Epidemiology, pathogenesis and management of hepatitis D: update and challenges ahead

Long-term outcome of hepatitis delta in different regions world-wide: Results of the Hepatitis Delta International Network

BACKGROUND AND AIMS

Chronic hepatitis delta represents a major global health burden. Clinical features of hepatitis D virus (HDV) infection vary largely between different regions worldwide. Treatment approaches are dependent on the approval status of distinct drugs and financial resources.

METHODS

The Hepatitis Delta International Network (HDIN) registry involves researchers from all continents (Wranke, Liver International 2018). We here report long-term follow-up data of 648 hepatitis D patients recruited by 14 centres in 11 countries. Liver-related clinical endpoints were defined as hepatic decompensation (ascites, encephalopathy and variceal bleeding), liver transplantation, hepatocellular carcinoma or liver-related death.

RESULTS

Patient data were available from all continents but Africa: 22% from Eastern Mediterranean, 32% from Eastern Europe and Central Asia, 13% from Central and Southern Europe, 14% from South Asia (mainly Pakistan) and 19% from South America (mainly Brazil). The mean follow-up was 6.4 (.6-28) years. During follow-up, 195 patients (32%) developed a liver-related clinical event after 3.5 (±3.3) years. Liver cirrhosis at baseline and a detectable HDV RNA test during follow-up were associated with a worse clinical outcome in multivariate regression analysis while patients receiving interferon alfa-based therapies developed clinical endpoints less frequently. Patients from South Asia developed endpoints earlier and had the highest mortality.

CONCLUSIONS

The HDIN registry confirms the severity of hepatitis D and provides further evidence for HDV viraemia as a main risk factor for disease progression. Hepatitis D seems to take a particularly severe course in patients born in Pakistan. There is an urgent need to extend access to antiviral therapies and to provide appropriate education about HDV infection.

High Diagnostic Value of Transient Elastography for Advanced Fibrosis and Cirrhosis in Patients With Chronic Hepatitis Delta

BACKGROUND & AIMS

Liver biopsy remains the gold standard for fibrosis staging in patients with chronic hepatitis delta (CHD). Here, we comparatively evaluated the performance of transient elastography (TE) and biomarkers for the diagnosis of liver fibrosis in patients with CHD.

METHODS

A total of 230 HDV-infected RNA-positive patients from various centers who underwent liver biopsy and liver stiffness measurements (LSMs) using Fibroscan, within a period of 6 months maximum, were investigated retrospectively. Area under the receiver operating characteristic curve and Youden index were used to establish cutoff values of LSM. TE was compared with other noninvasive tests: aspartate aminotransferase to platelet ratio index, Fibrosis-4, and Delta-4 fibrosis scores.

RESULTS

Histologic fibrosis stage distribution was: 20.4% for F0-F1; 27.0% for F2; 18.7% for F3; and 33.9% for F4. TE demonstrated good diagnostic performance for detecting cirrhosis and advanced fibrosis with an Area under the receiver operating characteristic curve of 0.88 and 0.86, which were significantly higher than those obtained with the other noninvasive tests (P = .004 and P < .001). With a cutoff value of >12 kPa for cirrhosis, the sensitivity was 70.5%, specificity was 86.2%, positive predictive value was 72.4%, negative predictive value was 85.1%, and accuracy was 80.9%. Using 10.4 kPa as the cutoff value for F3, the sensitivity was 70.2%, specificity was 83.5%, positive predictive value was 82.5%, negative predictive value was 71.7%, and accuracy was 76.5%. In 89% of patients with LSM ≤6.2 kPa, liver biopsy disclosed only absent or minimal fibrosis.

CONCLUSION

TE demonstrated good diagnostic performance for advanced fibrosis and cirrhosis in patients with CHD. Advanced fibrosis is highly probable for LSM values ≥10 kPa. LSM values <6 kPa almost totally exclude significant fibrosis. Between 6 and 10 kPa, liver biopsy should be discussed.

Patient-reported outcomes in chronic hepatitis delta: An exploratory analysis of the phase III MYR301 trial of bulevirtide

BACKGROUND & AIMS

Once-daily treatment of chronic hepatitis delta (CHD) with bulevirtide is well tolerated and associated with significant reductions in HDV RNA in the blood and in biochemical liver disease activity. This study explored the effects of 48-week bulevirtide treatment on health-related quality of life (HRQoL) in patients with CHD.

METHODS

In an open-label, randomised, phase III trial, 150 patients with CHD and compensated liver disease were stratified by cirrhosis status and randomised 1:1:1 to no treatment (control), bulevirtide 2 mg/day, or bulevirtide 10 mg/day for 48 weeks. HRQoL was evaluated by the following patient-reported outcome instruments at baseline, 24 weeks, and 48 weeks: EQ-5D-3L, Hepatitis Quality of Life Questionnaire, and Fatigue Severity Scale.

RESULTS

Patient characteristics and HRQoL scores were balanced at baseline between the treatment (2 mg, n = 49; 10 mg, n = 50) and control (n = 51) groups. Patients receiving 2 mg bulevirtide reported significant improvements compared with controls on the Hepatitis Quality of Life Questionnaire domains of role physical, hepatitis-specific limitations, and hepatitis-specific health distress. Numerically higher scores for general health, hepatitis-specific limitations, and hepatitis-specific health distress domains were reported by patients with cirrhosis who received bulevirtide vs. controls. Fatigue Severity Scale scores remained stable across treatment groups throughout. At week 48, patients in the 2 mg group showed greater mean improvement from baseline in health status compared with controls on the EQ-5D-3L visual analogue scale.

CONCLUSION

Patient-reported outcomes indicate that 48-week treatment with bulevirtide monotherapy may improve aspects of HRQoL in patients with CHD.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier, NCT03852719.

IMPACT AND IMPLICATIONS

Bulevirtide 2 mg is the only approved treatment for patients with chronic hepatitis delta (CHD) in the EU. Patients with CHD have worse quality of life scores than those with chronic hepatitis B. Bulevirtide treatment for 48 weeks reduced HDV RNA and alanine aminotransferase levels and was well tolerated among patients with CHD. For the first time, this study shows that patients who received bulevirtide therapy for 48 weeks reported improvements in physical and hepatitis-related quality of life domains compared with those who did not receive therapy (control group).

Prevalence of Hepatitis D in People Living with HIV: A National Cross-Sectional Pilot Study

This study assesses the prevalence of hepatitis D virus (HDV) in people living with HIV (PLWHIV) in Greece. Given the compounding effects of HDV and hepatitis B (HBV) on liver disease progression, as well as the emergence of new therapeutic options such as bulevirtide, understanding regional disparities and the epidemiological impact of such co-infections is vital. A cross-sectional analysis was conducted utilizing 696 serum samples from PLWHIV attending five major university hospitals. The methodology included HDV antibody detection by ELISA and HDV RNA confirmation. Of the 30 HBsAg-positive samples analyzed, the study population was primarily male (93%), with a median age of 54 years. Participants had been on antiretroviral therapy for a median of 10 years, and the median CD4 count was 738 (539-1006) copies/mL. Additional serological findings revealed a 7% prevalence of hepatitis C virus (HCV) IgG antibodies and a 55% prevalence of hepatitis A virus (HAV) IgG antibodies. Seroreactivity for syphilis (RPR/VDRL/TPHA positive) was identified in 33% of the participants. The results indicated a low HDV prevalence, with only one individual (3%) testing positive for anti-HDV IgG antibodies and none for HDV RNA. This indicates a lower prevalence of HDV among PLWHIV with chronic HBV in Greece compared to global data.

Viral hepatitis-induced acute liver failure

Viral hepatitis-induced acute liver failure (ALF) is a preventable cause for liver-related mortality worldwide. Viruses are the most common cause for ALF in developing nations in contrast to the west, where acetaminophen is largely responsible. Viruses may be hepatotropic or affect the liver secondary to a systemic infection. In tropical countries, infections such as leptospirosis, scrub typhus and malaria can mimic the symptoms of ALF. Differentiating these ALF mimics is crucial because they require etiology-specific therapy. Treatment of viral hepatitis-induced ALF is two-pronged and directed towards providing supportive care to prevent organ failures and antiviral drugs for some viruses. Liver transplantation (LT) is an effective modality for patients deteriorating despite adequate supportive care. Early referral and correct identification of patients who require a transplant are important. Liver support devices and plasma exchange have evolved into "bridging modalities" for LT. Preventive strategies such as hand hygiene, use of clean and potable water and inclusion of vaccines against viral hepatitis in the national program are simple yet very effective methods focusing on the preventive aspect of this disease.

Epidemiology of hepatitis D virus infection in Europe: Is it vanishing?

Co-infection with hepatitis delta virus (HDV) is a challenging health care problem worldwide, estimated to occur in approximately 5%-10% of patients with chronic hepatitis B virus (HBV) infection. While HBV prevalence is decreasing globally, the prevalence of HDV infection is rising in some parts mainly due to injection drug use, sexual transmission and immigration from high endemicity areas. Eastern Europe and the Mediterranean are among the regions with high rates of endemicity for HDV and the immigration from high endemicity areas to Central and Western Europe has changed the HDV epidemiology. We aimed to review the prevalence of HDV infection in Europe. A paucity of publication appears in many European countries. Prevalence studies from some countries are old dated and some other countries did not report any prevalence studies. The studies are accumulated in few countries. Anti-HDV prevalence is high in Greenland, Norway, Romania, Sweden and Italy. Belgium, France, Germany, Spain, Switzerland, Turkey and United Kingdom reported decreasing prevalences. Among cirrhotic HBV patients, Germany, Italy and Turkey reported higher rates of HDV. The studies including centres across the Europe reported that HIV-HBV coinfected individuals have higher prevalence of HDV infection. The immigrants contribute the HDV infection burden in Greece, Italy, and Spain in an increasing rate. Previous studies revealed extremely high rates of HDV infection in Germany, Greece, Italy and Sweden. The studies report a remarkably high prevalence of hepatitis delta among HIV/HBV-coinfected individuals, individuals who inject drugs, immigrants and severe HBV infected patients across Europe. The HDV infection burden still appears to be significant. In the lack of an effective HDV therapy, prevention strategies and active screening of HBV/HDV appear as the most critical interventions for reducing the burden of liver disease related to HDV infection in Europe.

Modelling HDV kinetics under the entry inhibitor bulevirtide suggests the existence of two HDV-infected cell populations

Background & Aims

Bulevirtide (BLV) was approved for the treatment of compensated chronic hepatitis D virus (HDV) infection in Europe in 2020. However, research into the effects of the entry inhibitor BLV on HDV-host dynamics is in its infancy.

Methods

Eighteen patients with HDV under nucleos(t)ide analogue treatment for hepatitis B, with compensated cirrhosis and clinically significant portal hypertension, received BLV 2 mg/day. HDV RNA, alanine aminotransferase (ALT), and hepatitis B surface antigen (HBsAg) were measured at baseline, weeks 4, 8 and every 8 weeks thereafter. A mathematical model was developed to account for HDV, HBsAg and ALT dynamics during BLV treatment.

Results

Median baseline HDV RNA, HBsAg, and ALT were 4.9 log IU/ml [IQR: 4.4-5.8], 3.7 log IU/ml [IQR: 3.4-3.9] and 106 U/L [IQR: 81-142], respectively. During therapy, patients fit into four main HDV kinetic patterns: monophasic (n = 2), biphasic (n = 10), flat-partial response (n = 4), and non-responder (n = 2). ALT normalization was achieved in 14 (78%) patients at a median of 8 weeks (range: 4-16). HBsAg remained at pre-treatment levels. Assuming that BLV completely (∼100%) blocks HDV entry, modeling indicated that two HDV-infected cell populations exist: fast HDV clearing (median t1/2 = 13 days) and slow HDV clearing (median t1/2 = 44 days), where the slow HDV-clearing population consisted of ∼1% of total HDV-infected cells, which could explain why most patients exhibited a non-monophasic pattern of HDV decline. Moreover, modeling explained ALT normalization without a change in HBsAg based on a non-cytolytic loss of HDV from infected cells, resulting in HDV-free HBsAg-producing cells that release ALT upon death at a substantially lower rate compared to HDV-infected cells.

Conclusion

The entry inhibitor BLV provides a unique opportunity to understand HDV, HBsAg, ALT, and host dynamics.

Impact and implications

Mathematical modeling of hepatitis D virus (HDV) treatment with the entry inhibitor bulevirtide (BLV) provides a novel window into the dynamics of HDV RNA and alanine aminotransferase. Kinetic data from patients treated with BLV monotherapy can be explained by hepatocyte populations with different basal HDV clearance rates and non-cytolytic clearance of infected cells. While further studies are needed to test and refine the kinetic characterization described here, this study provides a new perspective on viral dynamics, which could inform evolving treatment strategies for HDV.

Immunological pathways in viral hepatitis-induced hepato-cellular carcinoma

Hepatocellular carcinoma (HCC) is a serious neoplastic disease with increasing incidence and mortality, accounting for 90% of all liver cancers. Hepatitis viruses are the major causative agents in the development of HCC. Hepatitis A virus (HAV) primarily causes acute infections, which is associated with HCC to a certain extent, as shown by clinicopathological studies. Chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infections lead to persistent liver inflammation and cirrhosis, disrupt multiple pathways associated with cellular apoptosis and proliferation, and are the most common viral precursors of HCC. Mutations in the HBV X protein (HBx) gene are closely associated with the incidence of HCC, while the expression of HCV core proteins contributes to hepatocellular lipid accumulation, thereby promoting tumorigenesis. In the clinical setting, hepatitis D virus (HDV) frequently co-infects with HBV, increasing the risk of chronic hepatitis. Hepatitis E virus (HEV) usually causes acute infections. However, chronic infections of HEV have been increasing recently, particularly in immuno-compromised patients and organ transplant recipients, which may increase the risk of progression to cirrhosis and the occurrence of HCC. Early detection, effective intervention and vaccination against these viruses may significantly reduce the incidence of liver cancer, while mechanistic insights into the interplay between hepatitis viruses and HCC may facilitate the development of more effective intervention strategies. This article provides a comprehensive overview of hepatitis viruses and reviews recent advances in research on aberrant hepatic immune responses and the pathogenesis of HCC due to viral infection.

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

Background and Aims

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

Methods

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

Results

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

Conclusion

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

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.

Prevalence and determinants of hepatitis delta virus infection among HIV/hepatitis B-coinfected adults in care in the United States

Hepatitis delta virus (HDV) infection increases the risk of liver complications compared to hepatitis B virus (HBV) alone, particularly among persons with human immunodeficiency virus (HIV). However, no studies have evaluated the prevalence or determinants of HDV infection among people with HIV/HBV in the US. We performed a cross-sectional study among adults with HIV/HBV coinfection receiving care at eight sites within the Center for AIDS Research Network of Integrated Clinical Systems (CNICS) between 1996 and 2019. Among patients with available serum/plasma specimens, we selected the first specimen on or after their initial HBV qualifying test. All samples were tested for HDV IgG antibody and HDV RNA. Multivariable log-binomial generalized linear models were used to estimate prevalence ratios (PRs) with 95% CIs of HDV IgG antibody-positivity associated with determinants of interest (age, injection drug use [IDU], high-risk sexual behaviour). Among 597 adults with HIV/HBV coinfection in CNICS and available serum/plasma samples (median age, 43 years; 89.9% male; 52.8% Black; 42.4% White), 24/597 (4.0%; 95% CI, 2.4%-5.6%) were HDV IgG antibody-positive, and 10/596 (1.7%; 95% CI, 0.6%-2.7%) had detectable HDV RNA. In multivariable analysis, IDU was associated with exposure to HDV infection (adjusted PR = 2.50; 95% CI, 1.09-5.74). In conclusion, among a sample of adults with HIV/HBV coinfection in care in the US, 4.0% were HDV IgG antibody-positive, among whom 41.7% had detectable HDV RNA. History of IDU was associated with exposure to HDV infection. These findings emphasize the importance of HDV testing among persons with HIV/HBV coinfection, especially those with a history of IDU.

Broad-spectrum activity of bulevirtide against clinical isolates of HDV and recombinant pan-genotypic combinations of HBV/HDV

Background & Aims

Bulevirtide (BLV) is a small lipopeptide agent that specifically binds to the sodium taurocholate cotransporting polypeptide (NTCP) bile salt transporter and HBV/HDV receptor on the surface of human hepatocytes and inhibits HDV and HBV entry. As a satellite virus of HBV, HDV virions are formed after assembly of HDV RNA with the HBV envelope proteins (HBsAg). Because both viruses exist as eight different genotypes, this creates a potential for high diversity in the HBV/HDV combinations. To investigate the sensitivity of various combinations of HBV/HDV genotypes to BLV, clinical and laboratory strains were assessed.

Methods

For the laboratory strains, the different envelopes from HBV genotypes A through H were combined with HDV genotypes 1-8 in cotransfection assays. Clinical plasma isolates were obtained from clinical studies and academic collaborations to maximise the diversity of HBV/HDV genotypes tested.

Results

The mean BLV EC50 against HDV laboratory strains ranged from 0.44 to 0.64 nM. Regardless of HBV and HDV genotypes, the clinical isolates showed similar sensitivities to BLV with mean values that ranged from 0.2 to 0.73 nM.

Conclusions

These data support the use of BLV in patients infected with any HBV/HDV genotypes.

Impact and implications

This study describes the potent activity of BLV against multiple laboratory strains spanning all HBV/HDV A-H/1-8 genotype combinations and the most diverse collection of HDV clinical samples tested to date, including HBV/HDV genotype combinations less frequently observed in the clinic. Overall, all isolates and laboratory strains displayed similar in vitro nanomolar sensitivity to BLV. This broad-spectrum antiviral activity of BLV has direct implications on potential simplified treatment for any patient infected with HDV, regardless of genotype, and supports the new 2023 EASL Clinical Practice Guidelines on HDV that recommend antiviral treatment for all patients with CHD.

What Is the Real Epidemiology of Hepatitis D Virus and Why so Many Mixed Messages?

The disease burden of HDV is poorly understood. Our review identified multiple reasons: (1) HDV infection rates are overestimated in the general population due to limited sample sizes, sampling high-risk populations, and significant regional variations, (2) estimates are based on chronic HBV populations, but HBV burden itself is uncertain, (3) there is a lack of testing in at-risk populations, (4) prevalence testing is based on HDV antibody testing and not HDV RNA, which distinguishes between active infection versus prior exposure, (5) older studies used less reliable testing and (6) HBV vaccination programs have affected HDV prevalence, but is often not accounted for.

No virologic resistance to bulevirtide monotherapy detected in patients through 24 weeks treatment in phase II and III clinical trials for chronic hepatitis delta

BACKGROUND & AIMS

Bulevirtide (BLV) is a HDV/HBV entry inhibitor that is associated with virologic response (responders, HDV-RNA undetectable or ≥2 log10 IU/ml decrease from baseline) in >50% of patients after a 24-week treatment. However, some patients only achieve a <1 log10 IU/ml decline in HDV-RNA after the 24-week treatment (non-responders). Here, we report a viral resistance analysis in participants receiving BLV monotherapy who were non-responders or experienced virologic breakthrough (VB, i.e., two consecutive increases in HDV-RNA of ≥1 log10 IU/ml from nadir or two consecutive HDV-RNA detectable results if previously undetectable) from the phase II MYR202 and phase III MYR301 study.

METHODS

Deep-sequencing of the BLV-corresponding region in HBV PreS1 and of the HDV HDAg gene, as well as in vitro phenotypic testing, were performed for the participant with VB (n = 1) and non-responders (n = 20) at baseline (BL) and Week 24 (WK24).

RESULTS

No amino acid exchanges associated with reduced susceptibility to BLV within the BLV-corresponding region or within HDAg were identified in isolates from any of the 21 participants at BL or at WK24. Although variants (HBV n = 1; HDV n = 13) were detected at BL in some non-responders or in the participant with VB, none were associated with reduced sensitivity to BLV in vitro. Furthermore, the same variant was detected in virologic responders. A comprehensive phenotypic analysis demonstrated that the BLV EC50 values from 116 BL samples were similar across non-responders, partial responders (HDV RNA decline ≥1 but <2 log10 IU/ml), and responders regardless of the presence of HBV and/or HDV polymorphisms.

CONCLUSIONS

No amino acid substitutions associated with reduced sensitivity to BLV monotherapy were detected at BL or WK24 in non-responders or the participant with VB after 24-week BLV treatment.

IMPACT AND IMPLICATIONS

This is the first study investigating the development of resistance in patients treated with BLV. Excluding resistance to BLV as an explanation for an insufficient decrease in HDV-RNA levels during BLV therapy is an important finding for patients, clinicians, and researchers. It demonstrates that BLV has a high barrier to resistance, indicating it is safe and suitable for long-term treatment, although long-term surveillance for resistance should be performed. Our results hint at other still unknown mechanisms as an explanation for the persistence of serum HDV-RNA during inhibition of viral entry.

CLINICAL TRIAL NUMBERS

NCT03546621 and NCT03852719.

Diagnosis and Management of Hepatitis Delta Virus Infection

Hepatitis D virus (HDV) depends on hepatitis B virus (HBV) to enter and exit hepatocytes and to replicate. Despite this dependency, HDV can cause severe liver disease. HDV accelerates liver fibrosis, increases the risk of hepatocellular carcinoma, and hastens hepatic decompensation compared to chronic HBV monoinfection. The Chronic Liver Disease Foundation (CLDF) formed an expert panel to publish updated guidelines on the testing, diagnosis, and management of hepatitis delta virus. The panel group performed network data review on the transmission, epidemiology, natural history, and disease sequelae of acute and chronic HDV infection. Based on current available evidence, we provide recommendations for screening, testing, diagnosis, and treatment of hepatitis D infection and review upcoming novel agents that may expand treatment options. The CLDF recommends universal HDV screening for all patients who are Hepatitis B surface antigen-positive. Initial screening should be with an assay to detect antibodies generated against HDV (anti-HDV). Patients who are positive for anti-HDV IgG antibodies should then undergo quantitative HDV RNA testing. We also provide an algorithm that describes CLDF recommendations on the screening, diagnosis, testing, and initial management of Hepatitis D infection.

Hepatitis Delta Infection: A Clinical Review

First discovered over 40 years ago, the hepatitis delta virus (HDV) is a unique RNA virus, requiring hepatitis B virus (HBV) antigens for its assembly, replication, and transmission. HBV and HDV can be acquired at the same time (coinfection) or HDV infection can occur in persons with chronic HBV (superinfection). Screening guidelines for HDV are inconsistent. While some guidelines recommend universal screening for all people with HBV, others recommend risk-based screening. Estimates of the global HDV prevalence range from 4.5 to 14.6% among persons with HBV; thus, there may be up to 72 million individuals with HDV worldwide. HDV is the most severe form of viral hepatitis. Compared to HBV monoinfection, HDV coinfection increases the risk of cirrhosis, hepatocellular carcinoma, hepatic decompensation, mortality, and necessity for liver transplant. Despite the severity of HDV, there are few treatment options. Pegylated interferon (off-label use) has long been the only available treatment, although bulevirtide is conditionally approved in some European countries. There are many potential treatments in development, but as yet, there are few effective and safe therapies for HDV infection. In conclusion, given the severity of HDV disease and the paucity of treatments, there is a great unmet need for HDV therapies.

The Changing Epidemiology of Viral Hepatitis in a Post-Soviet Country-The Case of Kyrgyzstan

Historically, viral hepatitis has been a considerable public health problem in Central Asian countries, which may have worsened after the dissolution of the Soviet Union. However, up-to-date seroepidemiological studies are lacking. The aim of the present study was, therefore, to provide current estimates of the seroprevalence of viral hepatitis in Kyrgyzstan, one of the economically least developed countries in the region. We conducted a population-based cross-sectional study in 2018 in the capital of Kyrgyzstan, Bishkek (n = 1075). Participants, children and adults, were recruited from an outpatient clinic. The data were collected during face-to-face interviews. A blood sample (6 mL) was collected from each participant and tested with ELISA for the presence of serological markers for five viral hepatitides (A, B, C, D, and E). Post-stratification weighing was performed to obtain nationally representative findings. The overwhelming majority of the study participants were positive for anti-HAV (estimated seroprevalence, 75.3%; 95% confidence interval, 72.5-77.9%). The weighted seroprevalence estimates of HBsAg, anti-HCV, and anti-HDV were 2.2% (1.5-3.3%), 3.8% (2.8-5.1%), and 0.40% (0.15-1.01%), respectively. Anti-HEV seropositivity was 3.3% (2.4-4.5%). Of the 33 HBsAg-positive participants, five (15%) were anti-HDV-positive. Our study confirms that Kyrgyzstan remains a highly endemic country for hepatitis virus A and C infections. However, seroprevalences of HBV and HDV were lower than previously reported, and based on these data, the country could potentially be reclassified from high to (lower) intermediate endemicity. The observed anti-HEV seroprevalence resembles the low endemicity pattern characteristic of high-income countries.

A Phase 3, Randomized Trial of Bulevirtide in Chronic Hepatitis D

BACKGROUND

Coinfection with hepatitis D virus (HDV) accelerates the progression of liver disease associated with chronic hepatitis B. Bulevirtide inhibits the entry of HDV into hepatocytes.

METHODS

In this ongoing phase 3 trial, patients with chronic hepatitis D, with or without compensated cirrhosis, were randomly assigned, in a 1:1:1 ratio, to receive bulevirtide subcutaneously at 2 mg per day (2-mg group) or 10 mg per day (10-mg group) for 144 weeks or to receive no treatment for 48 weeks followed by bulevirtide subcutaneously at 10 mg per day for 96 weeks (control group). Patients will complete 96 weeks of additional follow-up after the end of treatment. The primary end point was a combined response at week 48 of an undetectable HDV RNA level, or a level that decreased by at least 2 log10 IU per milliliter from baseline, and normalization of the alanine aminotransferase (ALT) level. The key secondary end point was an undetectable HDV RNA level at week 48, in a comparison between the 2-mg group and the 10-mg group.

RESULTS

A total of 49 patients were assigned to the 2-mg group, 50 to the 10-mg group, and 51 to the control group. A primary end-point response occurred in 45% of patients in the 2-mg group, 48% in the 10-mg group, and 2% in the control group (P<0.001 for the comparison of each dose group with the control group). The HDV RNA level at week 48 was undetectable in 12% of patients in the 2-mg group and in 20% in the 10-mg group (P = 0.41). The ALT level normalized in 12% of patients in the control group, 51% in the 2-mg group (difference from control, 39 percentage points [95% confidence interval {CI}, 20 to 56]), and 56% in the 10-mg group (difference from control, 44 percentage points [95% CI, 26 to 60]). Loss of hepatitis B virus surface antigen (HBsAg) or an HBsAg level that decreased by at least 1 log10 IU per milliliter did not occur in the bulevirtide groups by week 48. Headache, pruritus, fatigue, eosinophilia, injection-site reactions, upper abdominal pain, arthralgia, and asthenia were more common in the 2-mg and 10-mg groups combined than in the control group. No treatment-related serious adverse events occurred. Dose-dependent increases in bile acid levels were noted in the 2-mg and 10-mg groups.

CONCLUSIONS

After 48 weeks of bulevirtide treatment, HDV RNA and ALT levels were reduced in patients with chronic hepatitis D. (Funded by Gilead Sciences; MYR 301 ClinicalTrials.gov number, NCT03852719.).

Systemic Inflammatory Molecules Are Associated with Advanced Fibrosis in Patients from Brazil Infected with Hepatitis Delta Virus Genotype 3 (HDV-3)

BACKGROUND AND AIMS

Hepatitis Delta virus (HDV) genotype 3 is responsible for outbreaks of fulminant hepatitis in Northeastern South America. This study investigates if systemic inflammatory molecules are differentially expressed in patients with advanced fibrosis chronically infected with Hepatitis Delta virusgenotype 3(HDV-3).

METHODS

Sixty-one patients from the north of Brazil coinfected with hepatitis B virus (HBV)/HDV-3 were analyzed. HDV quantification and genotyping were performed by semi-nested real-time polymerase chain reaction (RT-PCR) and restriction fragment length polymorphism (RFLP) methodologies. Ninety-two systemic inflammatory molecules (SIMs) were measured by Proximity Extension Assay (PEA) technology. The Shapiro-Wilk, Student's t-test, Mann-Whitney tests, and logistic regression analysis were used when appropriate.

RESULTS

The median age was 41 years, and all patients were HBeAg negative. Advanced fibrosis or cirrhosis was diagnosed by histological staging in 17 patients, while 44 presented with minimal or no fibrosis. Advanced necroinflammatory activity correlated positively with serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Established non-invasive fibrosis scores (APRI, FIB-4, and AST/ALT ratio) revealed low sensitivities and positive predictive values (PPVs) with an AUROC maximum of 0.586. Among the 92 SIMs analyzed, MCP.4, CCL19, EN.RAGE, SCF, and IL18 showed a positive correlation with fibrosis stage. A combined score including CCL19 and MCP.4 revealed a sensitivity of 81% and an odds ratio of 2.202 for advanced fibrosis.

CONCLUSIONS

Standard non-invasive fibrosis scores showed poor performance in HDV-3 infection. We here suggest that the determination of CCL19 and MCP.4 may be used to identify patients with advanced fibrosis. Moreover, this study gives novel insights into the immunopathogenesis of HDV-3 infection.

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

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

Molecular recognition of bio-active triterpenoids from Swertia chirayita towards hepatitis Delta antigen: a mechanism through docking, dynamics simulation, Gibbs free energy landscape

Medicinal plants the underpinning of indigenous herbal serve, are the possible source of key compounds for the development of new drugs. Hepatitis D, one of the most widespread infectious diseases associated with global public health issues. Therefore, we aim to screen natural compounds to find out potent inhibitor towards hepatitis delta antigen. Through ADMET investigation, we have screened twenty phytochemicals for this study. Additionally, using molecular docking, these phytochemicals were docked with the HDV protease which signifies the phytochemicals beta-amyrin, chiratenol, episwertenol and swertanone have a significant capability to bind with hepatitis D virus protein. The docking study was further accompanied by analyzes RMSD, RMSF, Rg, SASA, Hbond number, and principal component analysis through 100 ns MD simulations. Based on our principal component analysis, beta-amyrin, chiratenol, episwertenol and swertanone phytochemicals can be a potential drug candidates for inhibition of hepatitis D. The above observation is also supported by our Gibbs free energy landscape study. The potential therapeutic characteristics of the phytochemicals against hepatitis D inhibition offer additional support for the in vitro and in vivo studies in future.

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.

Magnitude and genotype of hepatitis delta virus among chronic hepatitis B carriers with a spectrum of liver diseases in Ethiopia

INTRODUCTION AND OBJECTIVES

Chronic hepatitis D infection contributes substantially to the progression of chronic liver disease, especially in most low and middle-income countries, where hepatitis B virus-related chronic liver disease is endemic. Therefore, this study aimed to determine the magnitude and genotype of hepatitis delta virus (HDV) among patients with chronic hepatitis B (CHB)-related liver diseases in Ethiopia.

PATIENTS AND METHODS

In this cross-sectional study, 323 known HBsAg positive individuals comprising 220 patients with CHB-related liver diseases [121 advanced liver diseases (hepatocellular carcinoma /HCC/ and non-HCC) and 99 chronic hepatitis (CH)], and 103 symptomless blood donors (BD) were enrolled. An ELISA kit was employed to determine HDV infection, and quantitative real-time PCR was used to detect HDV RNA. In addition, a non-coding genomic RNA region was sequenced for genotyping and phylogenetic analysis.

RESULTS

Irrespective of the stage of liver disease, the overall magnitude of HDV was 7.7% (25/323). The frequency of anti-HDV increases with the severity of liver disease, 1.9%, 4%, 10%, and 21.3% among BD, CH, non-HCC, and HCC patients, respectively. HDV RNA has been detected in 1.54 %(5/323) cases with a mean viral load of 4,010,360 IU/ml. All isolates were found to be HDV genotype 1.

CONCLUSIONS

The magnitude of HDV infection increased with the severity of liver disease, indicating HDV infection is more common among patients with CHB-related liver diseases in Ethiopia.

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.

Hepatitis D virus: Improving virological knowledge to develop new treatments

Hepatitis delta virus (HDV), a satellite of hepatitis B virus (HBV), possesses the smallest viral genome known to infect animals. HDV needs HBV surface protein for secretion and entry into target liver cells. However, HBV is dispensable for HDV genome amplification, as it relies almost exclusively on cellular host factors for replication. HBV/HDV co-infections affect over 12 million people worldwide and constitute the most severe form of viral hepatitis. Co-infected individuals are at higher risk of developing liver cirrhosis and hepatocellular carcinoma compared to HBV mono-infected patients. Bulevirtide, an entry inhibitor, was conditionally approved in July 2020 in the European Union for adult patients with chronic hepatitis delta (CHD) and compensated liver disease. There are several drugs in development, including lonafarnib and interferon lambda, with different modes of action. In this review, we detail our current fundamental knowledge of HDV lifecycle and review antiviral treatments under development against this virus, outlining their respective mechanisms-of-action. Finally, we describe the antiviral effect these compounds are showing in ongoing clinical trials, discussing their promise and potential pitfalls for managing HDV infected patients.

Medical Advances in Hepatitis D Therapy: Molecular Targets

An approximate number of 250 million people worldwide are chronically infected with hepatitis B virus, making them susceptible to a coinfection with hepatitis D virus. The superinfection causes the most severe form of a viral hepatitis and thus drastically worsens the course of the disease. Until recently, the only available therapy consisted of interferon-α, only eligible for a minority of patients. In July 2020, the EMA granted Hepcludex conditional marketing authorization throughout the European Union. This first-in-class entry inhibitor offers the promise to prevent the spread in order to gain control and eventually participate in curing hepatitis B and D. Hepcludex is an example of how understanding the viral lifecycle can give rise to new therapy options. Sodium taurocholate co-transporting polypeptide, the virus receptor and the target of Hepcludex, and other targets of hepatitis D therapy currently researched are reviewed in this work. Farnesyltransferase inhibitors such as Lonafarnib, targeting another essential molecule in the HDV life cycle, represent a promising target for hepatitis D therapy. Farnesyltransferase attaches a farnesyl (isoprenyl) group to proteins carrying a C-terminal Ca1a2X (C: cysteine, a: aliphatic amino acid, X: C-terminal amino acid) motif like the large hepatitis D virus antigen. This modification enables the interaction of the HBV/HDV particle and the virus envelope proteins. Lonafarnib, which prevents this envelopment, has been tested in clinical trials. Targeting the lifecycle of the hepatitis B virus needs to be considered in hepatitis D therapy in order to cure a patient from both coexisting infections. Nucleic acid polymers target the hepatitis B lifecycle in a manner that is not yet understood. Understanding the possible targets of the hepatitis D virus therapy is inevitable for the improvement and development of a sufficient therapy that HDV patients are desperately in need of.

HBsAg isoform dynamics during NAP-based therapy of HBeAg-negative chronic HBV and HBV/HDV infection

Nucleic acid polymers block the assembly of hepatitis B virus (HBV) subviral particles, effectively preventing hepatitis B surface antigen (HBsAg) replenishment in the circulation. Nucleic acid polymer (NAP)-based combination therapy of HBV infection or HBV/hepatitis D virus (HDV) co-infection is accompanied by HBsAg clearance and seroconversion, HDV-RNA clearance in co-infection, and persistent functional cure of HBV (HBsAg < 0.05 IU/ml, HBV-DNA target not dected, normal alanine aminotransferase) and persistent clearance of HDV RNA. An analysis of HBsAg isoform changes during quantitative HBsAg declines (qHBsAg), and subsequent treatment-free follow-up in the REP 301/REP 301-LTF (HBV/HDV) and REP 401 (HBV) studies was conducted. HBsAg isoforms were analyzed from frozen serum samples using Abbott Research Use Only assays for HBsAg isoforms (large [L], medium [M], and total [T]). The relative change over time in small HBsAg relative to the other isoforms was inferred by the change in the ratio over time of T-HBsAg to M-HBsAg. HBsAg isoform declines followed qHBsAg declines in all participants. No HBsAg isoforms were detectable in any participants with functional cure. HBsAg declines > 2 log₁₀ IU/ml from baseline were correlated with selective clearance of S-HBsAg in 39 of 42 participants. Selective S-HBsAg decline was absent in 9 of 10 participants with HBsAg decline < 2 log₁₀ IU/ml from baseline. Mild qHBsAg rebound during follow-up <10 IU/ml consisted mostly of S-HBsAg and M-HBsAg and not accompanied by significant covalently closed circular DNA activity. Conclusion: The faster observed declines in S-HBsAg indicate the selective clearance of subviral particles from the circulation, consistent with previous mechanistic studies on NAPs. Trace HBsAg rebound in the absence of HBV DNA may reflect HBsAg derived from integrated HBV DNA and not rebound of viral infection.

Liver cancer and hepatic decompensation events in patients hospitalized with viral hepatitis in Spain

BACKGROUND

Chronic viral hepatitis B, C, and D are the main causes of decompensated cirrhosis and liver cancer worldwide. Newborn HBV vaccination was implemented more than 2 decades ago in most EU countries. Furthermore, potent oral antivirals have been available to treat HBV for 15 years and to cure HCV since 2014. The real-life clinical benefits of these interventions at country level have not been assessed, especially regarding major hepatic outcomes such as cirrhotic decompensation events and hepatocellular carcinoma (HCC).

METHODS

Retrospective study of all hospitalizations in Spain having HBV, HCV, and HDV as diagnosis using the Spanish National Registry of Hospital Discharges. Information was retrieved from 1997 up to 2017.

RESULTS

From a total of 73,939,642 hospital admissions during the study period, a diagnosis of HBV, HCV, and HDV was made in 124,915 (1.7‰), 981,985 (13.3‰), and 4850 (0.07‰) patients, respectively. The median age of patients hospitalized within each group was 53.2, 55.9, and 47.0 years, respectively. Significant increases in mean age at hospitalization occurred in all groups (0.6 years older per calendar year on average). The overall rate of hepatic decompensation events for HBV, HCV, and HDV was 12.1%, 14.1%, and 18.8%, respectively. For HCC hospitalizations, these figures were 6.7%, 8.0%, and 7.8%, respectively. Whereas, the rate of decompensation events declined in recent years for HBV, and more recently for HCV, it continued rising up for HDV. Likewise, liver cancer rates recently plateaued for HBV and HCV, but kept growing for HDV.

CONCLUSION

The rate of hepatic decompensation events and liver cancer has declined and/or plateaued in recent years for patients hospitalized with HBV and HCV infections, following the widespread use of oral antiviral therapies for these viruses. In contrast, the rate of decompensated cirrhotic events and HCC has kept rising up for patients with hepatitis delta, for which effective antiviral treatment does not exist yet.

Efficacy and Safety of Bulevirtide plus Tenofovir Disoproxil Fumarate in Real-World Patients with Chronic Hepatitis B and D Co-Infection

Background: The hepatitis B and D virus (HBV/HDV) hepatocyte entry inhibitor bulevirtide (BLV) has been available in Europe since July 2020, after the registrational trial MYR202. Real-life data on the efficacy and safety of BLV are sparse. Methods: We have analysed the course of treatment with BLV (2 mg/day) plus tenofovir disoproxil fumarate (TDF) (245 mg/day) in patients with chronic hepatitis delta (CHD). Virologic (≥2 log reduction in HDV RNA or suppression of HDV RNA below the lower limit of detection) and biochemical (normalisation of serum ALT) treatment responses after 24 weeks were defined according to the MYR202 trial. Results: Seven patients were recruited (four with liver cirrhosis Child−Pugh A). After 24 weeks, a virologic response was observed in five of seven and a biochemical response was seen in three of six patients with elevated serum ALT at baseline. Extended treatment data > 48 weeks were available in three cases: two presented with continuous virologic and biochemical responses and in one individual an HDV-RNA breakthrough was observed. Adverse effects were not recorded. Conclusions: The first real-life data of the approved dosage of 2 mg of BLV in combination with TDF confirm the safety, tolerability, and efficacy of the registrational trial MYR202 for a treatment period of 24 weeks and beyond.

Clinical Application of Droplet Digital PCR for Hepatitis Delta Virus Quantification

Droplet digital PCR (ddPCR) is a novel developed PCR technology providing the absolute quantification of target nucleic acid molecules without the need for a standard curve and regardless PCR amplification efficiency. Our aim was to develop a ddPCR assay for Hepatitis Delta virus (HDV)-RNA viremia quantification and then evaluate its performance in relation to real-time PCR methods. Primers and probe were designed from conserved regions of HDV genome to detect all the 8 HDV genotypes; the World Health Organization (WHO)-HDV international standard was used to calculate the conversion factor transforming results from copies/mL to IU/mL. To evaluate the clinical performance of ddPCR assay, plasma specimens of HDV-infected patients were tested and results were compared with data obtained with two real-time quantitative PCR (RT-qPCR) assays (i.e., in-house assay and commercial RoboGene assay). Analyzing by linear regression a series of 10-fold dilutions of the WHO-HDV International Standard, ddPCR assay showed good linearity with a slope coefficient of 0.966 and R² value of 0.980. The conversion factor from copies to international units was 0.97 and the quantitative linear dynamic range was from 10 to 1 × 10⁶ IU/mL. Probit analysis estimated at 95% an LOD of 9.2 IU/mL. Data from the evaluation of HDV-RNA in routine clinical specimen of HDV patients exhibited strong agreement with results obtained by RT-qPCR showing a concordance correlation coefficient of 0.95. Overall ddPCR and RT-qPCR showed highly comparable technical performance. Moreover, ddPCR providing an absolute quantification method may allow the standardization of HDV-RNA measurement thus improving the clinical and diagnostic management of delta hepatitis.

Signaling Induced by Chronic Viral Hepatitis: Dependence and Consequences

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

Hepatitis D: advances and challenges

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

[Bulevirtide as the first specific agent against hepatitis D virus infections-mechanism and clinical effect]

Die Blockade des Zelleintritts von Krankheitserregern ist ein geeigneter Ansatz, um Neuinfektionen zu verhindern. Der therapeutische Einsatz von Eintrittsinhibitoren bei chronisch infizierten Patienten war jedoch bisher nur begrenzt erfolgreich. Zur Behandlung von chronischen Hepatitis-D-Virus-(HDV-)Infektionen wurde im Juli 2020 mit Bulevirtide (BLV) ein vielversprechender Wirkstoff bedingt zugelassen, der auf diesem Wirkprinzip beruht. Zuvor hatten für HDV keine gezielte Medikation zur Verfügung gestanden und die Behandlung beruhte auf dem Off-Label-Einsatz von Interferon-Alpha/Peginterferon-Alpha (IFNα/Peg-IFNα). In diesem Beitrag wird ein Überblick über die Grundlagen des Wirkmechanismus von BLV gegeben und bisher vorliegende klinische Daten werden zusammengefasst.

Eine HDV-Infektion manifestiert sich als Ko- oder Superinfektion bei Hepatitis-B-Virus-(HBV-)Infektionen und betrifft 4,5–15 % der HBV-Patienten weltweit. HDV nutzt die Hüllproteine von HBV zur Verbreitung. BLV wirkt, indem es den HBV/HDV-Rezeptor natriumtaurocholat-co-transportierendes Polypeptid (NTCP) blockiert und so den Eintritt von HBV/HDV in Hepatozyten verhindert. BLV senkt die HDV-Serum-RNA-Spiegel und führt bei HBV/HDV-infizierten Personen zur Normalisierung der Alanin-Aminotransferase-(ALT-)Werte. Es hat ein ausgezeichnetes Sicherheitsprofil, selbst wenn es über 48 Wochen in hohen Dosen (10 mg täglich) verabreicht wird. In Kombination mit Peg-IFNα zeigt BLV synergistische Effekte auf die Senkung der HDV-RNA im Serum, aber auch auf die Hepatitis-B-Oberflächenantigen-(HBsAg‑)Spiegel. Dies führte bei einer Untergruppe von Patienten zu einer funktionellen Heilung, wenn 2 mg BLV plus Peg-IFNα verabreicht wurden. Der Mechanismus dieser wahrscheinlich immunvermittelten Eliminierung wird in Folgestudien untersucht.

Liver Transplantation for Hepatitis D Virus in the United States: A UNOS Study on Outcomes in the MELD Era

BACKGROUND

Without available curative therapies for delta hepatitis (hepatitis delta virus [HDV]), hepatic decompensation and hepatocellular carcinoma (HCC) among HDV patients often necessitates liver transplantation (LT). The objective of this study was to evaluate outcomes of LT among hepatitis B virus (HBV)/HDV patients in the United States.

METHODS

We performed the first US-based retrospective study of patients who underwent LT for HDV compared with HBV (monoinfection) in the years 2002-2019. We evaluated posttransplant survival and predictors of survival.

RESULTS

We identified a total of 152 HBV/HDV and 5435 HBV patients who underwent LT. HDV patients were younger at transplant (52 versus 55, P < 0.001), less commonly Asian (16% versus 36%, P < 0.001), more likely to be HCV Ab positive (42% versus 28%, P < 0.001), and less likely to be listed for LT with HCC (38% versus 51%, P = 0.001), more likely to have ascites (73% versus 64%, P = 0.019), had worse coagulopathy (mean INR 2.0 versus 1.82, P = 0.04), and were more likely to receive a HCV-positive donor organ (7% versus 3%, P = 0.001). Post-LT overall survival and graft survival were similar between HDV and HBV patients, including among patients with HCC. Older age, HCV coinfection, HCC, and higher model for end-stage liver disease at transplant were associated with higher posttransplant mortality.

CONCLUSIONS

HDV patients were sicker and more likely to be listed for LT for decompensated disease compared with HBV patients. Post-LT survival was similar between HDV and HBV patients, in contrast to prior international studies that suggested worse post-LT survival in HBV patients due to higher rates of HBV reactivation.

Hepatitis B/D-Related Hepatocellular Carcinoma. A Clinical Literature Review

AIM

Given the current literature data, this article aims to shed light on the epidemiological and clinical effects of HBV, as well as its impact on the development of hepatocellular carcinoma (HCC).

METHODS

A review of the English language literature based on a MEDLINE (PubMed) database was searched. The keywords were cirrhosis, hepatocellular carcinoma, epidemiology, hepatitis delta virus, hepatitis B virus, and co-infection. All references from retrieved papers were reviewed systematically to find additional collection of reports.

RESULTS

The study has broadly confirmed the contribution of HDV viremia to liver disease and cirrhosis. However, uncertainty over the mechanism of action on HCC development remains. As the recent data has demonstrated, the HCC-HDV has a unique molecular profile which is distinct from that of HBV-HCC.

CONCLUSION

Owing to the dependence of HDV on HBV, it is not clear whether HCC is a consequence of the cumulative effect of both HBV and HDV, an effect of the underlying cirrhosis, or a direct oncogenic effect of HDV. Many questions concerning the oncogenic role of HDV remain unanswered. To better understand the role of HDV in carcinogenesis, studies at the molecular level that consider genotype differences should be increased. Multicenter, high-volume, and prospective studies that compare HBV/HDV co-infected and HBV-infected individuals will be pivotal in determining the oncogenic role of HDV.

Hepatitis B virus/hepatitis D virus epidemiology: Changes over time and possible future influence of the SARS-CoV-2 pandemic

Hepatitis D virus (HDV) is a defective liver-tropic virus that needs the helper function of hepatitis B virus (HBV) to infect humans and replicate. HDV is transmitted sexually or by a parenteral route, in co-infection with HBV or by super-infection in HBV chronic carriers. HDV infection causes acute hepatitis that may progress to a fulminant form (7%-14% by super-infection and 2%-3% by HBV/HDV co-infection) or to chronic hepatitis (90% by HDV super-infection and 2%-5% by HBV/HDV co-infection), frequently and rapidly progressing to cirrhosis or hepatocellular carcinoma (HCC). Peg-interferon alfa the only recommended therapy, clears HDV in only 10%-20% of cases and, consequently, new treatment strategies are being explored. HDV endemicity progressively decreased over the 50 years from the identification of the virus, due to improved population lifestyles and economic levels, to the use of HBV nuclei(t)side analogues to suppress HBV replication and to the application of universal HBV vaccination programs. Further changes are expected during the severe acute respiratory syndrome coronavirus-2 pandemic, unfortunately towards increased endemicity due to the focus of healthcare towards coronavirus disease 2019 and the consequently lower possibility of screening and access to treatments, lower care for patients with severe liver diseases and a reduced impulse to the HBV vaccination policy.

Optical Biosensors for Diagnostics of Infectious Viral Disease: A Recent Update

The design and development of biosensors, analytical devices used to detect various analytes in different matrices, has emerged. Biosensors indicate a biorecognition element with a physicochemical analyzer or detector, i.e., a transducer. In the present scenario, various types of biosensors have been deployed in healthcare and clinical research, for instance, biosensors for blood glucose monitoring. Pathogenic microbes are contributing mediators of numerous infectious diseases that are becoming extremely serious worldwide. The recent outbreak of COVID-19 is one of the most recent examples of such communal and deadly diseases. In efforts to work towards the efficacious treatment of pathogenic viral contagions, a fast and precise detection method is of the utmost importance in biomedical and healthcare sectors for early diagnostics and timely countermeasures. Among various available sensor systems, optical biosensors offer easy-to-use, fast, portable, handy, multiplexed, direct, real-time, and inexpensive diagnosis with the added advantages of specificity and sensitivity. Many progressive concepts and extremely multidisciplinary approaches, including microelectronics, microelectromechanical systems (MEMSs), nanotechnologies, molecular biology, and biotechnology with chemistry, are used to operate optical biosensors. A portable and handheld optical biosensing device would provide fast and reliable results for the identification and quantitation of pathogenic virus particles in each sample. In the modern day, the integration of intelligent nanomaterials in the developed devices provides much more sensitive and highly advanced sensors that may produce the results in no time and eventually help clinicians and doctors enormously. This review accentuates the existing challenges engaged in converting laboratory research to real-world device applications and optical diagnostics methods for virus infections. The review's background and progress are expected to be insightful to the researchers in the sensor field and facilitate the design and fabrication of optical sensors for life-threatening viruses with broader applicability to any desired pathogens.

Can Interferon therapy change natural course of Hepatitis Delta infection, A clinical and pathological study

Introduction: Chronic delta hepatitis (CDH) has a worser outcome than other viral hepatitis. High dose, long-term Interferon-α (IFNα) is the approved treatment and may ameliorate course. We evaluated long-term histological outcomes of CDH patients treated with IFNα. Method: Histologically proved non-cirrhotic CDH patients treated with high dose IFNα for at least 1 year were grouped as cirrhotic and non-cirrhotic at the end of treatment. Non-cirrhotic patients had also post-treatment liver biopsies. Patients were grouped as histologically responsive and non-responsive regarding fibrosis status. Histological, virological and biochemical courses were analyzed. Results: 48 patients were treated with IFNα (conventional and/or pegylated) for median 24 months with a post-treatment follow-up of 5 years. During the follow-up, cirrhosis developed in 24 patients, 5 of whom were decompensated. There was no difference between pre- and post-treatment fibrosis scores of 24 non-cirrhotic patients at the end of follow-up. Among patients; 13% (n:6) had decreased, 21%(n:10) had steady and 16% (n:8) had increased fibrosis scores. Persistent viral response (PVR) was achieved in 16 patients (33%). 20% of entire group was histologically responsive (decreasing or steady fibrosis scores with improved necro-inflammatory score) while near 80% had histological progression/cirrhosis. PVR was significantly associated with histological response. Conclusions: Long-term natural course of patients who were treated with high dose IFNα for at least one year was evaluated clinically and histologically. Despite the association of PVR with histological response, IFNα treatment didn't change the natural course of CDH, clinical and histological progression continued in two-thirds of the cases despite treatment.

Viral Hepatitis and Hepatocellular Carcinoma: State of the Art

Viral hepatitis is one of the main causes leading to hepatocellular carcinoma (HCC). The continued rise in incidence of HCC suggests additional factors following infection may be involved. This review examines recent studies investigating the molecular mechanisms of chronic hepatitis and its association with hepatocarcinogenesis. Hepatitis B virus patients with genotype C display an aggressive disease course leading to HCC more than other genotypes. Furthermore, hepatitis B excretory antigen (HBeAg) seems to be a more sensitive predictive tumor marker exhibiting a six-fold higher relative risk in patients with positive HBsAg and HBeAg than those with HBsAg only. Single or combined mutations of viral genome can predict HCC development in up to 80% of patients. Several mutations in HBx-gene are related with higher HCC incidence. Overexpression of the core protein in HCV leads to hepatocellular lipid accumulation associated with oncogenesis. Reduced number and decreased functionality of natural killer cells in chronic HCV individuals dysregulate their surveillance function in tumor and viral cells resulting in HCC. Furthermore, high T-cell immunoglobulin and mucin 3 levels supress CD8+ T-cells, which lead to immunological dysregulation. Hepatitis D promotes HCC development indirectly via modifications to innate immunity, epigenetic alterations and production of reactive oxygen species with the LHDAg being the most highly associated with HCC development. Summarizing the results, HBV and HCV infection represent the most associated forms of viral hepatitis causing HCC. Further studies are warranted to further improve the prediction of high-risk patients and development of targeted therapeutics preventing the transition from hepatic inflammation–fibrosis to cancer.

The global hepatitis delta virus (HDV) epidemic: what gaps to address in order to mount a public health response?

BACKGROUND

Co-infection between hepatitis B virus (HBV) and hepatitis delta virus (HDV) causes the severest chronic hepatitis and is associated with a high risk of cirrhosis and hepatocellular carcinoma (HCC). The Global Health Sector Strategy on Viral Hepatitis called for the elimination of hepatitis (- 65% mortality and - 90% incidence) by 2030. Our aims were to summarize key points of knowledge and to identify the gaps that need to be addressed to mount a public health response to HDV.

METHODS

We performed a current literature review in terms of epidemiology by WHO regions, genotypes distribution and their pathogenicity, factors associated with HDV infection, mortality due to HDV infection, testing strategies and treatment.

RESULTS

Prevalence of infection and genotypes are heterogeneous distributed, with highest prevalence in foci around the Mediterranean, in the Middle East, and in Central, Northern Asia and Eastern Asia. Persons who inject drugs (PWID) and migrants from highly endemic areas are highly affected. While antibody detection tests are available, HDV RNA tests of current infection are not standardized nor widely available. The few therapeutic options, including lofartinib, are not widely available; however several new and promising agents have entered clinical trials.

CONCLUSION

HDV infection is an poorly known cause of chronic liver disease. To mount a public health response, we need a better description of the HDV epidemic, standardized testing strategies and better treatment options.

Ergosterol peroxide inhibits HBV infection by inhibiting the binding of the pre-S1 domain of LHBsAg to NTCP

Hepatitis B virus (HBV) infection leads to severe liver diseases, including cirrhosis and hepatocellular carcinoma (HCC). More than 257 million individuals are chronically infected, particularly in the Western Pacific region and Africa. Although nucleotide and nucleoside analogues (NUCs) and interferons (IFNs) are the standard therapeutics for HBV infection, none eradicates HBV covalently closed circular DNA (cccDNA) from the infected hepatocytes. In addition, long-term treatment with NUCs increases the risk of developing drug resistance and IFNs may cause severe side effects in patients. Thus, a novel HBV therapy that can achieve a functional cure, or even complete elimination of the virus, is highly desirable. Regarding the HBV life cycle, agents targeting the entry step of HBV infection reduce the intrahepatic cccDNA pool preemptively. The initial entry step in HBV infection involves interaction between the pre-S1 domain of the large hepatitis B surface protein (LHBsAg) and the sodium taurocholate cotransporting polypeptide (NTCP), which is a receptor for HBV. In this study, ergosterol peroxide (EP) was identified as a new inhibitor of HBV entry. EP inhibits an early step of HBV entry into DMSO-differentiated immortalized primary human hepatocytes HuS-E/2 cells, which were overexpressed NTCP. Also, EP interfered directly with the NTCP-LHBsAg interaction by acting on the NTCP. In addition, EP had no effect on HBV genome replication, virion integrity or virion secretion. Finally, the activity of EP against infection with HBV genotypes A-D highlights the therapeutic potential of EP for fighting HBV infection.

Asociación Mexicana de Hepatología A.C. Clinical guideline on hepatitis B

Hepatitis B virus (HBV) infection continues to be a worldwide public health problem. In Mexico, at least three million adults are estimated to have acquired hepatitis B (total hepatitis B core antibody [anti-HBc]-positive), and of those, 300,000 active carriers (hepatitis B surface antigen [HBsAg]-positive) could require treatment. Because HBV is preventable through vaccination, its universal application should be emphasized. HBV infection is a major risk factor for developing hepatocellular carcinoma. Semi-annual liver ultrasound and serum alpha-fetoprotein testing favor early detection of that cancer and should be carried out in all patients with chronic HBV infection, regardless of the presence of advanced fibrosis or cirrhosis. Currently, nucleoside/nucleotide analogues that have a high barrier to resistance are the first-line therapies.

Asociación Mexicana de Hepatología A.C. Clinical guideline on hepatitis B

Hepatitis B virus (HBV) infection continues to be a worldwide public health problem. In Mexico, at least three million adults are estimated to have acquired hepatitis B (total hepatitis B core antibody [anti-HBc]-positive), and of those, 300,000 active carriers (hepatitis B surface antigen [HBsAg]-positive) could require treatment. Because HBV is preventable through vaccination, its universal application should be emphasized. HBV infection is a major risk factor for developing hepatocellular carcinoma. Semi-annual liver ultrasound and serum alpha-fetoprotein testing favor early detection of that cancer and should be carried out in all patients with chronic HBV infection, regardless of the presence of advanced fibrosis or cirrhosis. Currently, nucleoside/nucleotide analogues that have a high barrier to resistance are the first-line therapies.

Reliable quantification of plasma HDV RNA is of paramount importance for treatment monitoring: A European multicenter study

OBJECTIVES

Quantification of plasma hepatitis D virus (HDV) RNA is the essential tool for patient management under antiviral therapy. The aim of this European multicenter study was to improve the comparability of quantitative results reported by different laboratories using the CE/IVD-labeled RoboGene HDV RNA Quantification Kit 2.0 (Roboscreen GmbH) with different manual or automated nucleic acid extraction protocols/platforms and amplification/detection devices.

METHODS

For harmonization of HDV RNA concentrations obtained by different protocols, correction factors (CF) were determined using the 1st WHO International Standard for HDV RNA. The limit of detection (LOD) and accuracy were determined for each protocol by using reference material. Furthermore, clinical samples were analyzed and results compared.

RESULTS

The CF ranged from 20 to 1,870 depending on the protocol used. The LOD was found between 4 and 450 IU/ml. When accuracy was tested, external quality control (EQC) samples containing low HDV RNA concentrations were not detected by those protocols with higher LODs. For EQC samples, the maximum standard deviation of HDV RNA concentrations was found to be 0.53 log₁₀ IU/ml, for clinical samples 0.87 log₁₀ IU/mL.

CONCLUSION

To ensure reliability in quantification of HDV RNA, any modification of the extraction and amplification/detection protocol validated by the manufacturer requires revalidation. With the 1st WHO International Standard for HDV RNA, the CF could easily be calculated leading to harmonization of quantitative results. This warrants both accurate monitoring of response to existing anti-HDV treatment and comparability of study results investigating novel anti-HDV drugs.

Detection and Genetic Characterization of Hepatitis B and D Viruses: A Multi-Site Cross-Sectional Study of People Who Use Illicit Drugs in the Amazon Region

Hepatitis B (HBV) and delta (HDV) viruses are endemic in the Amazon region, but vaccine coverage against HBV is still limited. People who use illicit drugs (PWUDs) represent a high-risk group due to common risk behavior and socioeconomic factors that facilitate the acquisition and transmission of pathogens. The present study assessed the presence of HBV and HBV-HDV co-infection, identified viral sub-genotypes, and verified the occurrence of mutations in coding regions for HBsAg and part of the polymerase in HBV-infected PWUDs in municipalities of the Brazilian states of Amapá and Pará, in the Amazon region. In total, 1074 PWUDs provided blood samples and personal data in 30 municipalities of the Brazilian Amazon. HBV and HDV were detected by enzyme-linked immunosorbent assay and polymerase chain reaction. Viral genotypes were identified by nucleotide sequencing followed by phylogenetic analysis, whereas viral mutations were analyzed by specialized software. High rates of serological (32.2%) and molecular (7.2%) markers for HBV were detected, including cases of occult HBV infection (2.5%). Sub-genotypes A1, A2, D4, and F2a were most frequently found. Escape mutations due to vaccine and antiviral resistance were identified. Among PWUDs with HBV DNA, serological (19.5%) and molecular (11.7%) HDV markers were detected, such as HDV genotypes 1 and 3. These are worrying findings, presenting clear implications for urgent prevention and treatment needs for the carriers of these viruses.

Viral hepatitis update: Progress and perspectives

Viral hepatitis, secondary to infection with hepatitis A, B, C, D, and E viruses, are a major public health problem and an important cause of morbidity and mortality. Despite the huge medical advances achieved in recent years, there are still points of conflict concerning the pathogenesis, immune response, development of new and more effective vaccines, therapies, and treatment. This review focuses on the most important research topics that deal with issues that are currently being solved, those that remain to be solved, and future research directions. For hepatitis A virus we will address epidemiology, molecular surveillance, new susceptible populations as well as environmental and food detections. In the case of hepatitis B virus, we will discuss host factors related to disease, diagnosis, therapy, and vaccine improvement. On hepatitis C virus, we will focus on pathogenesis, immune response, direct action antivirals treatment in the context of solid organ transplantation, issues related to hepatocellular carcinoma development, direct action antivirals resistance due to selection of resistance-associated variants, and vaccination. Regarding hepatitis D virus, we describe diagnostic methodology, pathogenesis, and therapy. Finally, for hepatitis E virus, we will address epidemiology (including new emerging species), diagnosis, clinical aspects, treatment, the development of a vaccine, and environmental surveillance.