relevant positions. A phylogenetical tree was constructed using Bayesian methods.

RESULTS

HBV genome of 31 samples were amplified and 18 of them were sequenced (HBV/F=16 and HBV/H=2). One genotype F sample was co-infected with the F1b and F3 subgenotypes, while the other samples were all F2a subgenotype. Two genotype H samples clustered with other Mexican sequences. The main variants observed were found in preS and S genes (7/18) and mutations in the precore/core region (11/18).

CONCLUSIONS

A NGS methodology was applied to F and H genotypes samples from Mexico and Brazil to fully characterize their sequences. This methodology will be relevant for clinical and epidemiological studies of hepatitis B in Latin America.

Influence of genetic and environmental risk factors in the development of hepatocellular carcinoma in Mexico

The latest studies on the epidemiology of diverse types of cancers have located in the scene the relevance of liver tumors, particularly hepatocellular carcinoma (HCC). HCC is a life-threatening malignancy triggered by chronic exposure to hepatitis B and C viruses, excessive alcohol intake, hepatic lipid droplet accumulation, and aflatoxins that lead to persistent liver damage. The occurrence of such etiological risk factors deeply marks the variability in the incidence of HCC worldwide reflected by geography, ethnicity, age, and lifestyle factors influenced by cultural aspects. New perspectives on the primary risk factors and their potential gene-environment interactions (GxE) have been well-addressed in some cancers; however, it continues to be a partially characterized issue in liver malignancies. In this review, the epidemiology of the risk factors for HCC are described enhancing the GxE interactions identified in Mexico, which could mark the risk of this liver malignancy among the population and the measures needed to revert them. Updated healthcare policies focusing on preventive care should be tailored based on the genetic and environmental risk factors, which may influence the effect of the etiological agents of HCC. Robust regional investigations related to epidemiological, clinical, and basic studies are warranted to understand this health problem complying with the rules of ethnic, genetic, environmental, and social diversity.

Distribution of hepatitis B virus genotypes and subgenotypes: A meta-analysis

Hepatitis B virus (HBV) genotypes and subgenotypes have distinct geographical distributions and influence a number of clinical disease features and responses to treatment. There are many reports on the distribution of HBV genotypes, but great differences are present between studies. What's more, a meta-analysis of HBV genotype- and subgenotype-distribution by country is lacking.A comprehensive literature search was performed in PubMed and a systematic search of full-length HBV sequences and S gene sequences was conducted in the GenBank database. HBV genotypes were checked and subgenotypes were determined by phylogenetic comparison of full-length HBV sequences or S gene sequences. STATA 12.0 was used for the analysis for countries with multiple datasets. BEAST 2.5.2 was used for Bayesian phylogenetic analysis to infer the evolutionary time scales of HBV.This study includes 309 datasets from 110 countries, including 188 relevant studies, 58 full-length gene datasets, and 63 S gene datasets. The meta-analysis was performed on 274 datasets from 75 countries. The distribution of genotypes is more detailed than those described by previous studies. While the overall genotype distribution is similar to that reported in previous studies, some notable aspects were different. The main genotypes present in south-eastern Africa, North Africa, and West Africa are genotypes A, D, and E, respectively. Genotypes G and H are mainly distributed in Mexico. Genotype F is mainly distributed in central and South America, but genotypes A and D are also common in Brazil, Cuba, and Haiti.This study provides a more accurate description of the distribution of HBV genotypes and subgenotypes in different countries and suggests that the differences in genotype distribution may be related to ethnicity and human migration.

Infection courses, virological features and IFN-α responses of HBV genotypes in cell culture and animal models

BACKGROUND & AIMS

HBV consists of 9 major genotypes (A to I), 1 minor strain (designated J) and multiple subtypes, which may be associated with different clinical characteristics. As only cell lines expressing genotype D3 have been established, herein, we aimed to establish stable cell lines producing high-titer cell culture-generated HBV (HBVcc) of different genotypes and to explore their infectivity, virological features and responses to treatment.

METHODS

Stable cell lines producing high titers of HBV genotype A2, B2, C1, E, F1b and H were generated by transfecting plasmids containing a replication-competent 1.3x length HBV genome and an antibiotic marker into HepG2 cells that can support HBV replication. Clones with the highest levels of HBV DNA and/or HBeAg were selected and expanded for large-scale purification of HBVcc. HBVcc of different genotypes were tested in cells and a humanized chimeric mouse model.

RESULTS

HBVcc genotypes were infectious in mouse-passaged primary human hepatocytes (PXB cells) and responded differently to human interferon (IFN)-α with variable kinetics of reduction in HBV DNA, HBeAg and HBsAg. HBVcc of all genotypes were infectious in humanized chimeric mice but with variable kinetics of viremia and viral antigen production. Treatment of infected mice with human IFN-α resulted in modest and variable reductions of viremia and viral antigenemia. HBVcc passaged in humanized chimeric mice (HBVmp) infected PXB cells much more efficiently than that of the original HBVcc viral stock.

CONCLUSIONS

Herein, we generated stable cell lines producing HBV of various genotypes that are infectious in vitro and in vivo. We observe genotype-associated variations in viral antigen production, infection kinetics and responses to human IFN-α treatment in these models.

LAY SUMMARY

Stable cell lines producing high-titer cell culture-generated hepatitis B virus (HBV) of various genotypes were established. HBV genotypes showed stable infectivity in both in vitro and in vivo models, which are valuable tools for antiviral development.

Biological Characterization of Hepatitis B virus Genotypes: Their Role in Viral Replication and Antigen Expression

Hepatitis B virus (HBV) inter-host evolution has resulted in genomic diversification reflected in the existence of nine genotypes (A-I) and numerous subgenotypes. There is growing evidence that genotypes influence HBV natural history, clinical outcomes, and treatment response. However, the biological characteristics underlying these differences have not yet been established. By transfecting HuH-7 cells with unit-length constructs of genotypes A2, B2, C1, D1, and F1b, we identified major differences in HBV replicative capacity and antigen expression across genotypes. Genotypes B2 and F1b showed a 2-fold increase in cccDNA levels compared to the other genotypes (p<0.005). Genotype A2 expressed the lowest pgRNA levels, with a 70-fold decrease in relation to the other genotypes (p<0.0001), while genotype B2 showed the lowest Precore RNA levels, with a 100-fold reduction compared to genotype A2 (p<0.0001). The highest intracellular HBV DNA levels were observed for genotype B2 and the lowest for genotypes A2 and C1 (p<0.0001). Regarding antigen expression, genotype F1b secreted the highest HBsAg levels and genotype D1 the lowest (p<0.0001), while genotypes A2 and B2 showed the highest intracellular HBsAg levels (p<0.0001). Interestingly, genotype C1 secreted the highest HBeAg levels, while genotype A2 showed the highest intracellular levels (p<0.0001). Finally, the analysis of the intra/extracellular antigen ratios revealed that most genotypes retained intracellularly 5-20% of the antigens, except the genotype A2 that retained 50% of the total expressed antigens. In conclusion, this study provides new insights into the biological characteristics of HBV genotypes, being the first study to comparatively analyze European (A and D) and Asian (B and C) genotypes with the Latin American (F) genotype. The differences in HBV replication and antigen expression might contribute to understand the differential role of genotypes in pathogenesis.

Canonical and Divergent N-Terminal HBx Isoform Proteins Unveiled: Characteristics and Roles during HBV Replication

Hepatitis B virus (HBV) X protein (HBx) is a viral regulatory and multifunctional protein. It is well-known that the canonical HBx reading frame bears two phylogenetically conserved internal in-frame translational initiation codons at Met2 and Met3, thus possibly generating divergent N-terminal smaller isoforms during translation. Here, we demonstrate that the three distinct HBx isoforms are generated from the ectopically expressed HBV HBx gene, named XF (full-length), XM (medium-length), and XS (short-length); they display different subcellular localizations when expressed individually in cultured hepatoma cells. Particularly, the smallest HBx isoform, XS, displayed a predominantly cytoplasmic localization. To study HBx proteins during viral replication, we performed site-directed mutagenesis to target the individual or combinatorial expression of the HBx isoforms within the HBV viral backbone (full viral genome). Our results indicate that of all HBx isoforms, only the smallest HBx isoform, XS, can restore WT levels of HBV replication, and bind to the viral mini chromosome, thereby establishing an active chromatin state, highlighting its crucial activities during HBV replication. Intriguingly, we found that sequences of HBV HBx genotype H are devoid of the conserved Met3 position, and therefore HBV genotype H infection is naturally silent for the expression of the HBx XS isoform. Finally, we found that the HBx XM (medium-length) isoform shares significant sequence similarity with the N-terminus domain of the COMMD8 protein, a member of the copper metabolism MURR1 domain-containing (COMMD) protein family. This novel finding might facilitate studies on the phylogenetic origin of the HBV X protein. The identification and functional characterization of its isoforms will shift the paradigm by changing the concept of HBx from being a unique, canonical, and multifunctional protein toward the occurrence of different HBx isoforms, carrying out different overlapping functions at different subcellular localizations during HBV genome replication. Significantly, our current work unveils new crucial HBV targets to study for potential antiviral research, and human virus pathogenesis.

Analysis of Hepatitis B Virus Haplotype Diversity Detects Striking Sequence Conservation Across Genotypes and Chronic Disease Phase

BACKGROUND AND AIMS

We conducted haplotype analysis of complete hepatitis B virus (HBV) genomes following deep sequencing from 368 patients across multiple phases of chronic hepatitis B (CHB) infection from four major genotypes (A-D), analyzing 4,110 haplotypes to identify viral variants associated with treatment outcome and disease progression.

APPROACH AND RESULTS

Between 18.2% and 41.8% of nucleotides and between 5.9% and 34.3% of amino acids were 100% conserved in all genotypes and phases examined, depending on the region analyzed. Hepatitis B e antigen (HBeAg) loss by week 192 was associated with different haplotype populations at baseline. Haplotype populations differed across the HBV genome and CHB history, this being most pronounced in the precore/core gene. Mean number of haplotypes (frequency) per patient was higher in immune-active, HBeAg-positive chronic hepatitis phase 2 (11.8) and HBeAg-negative chronic hepatitis phase 4 (16.2) compared to subjects in the "immune-tolerant," HBeAg-positive chronic infection phase 1 (4.3, P< 0.0001). Haplotype frequency was lowest in genotype B (6.2, P< 0.0001) compared to the other genotypes (A = 11.8, C = 11.8, D = 13.6). Haplotype genetic diversity increased over the course of CHB history, being lowest in phase 1, increasing in phase 2, and highest in phase 4 in all genotypes except genotype C. HBeAg loss by week 192 of tenofovir therapy was associated with different haplotype populations at baseline.

CONCLUSIONS

Despite a degree of HBV haplotype diversity and heterogeneity across the phases of CHB natural history, highly conserved sequences in key genes and regulatory regions were identified in multiple HBV genotypes that should be further investigated as targets for antiviral therapies and predictors of treatment response.

A PCR assay to quantify patterns of HBV transcription

Hepatitis B virus (HBV) is the prototype member of the family Hepadnaviridae and replicates via episomal copies of a covalently closed circular DNA (cccDNA) genome of approximately 3.2 kb. The chromatinization of this small viral genome, with overlapping open reading frames and regulatory elements, suggests an important role for epigenetic pathways to regulate HBV transcription. However, the host pathways that regulate HBV transcription and the temporal nature of promoter usage in infected cells are not well understood, in part due to the compact genome structure and overlapping open reading frames. To address this we developed a simple and cost-effective PCR assay to quantify the major viral RNAs and validated this technique using current state-of-art de novo HBV infection model systems. Our PCR method is three orders of magnitude more sensitive than Northern blot and requires relatively small amounts of starting material, making this an attractive tool for assessing HBV transcription.

Efficacy and safety of spleen aminopeptide oral lyophilized powder in ameliorating liver injury in infants and children with human cytomegalovirus infection: a single-center study in China

BACKGROUND

Liver injury is both very common in infants and children and associated with low immune function. This study aimed to investigate the effect of spleen aminopeptide oral lyophilized powder (SAOLP) on liver injury in infants and children with human cytomegalovirus (HCMV) infection.

METHODS

In this prospective observational study, 217 infants and children with both liver damage and HCMV infection who were admitted to the Department of Pediatric Gastroenterology, Children's Hospital of Nanjing Medical University between July 2018 and May 2020 were investigated. The median age of patients was 0.75 years (0.36-3.77 years), with 105 male and 112 female participants. All 217 patients received ursodeoxycholic acid (UDCA) and/or reduced glutathione (GDC) therapy. Of these 217 patients, 114 also received SAOLP. Liver function, cellular immunity levels, HCMV antibody titer, and HCMV-DNA load values were measured 1 day before treatment, and on the second and fourth week after treatment.

RESULTS

After 4 weeks, patients treated with SAOLP showed median levels of serum alanine aminotransferase (ALT), total bilirubin (TB), and direct bilirubin (DB) which were significantly lower than those seen in patients who did not receive it. In addition, the percentage of CD4+ cells was significantly higher in those treated with SAOLP in comparison to those treated with UDCA and/or GDC alone. The number of positive HCMV-immunoglobin M (IgM) patients was also sharply decreased in the group receiving SAOLP.

CONCLUSIONS

The addition of SAOLP to UDCA and/or GDC therapy may significantly relieve liver injury and reduce the jaundice index by enhancing immune function and anti-HCMV infection ability in infants and children.

Moving Fast Toward Hepatitis B Virus Elimination

Currently, there are two safe and effective therapeutic strategies for chronic hepatitis B treatment, namely, nucleoside analogs and interferon alpha (pegylated or non-pegylated). These treatments can control viral replication and improve survival; however, they do not eliminate the virus and therefore require long-term continued therapy. In addition, there are significant concerns about virus rebound on discontinuation of therapy and the development of fibrosis and hepatocellular carcinoma despite therapy. Therefore, the search for new, more effective, and safer antiviral agents that can cure hepatitis B virus (HBV) continues. Anti-HBV drug discovery and development is fundamentally impacted by our current understanding of HBV replication, disease physiopathology, and persistence of HBV covalently closed circular DNA (cccDNA). Several HBV replication targets are the basis for novel anti-HBV drug development strategies. Many of them are already in clinical trial phase 1 or 2, while others with promising results are still in preclinical stages. As research intensifies, potential HBV curative therapies and modalities in the pipeline are now on the horizon.

The evolution and clinical impact of hepatitis B virus genome diversity

The global burden of hepatitis B virus (HBV) is enormous, with 257 million persons chronically infected, resulting in more than 880,000 deaths per year worldwide. HBV exists as nine different genotypes, which differ in disease progression, natural history and response to therapy. HBV is an ancient virus, with the latest reports greatly expanding the host range of the Hepadnaviridae (to include fish and reptiles) and casting new light on the origins and evolution of this viral family. Although there is an effective preventive vaccine, there is no cure for chronic hepatitis B, largely owing to the persistence of a viral minichromosome that is not targeted by current therapies. HBV persistence is also facilitated through aberrant host immune responses, possibly due to the diverse intra-host viral populations that can respond to host-mounted and therapeutic selection pressures. This Review summarizes current knowledge on the influence of HBV diversity on disease progression and treatment response and the potential effect on new HBV therapies in the pipeline. The mechanisms by which HBV diversity can occur both within the individual host and at a population level are also discussed.

Association of TLR3 (rs3775291) and IL-10 (rs1800871) gene polymorphisms with susceptibility to Hepatitis B infection: A meta-analysis

TLR3 and IL-10 play a crucial role in antiviral defence. However, there is a controversy between TLR3 rs3775291 and IL-10 rs1800871 polymorphisms and the risk of hepatitis B virus (HBV) infection. The purpose of this study is to explore the relationship between the two single nucleotide mutations and the risk of HBV infection by meta-analysis. Medline, EMBASE, Web of Science, CNKI, China Wanfang database were searched for the case-control studies on the relationship between TLR3 rs3775291 and IL-10 rs1800871 polymorphism and susceptibility to HBV, updated to June 2020. The data were analysed by Stata 15.0 software. A total of 22 articles were included. The results showed that in the analysis of IL10 rs1800871 polymorphism and the risk of HBV infection, the pooled OR was 1.21 (95% CI 1.06-1.37), 1.28 (95% CI 1.04-1.56) and 1.20 (95% CI 1.06-1.37) and 1.40 (95% CI 1.07-1.83) in the allele model (C vs. T), dominant model (CC+CT vs. TT), recessive model (CC vs. CT+TT) and homozygous model (CC vs. TT), respectively. There was no statistical significance in the heterozygote model. A subgroup analysis of the Asian population showed similar results. The analysis of TLR3 rs3775291 polymorphism and the risk of HBV showed that in the allele model (T vs. C), the pooled OR was 1.30 (95% CI 1.05-1.61). Except for the recessive model, no significances were found in other genetic models. In conclusion, TLR3 rs3775291 and IL-10 rs1800871 polymorphisms are associated with the risk of HBV. Allele C and genotype CC at IL10 rs1800871 loci, as well as allele T and genotype TT at TLR rs3775291 loci, may increase susceptibility to Hepatitis B infection.

Residues Asn118 and Glu119 of hepatitis B virus X protein are critical for HBx-mediated inhibition of RIG-I-MAVS signaling

Hepatitis B virus (HBV) X protein (HBx) has been reported to counteract the innate immune responses through interfering with the pattern recognition receptors signaling activated by retinoic acid-inducible gene-I (RIG-I)-mitochondrial antiviral signaling protein (MAVS). Here, we showed that, compared to the HBx derived from genotype (gt) A, C and D, HBx of gtB exhibited more potent inhibitory activity on the RIG-I-MAVS-mediated interferon-β promoter activation. Functional analysis of the genotype-associated differences in amino acid sequence and the reciprocal mutation experiments in transient-transfection and infection cell models revealed that HBx with asparagine (N) and glutamic acid (E) at 118-119 positions inhibited RIG-I signaling and interacted with MAVS more efficiently than that with lysine (K) and aspartic acid (D). An impaired RIG-I-induced MAVS aggregation was observed in the presence of HBx-118N119E while MAVS-TRAF3 interaction was not affected. These results implicated that HBx gene heterogeneity may affect the innate immune responses to HBV infection.

Analysis of the in vitro replication phenotype of African hepatitis B virus (HBV) genotypes and subgenotypes present in Australia identifies marked differences in DNA and protein expression

Hepatitis B virus infection in Africa is characterised by distinct genotypes with observed differences in natural history and clinical outcomes. Replication-competent cDNA clones of African genotypes were generated from patient-derived sequences identified in African children with chronic hepatitis B infection living in Australia: A1 (wild-type and basal core promotor (BCP) mutant), D2, D6, and E, comparing the replication phenotype to an established D3 cDNA clone in a transient transfection cell culture model. All clones replicated efficiently although less than the European D3 reference clone, and demonstrated marked differences in replication capacity, highest for subgenotypes A1 and D2. The BCP mutation increased the replication levels of the A1 subgenotype compared to wild-type. Intracellular and secreted surface antigen and HBeAg protein expression also varied across genotypes. We observed differences in functional activity in the upstream regulatory region across the genotypes that may contribute to the replication and protein differences observed.

Long-term follow-up of a Japanese patient with hepatitis B virus genotype H and human immunodeficiency virus coinfection

Hepatitis B virus (HBV) genotypes affect the pathogenesis of disease progression during the course of HBV infection. In Japan, HBV genotype H is one of the rare HBV genotypes. We recovered HBV genotype H from a blood sample from a Japanese HIV-infected patient with acute exacerbation of chronic HBV infection. Due to the development of drugs for treating HBV and HIV, HBV genotype H and HIV coinfection has been well controlled by nucleos(t)ide analogs and highly active antiretroviral therapy, respectively, from 2002 to 2019. Further study is needed with regard to HBV genotype H and its pathogenesis.

Hepatitis B Virus Molecular Epidemiology, Host-Virus Interaction, Coinfection, and Laboratory Diagnosis in the MENA Region: An Update

Hepatitis B virus (HBV) is an enveloped partial double-stranded DNA virus that can cause acute and chronic hepatitis. According to the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC), 257 million people are living with HBV. Moreover, 20,900 acute hepatitis B cases were reported in 2016. Hepatitis B is highly prevalent in the African, Western Pacific, Eastern Mediterranean, South-East Asia, and European regions, respectively. Due to the high mutational rate of HBV and lack of reverse transcriptase proofreading activity, ten different genotypes with different geographical distributions have been identified. HBV pathogenesis and severity of infection depend on several host and viral factors, particularly, the genetic variability of both the host and virus. Although HBV infection is a global health concern, there is a lack of adequate studies and reports in the Middle East and North Africa (MENA) region. Here, we provide a review on HBV epidemiology, pathogenesis, host-pathogen interactions, coinfection with selected viruses, and laboratory diagnosis, focusing on studies conducted in the MENA region to determine the current situation of the HBV infection and outline the future study areas.