Hepatitis D prevalence: problems with extrapolation to global population estimates

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

OBJECTIVE

Infection with the hepatitis delta virus (HDV), a unique RNA virus that requires hepatitis B virus (HBV) antigens for its assembly, replication, and transmission, causes severe viral hepatitis. Compared to HBV monoinfection, HDV infection increases the risk of severe liver disease, necessity for liver transplant, and mortality. Global HDV prevalence estimates vary from 5% to 15% among persons with HBV, but screening guidelines for HDV are inconsistent; some recommend risk-based screening, while others recommend universal screening for all people with HBV. Among primary care providers (PCPs) in the US, there is a lack of awareness and/or insufficient adherence to current recommendations for the screening of HDV infection and management of chronic HDV.

METHODS

Publications were obtained by conducting literature searches between July and August 2022 using the PubMed database and by manual searches of the retrieved literature for additional references. Information was synthesized to highlight HDV screening and management strategies for PCPs. Best practices for PCPs based on current guidelines and comanagement strategies for patients with HBV and HDV infection were summarized.

RESULTS

We recommend universal screening for HDV in patients positive for hepatitis B surface antigen. Confirmed HDV infection should prompt evaluation by a liver specialist, if available, with whom the PCP can comanage the patient. PCPs should counsel patients on the expected course of the disease, lifestyle factors that may influence liver health, need for consistent disease monitoring and follow-up, and risk of disease transmission. Screening is suggested for sexual partners, household contacts, and family members, with HBV immunization recommended for those found to be susceptible. There are currently no US Food and Drug Administration-approved therapies for HDV infection; thus, management is limited to treatments for chronic HBV infection plus long-term monitoring of liver health.

CONCLUSIONS

PCPs can be a valuable point of care for patients to access HDV/HBV screening, HBV immunization, and education, and can comanage patients with HBV and/or HDV infection.

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.

Adjusted estimate of the prevalence of hepatitis delta virus in 25 countries and territories

BACKGROUND & AIMS

Hepatitis delta virus (HDV) is a satellite RNA virus that requires the hepatitis B virus (HBV) for assembly and propagation. Individuals infected with HDV progress to advanced liver disease faster than HBV-monoinfected individuals. Recent studies have estimated the global prevalence of anti-HDV antibodies among the HBV-infected population to be 5-15%. This study aimed to better understand HDV prevalence at the population level in 25 countries/territories.

METHODS

We conducted a literature review to determine the prevalence of anti-HDV and HDV RNA in hepatitis B surface antigen (HBsAg)-positive individuals in 25 countries/territories. Virtual meetings were held with experts from each setting to discuss the findings and collect unpublished data. Data were weighted for patient segments and regional heterogeneity to estimate the prevalence in the HBV-infected population. The findings were then combined with The Polaris Observatory HBV data to estimate the anti-HDV and HDV RNA prevalence in each country/territory at the population level.

RESULTS

After adjusting for geographical distribution, disease stage and special populations, the anti-HDV prevalence among the HBsAg+ population changed from the literature estimate in 19 countries. The highest anti-HDV prevalence was 60.1% in Mongolia. Once adjusted for the size of the HBsAg+ population and HDV RNA positivity rate, China had the highest absolute number of HDV RNA+ cases.

CONCLUSIONS

We found substantially lower HDV prevalence than previously reported, as prior meta-analyses primarily focused on studies conducted in groups/regions that have a higher probability of HBV infection: tertiary care centers, specific risk groups or geographical regions. There is large uncertainty in HDV prevalence estimates. The implementation of reflex testing would improve estimates, while also allowing earlier linkage to care for HDV RNA+ individuals. The logistical and economic burden of reflex testing on the health system would be limited, as only HBsAg+ cases would be screened.

IMPACT AND IMPLICATIONS

There is a great deal of uncertainty surrounding the prevalence of hepatitis delta virus among people living with hepatitis B virus at the population level. In this study, we aimed to better understand the burden in 25 countries and territories, to refine techniques that can be used in future analyses. We found a lower prevalence in the majority of places studied than had been previously reported. These data can help inform policy makers on the need to screen people living with hepatitis B virus to find those coinfected with hepatitis delta virus and at high risk of progression, while also highlighting the pitfalls that other researchers have often fallen into.

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.

Sexual Transmission of Viral Hepatitis

Ongoing sexual transmission presents a significant barrier to viral hepatitis control. Endemic transmission of hepatitis A virus continues through communities of men with male sex partners, despite vaccine availability. Increased incidence of hepatitis B virus from 2014-2018 prompted expanded vaccination guidelines, but uptake and physician awareness remain poor. Hepatitis C virus while strongly associated with injection drug use, is also transmitted by high-risk sexual contact. Despite universal screening recommendations and curative treatment, incidence continues to increase. Even with safe and highly effective vaccinations or treatments, sexual transmission of viral hepatitides must be addressed to achieve disease elimination.

Epidemiology, presentation, and therapeutic approaches for hepatitis D infections

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Delta hepatitis epidemiology and the global burden of disease

Delta Hepatitis is considered the most severe form of hepatitis, with varied prevalence, genotype distribution and risk factors worldwide. Current knowledge of global epidemiology is limited due to variable screening practices for HDV. Here, we summarize what is currently known about the prevalence of testing and prevalence of HDV positivity globally.

Viral hepatitis and hepatocellular carcinoma: From molecular pathways to the role of clinical surveillance and antiviral treatment

Hepatocellular carcinoma (HCC) is a global health challenge. Due to the high prevalence in low-income countries, hepatitis B virus (HBV) and hepatitis C virus infections remain the main risk factors for HCC occurrence, despite the increasing frequencies of non-viral etiologies. In addition, hepatitis D virus coinfection increases the oncogenic risk in patients with HBV infection. The molecular processes underlying HCC development are complex and various, either independent from liver disease etiology or etiology-related. The reciprocal interlinkage among non-viral and viral risk factors, the damaged cellular microenvironment, the dysregulation of the immune system and the alteration of gut-liver-axis are known to participate in liver cancer induction and progression. Oncogenic mechanisms and pathways change throughout the natural history of viral hepatitis with the worsening of liver fibrosis. The high risk of cancer incidence in chronic viral hepatitis infected patients compared to other liver disease etiologies makes it necessary to implement a proper surveillance, both through clinical-biochemical scores and periodic ultrasound assessment. This review aims to outline viral and microenvironmental factors contributing to HCC occurrence in patients with chronic viral hepatitis and to point out the importance of surveillance programs recommended by international guidelines to promote early diagnosis of HCC.

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.

Human hepatitis D virus-specific T cell epitopes

HDV is a small, defective RNA virus that requires the HBsAg of HBV for its assembly, release, and transmission. Chronic HBV/HDV infection often has a severe clinical outcome and is difficult to treat. The important role of a robust virus-specific T cell response for natural viral control has been established for many other chronic viral infections, but the exact role of the T cell response in the control and progression of chronic HDV infection is far less clear. Several recent studies have characterised HDV-specific CD4+ and CD8+ T cell responses on a peptide level. This review comprehensively summarises all HDV-specific T cell epitopes described to date and describes our current knowledge of the role of T cells in HDV infection. While we now have better tools to study the adaptive anti-HDV-specific T cell response, further efforts are needed to define the HLA restriction of additional HDV-specific T cell epitopes, establish additional HDV-specific MHC tetramers, understand the degree of cross HDV genotype reactivity of individual epitopes and understand the correlation of the HBV- and HDV-specific T cell response, as well as the breadth and specificity of the intrahepatic HDV-specific T cell response.

Current status of hepatitis delta

Hepatitis D virus (HDV) infection in patients chronically infected with hepatitis B virus (HBV) causes the most severe form of chronic viral hepatitis and continues to represent a major health problem. The latest data show that the global prevalence is much higher than previously considered. Therefore, screening with the detection of anti-HDV antibodies is mandatory for all chronic HBV patients. In spite of the severity of liver disease, the only recommended treatment today is pegylated interferon-alpha, which has limited efficacy. Novel host-targeting molecules are now under investigation. The current phase 2 clinical trials include pegylated interferon-lambda, bulevirtide, lonafarnib, and REP-2139. This review focuses on the current status of epidemiology, diagnosis, and treatment of HDV infection.

[Clinical course and outcomes of chronic viral hepatitis D in patients from Republic of Tuva as endemic region]

INTRODUCTION

Hepatitis D (delta, 5) is caused by an RNA virus (hepatitis D virus, HDV) from genus Deltavirus, and is the most severe and difficult to treat disease among both viral hepatitis and infectious diseases in general. The development of HDV infection in the host organism is possible only in the presence of hepatitis B virus (HBV). Coinfection with HBV and HDV is associated with a more rapid progression of chronic viral hepatitis (CVH) to liver cirrhosis (LC) and an unfavorable outcome in comparison with HBV monoinfection. Data on the influence of clinical, biochemical and virological factors on the infectious process in patients with hepatitis D are limited due to the insufficient amount of research on this theme.The study aimed to determine demographic, clinical, biochemical, and virological factors influencing the course and progression of CVH D in patients followed during 10 years, residing in the territory of the Tuva Republic, one of the endemic regions of the Russian Federation.

MATERIAL AND METHODS

Changes in clinical and laboratory parameters were analyzed in dynamics in 121 HDV infected patients with a different course of the disease, who were under observation from 2009 to 2019. Three groups of patients were identified: group 1 - 61 patients with disease progression of chronic hepatitis to LC (Child-Pugh class B-C), group 2 - 49 patients with non-progressive chronic hepatitis, and group 3 - 11 patients with slowly progressive LC (class A). Demographic data, the presence of detectable HBV DNA, indicators of the functional state of the liver: alanine aminotransferase (ALT/GPT), aspartate aminotransferase (AST/GOT), alkaline phosphatase (ALP), gamma-glutamyltransferase (GGT), and total bilirubin content were analyzed. The severity of hepatic encephalopathy was assessed by the duration of the numbers connection test (NCT).

RESULTS

All patients belonged to the same ethnic group (Tuvinians), were infected with HDV genotype 1 and were positive for HDV RNA throughout the entire follow-up period. There were no significant differences in sex ratio and mean age at the time of inclusion in the study between the groups. In group 1, the average number of years from inclusion in the study to the formation of LC was 3.65 ± 2.3 years, years to the lethal outcome: 4.5 ± 3 years. Significantly higher levels of AST/GOT, ALP, GGT, total bilirubin (TB) and NCT grade were found in group 1 compared to group 2. ALT/GPT levels did not differ significantly in these groups. When comparing groups with disease progression and slowly progressive LC (groups 1 and 3), no significant differences were found in any of the clinical and biochemical parameters. ALT/GPT, GGT, TB and NCT values were significantly higher in patients with slowly progressive LC (group 3) compared to group 2. No differences in AST/GOT and ALP levels were found between these groups. Detectable HBV DNA was significantly more frequent in patients with progressive disease and with chronic viral hepatitis than in patients with slowly progressive LC. There were no significant differences in the frequency of HBV DNA detection in patients from groups 1 and 2.

CONCLUSION

The results obtained on a relatively homogeneous cohort demonstrated that age and gender are not the factors influencing the progression of chronic viral hepatitis D to cirrhosis. The lack of detectable HBV DNA is associated with the slow progression of LC. The revealed differences in clinical and biochemical parameters reflect the degree of functional liver damage in chronic viral hepatitis D and HDV-associated cirrhosis.

Serological detection of hepatitis B and D virus co-infection among patients attending a tertiary health facility at Maiduguri, Nigeria

Background

Hepatitis D virus (HDV) is highly pathogenic, and clinical studies revealed that HDV infection aggravates the natural history of the underlying hepatitis B virus (HBV) infection by progression to cirrhosis that leads to early decompensation of liver function compared with HBV mono-infection. To determine the seroprevalence of HDV among HBsAg-seropositive patients and associated biochemical profiles at Maiduguri, Nigeria, a hospital-based cross-sectional study on 180 sera of patients positive for HBsAg by ELISA were evaluated for anti-HDV, hepatitis B envelop antigen, anti-HBs antibodies and liver enzyme profiles.

Results

HDV seroprevalence of 3.3% among 180 HBsAg-positive patients. Relatively higher seroprevalence of HDV was observed in males (4.3%) than in females (2.3%). The highest infection rate (20%) was obtained in patients ≥ 56 years. However, no significant association between positive anti-HDV seroprevalence and gender (p > 0.05). Of the 6 (3.3%) anti-HDV-positive patients, only 1 (16.7%) was positive for HBeAg while all were negative for anti-HBs antibodies. The mean level of liver enzyme level of AST and ALT of the anti-HDV-positive patients significantly differ from that of HBsAg mono-infected patients (p ˂ 0.05). However, no significant difference (p < 0.05) between the mean levels of liver enzymes of ALP in anti-HDV-positive and HBsAg mono-infected patients (p ˃ 0.05) was found.

Conclusion

This study revealed a relatively low presence of HDV in HBsAg-positive patients. Furthermore, HDV-HBV co-infected patients had somewhat worse liver enzyme upregulation. This underscores the need for rapid HDV testing and treatment in HBV-infected patients.

Ten-year follow-up of a randomized controlled clinical trial in chronic hepatitis delta

Hepatitis delta virus (HDV) infection causes the most severe form of viral hepatitis. PEG-interferon alpha-2a (PEG-IFNα-2a) is the only effective treatment but its long-term clinical impact is unclear. The aim of this study was to investigate the long-term outcome after 48 weeks of pegylated interferon alpha-2a therapy. We performed a retrospective follow-up study of the Hep-Net-International-Delta-Hepatitis-Intervention-Study 1 (HIDIT-I trial). Patients had received 48 weeks of treatment with either PEG-IFNα-2a plus adefovir dipivoxil (ADV) (Group I), PEG-IFNα-2a alone (Group II) or adefovir dipivoxil alone (Group III). Liver-related complications were defined as liver-related death, liver transplantation, liver cancer and hepatic decompensation defined as development of Child-Pugh scores B or C or an increase in Model for End-stage Liver Disease (MELD) scores of five or more points in relation to baseline values. Patients were considered for further analysis when they were retreated with PEG-IFNα-2a. Follow-up data (at least 1 visit beyond post-treatment week 24) were available for 60 patients [Group I, (n = 19), Group II (n = 20), Group III (n = 21)]. Mean time of follow-up was 8.9 (1.6 - 13.4) years. 19 patients were retreated with IFN-based therapy: 42% (n = 8) in PEG-IFNα-2a arms and 58% (n = 11) in the adefovir only arm. Clinical complications on long-term follow-up occurred in 17 patients and were associated with nonresponse to therapy and baseline cirrhosis. The annual event-free survival rate in patients with cirrhosis vs noncirrhotic patients at year 5 and 10 was 70% vs 91% and 35% vs 76%. Long-term follow-up of a large randomized clinical trial suggests that off-treatment HDV RNA response to PEG-IFNα-2a treatment leads to improved clinical long-term outcome.

Chronic hepatitis D and hepatocellular carcinoma: A systematic review and meta-analysis of observational studies

BACKGROUND & AIMS

Chronic hepatitis D (CHD) is the most severe form of chronic viral hepatitis but its role in the development of hepatocellular carcinoma (HCC) remains debated. We conducted a systematic review and meta-analysis of epidemiological studies to examine whether CHD is associated with an increased risk of HCC.

METHODS

We searched PubMed, Embase and Web of Science, as well as study references and conference proceedings. We considered cohort and case-control studies allowing the calculation of effect estimates for the association between CHD (exposure) and HCC (outcome) in comparison to chronic hepatitis B. Data extraction and quality evaluation (using the Newcastle-Ottawa scale) were performed independently by 2 authors. Data were pooled using random-effects models.

RESULTS

Ninety-three studies (68 case-control studies including 22,862 patients and 25 cohort studies including 75,427 patients) were included. Twelve studies accounted for confounders, in either study design or analysis (10 of which were cohorts), and 11 cohorts were prospective. The overall analysis showed a significantly increased risk of HCC in patients with CHD, despite substantial study heterogeneity (pooled odds ratio 1.28; 95% CI 1.05-1.57; I² = 67.0%). The association was particularly strong in the absence of heterogeneity for prospective cohort studies (pooled odds ratio 2.77; 95% CI 1.79-4.28; I² = 0%), and studies with HIV-infected patients (pooled odds ratio 7.13; 95% CI 2.83-17.92; I² = 0%).

CONCLUSIONS

We found a significantly higher risk of HCC in patients with CHD. Although further studies are needed to definitively exclude a potential bias due to antiviral treatments, our findings highlight the rationale for improved screening of hepatitis D virus infection in patients with chronic hepatitis B, and the urgent need for novel and effective antiviral therapies.

LAY SUMMARY

Hepatitis D virus (HDV) is a defective pathogen requiring hepatitis B virus (HBV) to complete its life cycle. Chronic hepatitis D is the most severe form of chronic viral hepatitis, increasing the risk of cirrhosis, liver decompensation and death compared to HBV monoinfection. However, the association between HDV infection and increased risk of hepatocellular carcinoma is debated. We conducted a systematic review and found that patients with HDV infection had a significantly higher risk of developing hepatocellular carcinoma than those with HBV monoinfection.

The global prevalence of hepatitis D virus infection: Systematic review and meta-analysis

BACKGROUND AND AIMS

There are uncertainties about the epidemic patterns of HDV infection and its contribution to the burden of liver disease. We estimated the global prevalence of HDV infection and explored its contribution to the development of cirrhosis and hepatocellular carcinoma (HCC) among HBsAg-positive people.

METHODS

We searched Pubmed, EMBASE and Scopus for studies reporting on total or IgG anti-HDV among HBsAg-positive people. Anti-HDV prevalence was estimated using a binomial mixed model, weighting for study quality and population size. The population attributable fraction (PAF) of HDV to cirrhosis and HCC among HBsAg-positive people was estimated using random effects models.

RESULTS

We included 282 studies, comprising 376 population samples from 95 countries, which together tested 120,293 HBsAg-positive people for anti-HDV. The estimated anti-HDV prevalence was 4.5% (95% CI 3.6-5.7) among all HBsAg-positive people and 16.4% (14.6-18.6) among those attending hepatology clinics. Worldwide, 0.16% (0.11-0.25) of the general population, totalling 12.0 (8.7-18.7) million people, were estimated to be anti-HDV positive. Prevalence among HBsAg-positive people was highest in Mongolia, the Republic of Moldova and countries in Western and Middle Africa, and was higher in injecting drug users, haemodialysis recipients, men who have sex with men, commercial sex workers, and those with HCV or HIV. Among HBsAg-positive people, preliminary PAF estimates of HDV were 18% (10-26) for cirrhosis and 20% (8-33) for HCC.

CONCLUSIONS

An estimated 12 million people worldwide have experienced HDV infection, with higher prevalence in certain geographic areas and populations. HDV is a significant contributor to HBV-associated liver disease. More quality data are needed to improve the precision of burden estimates.

LAY SUMMARY

We combined all available studies to estimate how many people with hepatitis B also have hepatitis D, a viral infection that only affects people with hepatitis B. About 1 in 22 people with hepatitis B also have hepatitis D, increasing to 1 in 6 when considering people with liver disease. Hepatitis D may cause about 1 in 6 of the cases of cirrhosis and 1 in 5 of the cases of liver cancer that occur in people with hepatitis B. Hepatitis D is an important contributor to the global burden of liver disease.

Performance of commercially available anti-HDV enzyme-linked immunosorbent assays in Taiwan

Background

Hepatitis D virus (HDV) infection is a major global health issue around the world. There are approximately 15–20 million individuals infected with HDV worldwide. HDV infection usually causes increased mortality compared with infection with hepatitis B virus (HBV) alone. However, testing for the detection of HDV is not widely available in Taiwan. Therefore, the General Biologicals Corporation (GB) HDV Ab kit was developed for detecting anti-HDV antibodies.

Methods

A total of 913 serum and 462 EDTA-treated plasma samples were obtained from HBsAg-positive individuals in three hospitals in Taiwan from June 2014 to November 2017. We used three commercially available ELISA kits, DiaPro HDV Ab, DiaSorin ETI-AB-DELTAK-2 and GB HDV Ab, which were utilized strictly according to the instructions of the manufacturers.

Results

A comparative study of the results from the GB HDV Ab kit and the other commercial ELISA kits (DiaPro and DiaSorin) was performed to determine their efficacy for anti-HDV detection. The results indicated that the sensitivity of the GB HDV Ab kit for serum and EDTA samples was 100% compared to that of the DiaPro and DiaSorin kits, whereas the specificity for serum and EDTA samples was 99.3 and 98.1%, respectively. In addition, the overall agreement of the results of the GB HDV Ab kit for the serum and EDTA samples was 99.3 and 98.3%, respectively. It is worth noting that the performance of the GB HDV Ab kit was not affected by interference from triglyceride, bilirubin, hemoglobin, or human anti-mouse antibody. The limit of detection of the GB HDV Ab kit is approximately 100-fold lower than that of the other two commercial kits.

Conclusions

The GB HDV Ab kit, which presented equivalent sensitivity and specificity compared to both certified anti-HDV kits, would be a suitable kit for HDV diagnosis in Taiwan.

Estimating the Global Prevalence, Disease Progression, and Clinical Outcome of Hepatitis Delta Virus Infection

BACKGROUND

Hepatitis delta virus (HDV) coinfects with hepatitis B virus (HBV) causing the most severe form of viral hepatitis. However, its exact global disease burden remains largely obscure. We aim to establish the global epidemiology, infection mode-stratified disease progression, and clinical outcome of HDV infection.

METHODS

We conducted a meta-analysis with a random-effects model and performed data synthesis.

RESULTS

The pooled prevalence of HDV is 0.80% (95% confidence interval [CI], 0.63-1.00) among the general population and 13.02% (95% CI, 11.96-14.11) among HBV carriers, corresponding to 48-60 million infections globally. Among HBV patients with fulminant hepatitis, cirrhosis, or hepatocellular carcinoma, HDV prevalence is 26.75% (95% CI, 19.84-34.29), 25.77% (95% CI, 20.62-31.27), and 19.80% (95% CI, 10.97-30.45), respectively. The odds ratio (OR) of HDV infection among HBV patients with chronic liver disease compared with asymptomatic controls is 4.55 (95% CI, 3.65-5.67). Hepatitis delta virus-coinfected patients are more likely to develop cirrhosis than HBV-monoinfected patients with OR of 3.84 (95% CI, 1.79-8.24). Overall, HDV infection progresses to cirrhosis within 5 years and to hepatocellular carcinoma within 10 years, on average.

CONCLUSIONS

Findings suggest that HDV poses a heavy global burden with rapid progression to severe liver diseases, urging effective strategies for screening, prevention, and treatment.

Advances in hepatitis B therapeutics

Despite the availability of both effective preventive vaccines and oral antivirals, over 250 million people are chronically infected with the hepatitis B virus (HBV). Globally, chronic hepatitis B is the leading cause of hepatocellular carcinoma, which represents the third cause of cancer mortality, accounting for nearly 1 million annual deaths. Current oral nucleos(t)ide therapy with tenofovir or entecavir suppresses serum HBV-DNA in most treated patients, but rarely is accompanied by HBsAg loss. Thus, treatment has to be given lifelong to prevent viral rebound. A broad spectrum of antivirals that block the HBV life cycle at different steps are in clinical development, including entry inhibitors, cccDNA disrupters/silencers, translation inhibitors, capsid assembly modulators, polymerase inhibitors and secretion inhibitors. Some of them exhibit higher potency than current oral nucleos(t)ides. Drugs in more advanced stages of clinical development are bulevirtide, JNJ-6379, ABI-H0731, ARO-HBV and REP-2139. To date, only treatment with ARO-HBV and with REP-2139 have resulted in HBsAg loss in a significant proportion of patients. Combination therapies using distinct antivirals and/or immune modulators are expected to maximize treatment benefits. The current goal is to achieve a 'functional cure', with sustained serum HBsAg after drug discontinuation. Ultimately, the goal of HBV therapy will be virus eradication, an achievement that would require the elimination of the cccDNA reservoir within infected hepatocytes.

The oncogenic role of hepatitis delta virus in hepatocellular carcinoma

Hepatitis delta virus (HDV) is a small defective virus that needs hepatitis B virus (HBV) to replicate and propagate. HDV infection affects 20-40 million people worldwide and pegylated interferon (PegIFN) is the only recommended therapy. There is limited data on the contribution of HDV infection to HBV-related liver disease or liver cancer. Evidence from retrospective and cohort studies suggests that HBV/HDV coinfection accelerates progression to cirrhosis and is associated with an increased risk of hepatocellular carcinoma (HCC) development compared to HBV monoinfection. Although the life cycle of HDV is relatively well known, there is only ancillary information on the molecular mechanisms that can drive specific HDV-related oncogenesis. No thorough reports on the specific landscape of mutations or molecular classes of HDV-related HCC have been published. This information could be critical to better understand the uniqueness, if any, of HDV-related HCC and help identify novel targetable mutations. Herein, we review the evidence supporting an oncogenic role of HDV, the main reported mechanisms of HDV involvement and their impact on HCC development.

A review on hepatitis D: From virology to new therapies

Hepatitis delta virus (HDV) is a defective virus that requires the hepatitis B virus (HBV) to complete its life cycle in human hepatocytes. HDV virions contain an envelope incorporating HBV surface antigen protein and a ribonucleoprotein containing the viral circular single-stranded RNA genome associated with both forms of hepatitis delta antigen, the only viral encoded protein. Replication is mediated by the host cell DNA-dependent RNA polymerases. HDV infects up to72 million people worldwide and is associated with an increased risk of severe and rapidly progressive liver disease. Pegylated interferon-alpha is still the only available treatment for chronic hepatitis D, with poor tolerance and dismal success rate. Although the development of antivirals inhibiting the viral replication is challenging, as HDV does not possess its own polymerase, several antiviral molecules targeting other steps of the viral life cycle are currently under clinical development: Myrcludex B, which blocks HDV entry into hepatocytes, lonafarnib, a prenylation inhibitor that prevents virion assembly, and finally REP 2139, which is thought to inhibit HBsAg release from hepatocytes and interact with hepatitis delta antigen. This review updates the epidemiology, virology and management of HDV infection.