HBeAg-positive hepatitis delta: virological patterns and clinical long-term outcome

Prevalence, characteristics, and virologic correlations of hepatitis delta (D) among patients with hepatitis B surface antigen in Mongolia

Clinical and biochemical features of hepatitis delta virus (HDV) infections in Mongolia remain largely unknown. We aimed to investigate the clinical characteristics of HDV patients in Mongolia using several markers. The 143 hepatitis B surface antigen (HBsAg)-positive patients were divided into 122 HDV-positive and 21 HDV-negative patients by HDV RNA positivity. Subgroup analysis was performed between hepatitis B e antigen (HBeAg)-positive and -negative HDV-positive patients. Liver function, quantitative HBsAg (qHBsAg), anti-HDV Immunoglobulin (Ig) M, Mac-2 binding protein glycosylation isomer (M2BPGi), hepatitis B virus (HBV) DNA level, and HDV RNA level were tested. HDV RNA was positive in 85.3% (122/143) of patients showing anti-HDV IgG. Liver disease activity was higher in HDV-positive patients than in HDV-negative patients. The HDV-positive group included a higher proportion of patients with high qHBsAg and M2BPGi levels (p < 0.001). The positivity rate for anti-HDV IgM was significantly higher in the HDV-positive group (p < 0.001). HDV RNA levels showed an inverse correlation with qHBsAg levels in HBeAg-positive-HDV-positive patients (r = -0.49, p = 0.034), and a positive correlation with qHBsAg levels in HBeAg-negative patients (r = 0.35, p < 0.001). Hepatitis B virus (HBV) DNA and HDV RNA levels did not show any correlation. M2BPGi levels likewise did not correlate with HDV RNA levels. A high positivity rate for HDV RNA was observed for HBV patients in Mongolia using the highly sensitive HDV RNA assay. The positivity rate for anti-HDV IgM was high in HDV RNA-positive patients. Severity of liver disease and M2BPGi levels were both high in the HDV RNA-positive group.

State of the Art: Test all for Anti-Hepatitis D Virus and Reflex to Hepatitis D Virus RNA Polymerase Chain Reaction Quantification

Diagnosis of HDV exposure is based on clinical assays of anti-hepatitis D antibody and current infection with hepatitis D RNA PCR. The role of hepatitis D antigen testing is not yet defined. RT-qPCR is the gold standard for measuring HDV RNA viral load, which is used to assess response to the treatment of HDV infection. Gaps in testing include poor sensitivity of antigen testing and quantitative HDV RNA accuracy can be affected by the genotypic variability of the virus and variation in laboratory techniques. There is also a limitation in HDV testing due to access, cost, and limited knowledge of testing indications. Droplet digital PCR promises to be a more accurate method to quantify HDV RNA. Also, the recent development of a rapid HDV detection test could prove useful in resource-limited areas.

HDV RNA assays: Performance characteristics, clinical utility, and challenges

Coinfection with HBV and HDV results in hepatitis D, the most severe form of chronic viral hepatitis, frequently leading to liver decompensation and HCC. Pegylated interferon alpha, the only treatment option for chronic hepatitis D for many years, has limited efficacy. New treatments are in advanced clinical development, with one recent approval. Diagnosis and antiviral treatment response monitoring are based on detection and quantification of HDV RNA. However, the development of reliable HDV RNA assays is challenged by viral heterogeneity (at least 8 different genotypes and several subgenotypes), intrahost viral diversity, rapid viral evolution, and distinct secondary structure features of HDV RNA. Different RNA extraction methodologies, primer/probe design for nucleic acid tests, lack of automation, and overall dearth of standardization across testing laboratories contribute to substantial variability in performance characteristics of research-based and commercial HDV RNA assays. A World Health Organization (WHO) standard for HDV RNA, available for about 10 years, has been used by many laboratories to determine the limit of detection of their assays and facilitates comparisons of RNA levels across study centers. Here we review challenges for robust pan genotype HDV RNA quantification, discuss particular clinical needs and the importance of reliable HDV RNA quantification in the context of drug development and patient monitoring. We summarize distinct technical features and performance characteristics of available HDV RNA assays. Finally, we provide considerations for the use of HDV RNA assays in the context of drug development and patient monitoring.

Cellular Factors Involved in the Hepatitis D Virus Life Cycle

Hepatitis D virus (HDV) is a defective RNA virus with a negative-strand RNA genome encompassing less than 1700 nucleotides. The HDV genome encodes only for one protein, the hepatitis delta antigen (HDAg), which exists in two forms acting as nucleoproteins. HDV depends on the envelope proteins of the hepatitis B virus as a helper virus for packaging its ribonucleoprotein complex (RNP). HDV is considered the causative agent for the most severe form of viral hepatitis leading to liver fibrosis/cirrhosis and hepatocellular carcinoma. Many steps of the life cycle of HDV are still enigmatic. This review gives an overview of the complete life cycle of HDV and identifies gaps in knowledge. The focus is on the description of cellular factors being involved in the life cycle of HDV and the deregulation of cellular pathways by HDV with respect to their relevance for viral replication, morphogenesis and HDV-associated pathogenesis. Moreover, recent progress in antiviral strategies targeting cellular structures is summarized in this article.

Diagnosis of HDV: From virology to non-invasive markers of fibrosis

Hepatitis D viral infection in humans is a disease that requires the establishment of hepatitis B, relying on hepatitis B surface Ag and host cellular machinery to replicate and propagate the infection. Since its discovery in 1977, substantial progress has been made to better understand the hepatitis D viral life cycle, pathogenesis and modes of transmission along with expanding on clinical knowledge related to prevention, diagnosis, monitoring and treatment. The availability of serologic diagnostic assays for hepatitis D infection has evolved over time with current widespread availability, improved detection and standardized reporting. With human migration, the epidemiology of hepatitis D infection has changed over time. Thus, the ability to use diagnostic assays remains essential to monitor the global impact of hepatitis D infection. Separately, while liver biopsy remains the gold standard for the staging of this rapidly progressive and severe form of chronic viral hepatitis, there is an unmet need for clinical monitoring of chronic hepatitis D infection for management of progressive disease. Thus, exploration of the utility of non-invasive fibrosis markers in hepatitis D is ongoing. In this review, we discuss the virology, the evolution of diagnostics and the development of non-invasive markers for the detection and monitoring of fibrosis in patients with hepatitis D infection.

Treatment endpoints for chronic hepatitis D

Management of chronic hepatitis D (CHD) has entered a new era. In this new era, the virus entry inhibitor bulevirtide has received conditional approval as a treatment for compensated CHD. Three phase 3 studies with two new compounds are ongoing for the treatment of CHD. In this context, surrogate markers of treatment efficacy have been well defined for chronic hepatitis B (CHB) (7) and chronic hepatitis C (8) but not for CHD. The aim of this review is to give a perspective on treatment endpoints in CHD. For this, we took guidance from CHB studies and tried to make suggestions which differed according to finite versus prolonged treatment durations and also took into account the different characteristics of the new compounds.

Natural history of untreated HDV patients: Always a progressive disease?

A severe course has been described in early studies on chronic hepatitis D (CHD), with faster pace towards liver cirrhosis with subsequent high liver-related morbidity and mortality in the majority of patients. Earlier studies have included risk groups as people using intravenous drugs (PWID) or those with multiple co-morbidities. During the last decade, the epidemiological landscape of CHD has changed with domestic cases decreasing while increasing cases of CHD consisting of younger persons immigrating from endemic regions to low-endemic regions. Recently, further insights into the spectrum of the disease with an indolent disease course in a substantial proportion of persons with CHD have been gained. At diagnosis, ≥30%-50% had already established liver cirrhosis. Older age, liver cirrhosis, co-infection with HIV and lack of interferon (IFN) therapy are the main predictors of worse clinical outcome. The newly introduced and upcoming antivirals against CHD are highly anticipated, considering the historically low virological response rates to antiviral therapy. Further knowledge is needed to fully comprehend the natural course and the spectrum of this severe form of viral hepatitis. This is also to be able to evaluate the long-term effects of the new antivirals on disease progression.

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.

Non-invasive fibrosis markers for assessment of liver fibrosis in chronic hepatitis delta

Assessment of liver fibrosis by non-invasive means is clinically important. Studies in chronic hepatitis delta (CHD) are scarce. We evaluated the performance of eight serum fibrosis markers [fibrosis-4 score (FIB-4), aspartate aminotransferase (AST) to alanine aminotransferase (ALT) ratio (AAR), age-platelet index (API), AST-to platelet-ratio-index (APRI), Goteborg University Cirrhosis Index (GUCI), Lok index, cirrhosis discriminant score (CDS) and Hui score] in CHD and chronic hepatitis B (CHB). Liver stiffness was assessed by transient elastography (TE) in CHD. The ability of fibrosis markers to detect significant fibrosis and cirrhosis were evaluated in 202 CHB and 108 CHD patients using published and new cut-offs through receiver operating characteristics (ROC) analysis. The latter was also applied to obtain cut-offs for TE. APRI, Fib-4, API and Hui score were assessed for significant fibrosis, and APRI, GUCI, Lok index, CDS and AAR for cirrhosis determination. Fibrosis markers displayed weak performance in CHB for significant fibrosis with area under ROC (AUROC) curves between 0.62 and 0.71. They did slightly better for CHD. TE displayed an AUROC of 0.92 and performed better than serum fibrosis markers (p < 0.05 for fibrosis markers). For cirrhosis determination, CDS and Lok Index displayed an AUROC of 088 and 0.89 in CHB and GUCI, Lok index and APRI displayed AUROCs around 0.90 in CHD. TE displayed the best AUROC (0.95). Hence TE is superior to serum fibrosis markers for diagnosing significant liver fibrosis and cirrhosis. GUCI, Lok index and APRI displayed a reasonable performance in CHD, which needs further confirmation.

Clinical trials in hepatitis D virus: Measuring success

Chronic hepatitis D infection results in the most severe form of chronic viral hepatitis but currently lacks effective treatment options. Therapy with pegylated interferon alpha is recommended for finite treatment duration by major liver societies. Still, it is plagued by low rates of sustained virologic response (SVR) and frequent relapses even if SVR is achieved. Recently, a wave of investigational therapies has come under evaluation, including bulevirtide, lonafarnib, pegylated interferon lambda, and REP-2139 creating excitement with this viral infection. However, there has been significant variability in the endpoints used to evaluate these therapeutics. One of the recently introduced endpoints is characterized by a decline in HDV RNA by 2 logs, with or without achieving an undetectable serum hepatitis D virus (HDV) RNA, as a marker of virologic response. Furthermore, this measure has been combined with alanine aminotransferase normalization, also known as a biochemical response, to formulate the primary endpoint of several late-stage studies. Per recent guidance by the US Food and Drug Administration, these should be surrogate endpoints that will ultimately portend long-term clinical benefits. These clinical benefits may include reducing the risk of progression to cirrhosis, hepatic decompensation, hepatocellular carcinoma, liver transplantation, and mortality. However, the optimal way to measure success in HDV clinical trials remains unknown and will continue to evolve.

Immune Mechanisms Underlying Hepatitis B Surface Antigen Seroclearance in Chronic Hepatitis B Patients With Viral Coinfection

It is considered that chronic hepatitis B patients have obtained functional cure if they get hepatitis B surface antigen (HBsAg) seroclearance after treatment. Serum HBsAg is produced by cccDNA that is extremely difficult to clear and dslDNA that is integrated with host chromosome. High HBsAg serum level leads to failure of host immune system, which makes it unable to produce effective antiviral response required for HBsAg seroclerance. Therefore, it is very difficult to achieve functional cure, and fewer than 1% of chronic hepatitis B patients are cured with antiviral treatment annually. Some chronic hepatitis B patients are coinfected with other chronic viral infections, such as HIV, HCV and HDV, which makes more difficult to cure. However, it is found that the probability of obtaining HBsAg seroclearance in patients with coinfection is higher than that in patients with HBV monoinfection, especially in patients with HBV/HIV coinfection who have an up to 36% of HBsAg 5-year-seroclerance rate. The mechanism of this interesting phenomenon is related to the functional reconstruction of immune system after antiretroviral therapy (ART). The quantity increase and function recovery of HBV specific T cells and B cells, and the higher level of cytokines and chemokines such as IP-10, GM-CSF, promote HBsAg seroclearance. This review summarizes recent studies on the immune factors that have influence on HBsAg seroconversion in the chronic hepatitis B patients with viral coinfection, which might provide new insights for the development of therapeutic approaches to partially restore the specific immune response to HBV and other viruses.

Review article: emerging insights into the immunopathology, clinical and therapeutic aspects of hepatitis delta virus

BACKGROUND

Hepatitis delta virus (HDV), which causes the most severe form of viral hepatitis, is an obligated hepatitis B (HBV) satellite virus that can either infect naïve subjects simultaneously with HBV (co-infection), or chronically infect HBV carriers (super-infection). An estimated 12 million people are infected by HDV worldwide.

AIMS

To summarise the most relevant aspects of the molecular biology of HDV, and to discuss the latest understanding of the induced pathology, interactions with the immune system, as well as both approved and investigational treatment options.

METHODS

References for this review were identified through searches of PubMed with the terms "HDV" "viral hepatitis" "co-infection" and "super-infection," published between 1980 and October 2021 RESULTS: The limited access to the HDV-infected liver has hampered the investigation of the intrahepatic compartment and our understanding of the mechanisms of HDV pathogenesis. In the absence of standardised and sensitive diagnostic tools, HDV is often underdiagnosed and owing to its strong dependence on host cellular factors, the development of direct antiviral agents has been challenging. New therapeutic agents targeting different steps of the viral cycle have recently been investigated, among which bulevirtide (which was conditionally approved by EMA in July 2020) and lonafarnib; both drugs having received orphan drug designation from both the EMA and FDA.

CONCLUSIONS

The HBV cure programme potentially offers a unique opportunity to enhance HDV treatment strategies. In addition, a more comprehensive analysis of the intrahepatic compartment is mandated to better understand any liver-confined interaction of HDV with the host immune system.

Poor clinical and virological outcome of nucleos(t)ide analogue monotherapy in HBV/HDV co-infected patients

Co-infection of Hepatitis B (HBV) and Delta viruses (HDV) represent the most severe form of viral hepatitis. While treatment with pegylated Interferon alpha (PEG-IFNα) is well established, therapy with nucleoside or nucleotide analogues (NA) has been a matter of debate. We aimed to investigate the role of NA treatment in a well-defined single centre cohort.In a retrospective approach, we observed 53 HDV RNA positive and/or anti-HDV-positive patients recruited at a German referral centre between 2000 and 2019. Patients were followed for at least 3 months (mean time of follow up: 4.6 years; range: 0.2-14.1 years). Patients who had liver transplantation or hepatocellular carcinoma at the time of presentation were excluded. 43% (n = 23) were treated with NA, 43% (n = 23) received IFNα-based therapies and 13% (n = 7) were untreated.Liver cirrhosis was already present in 53% (28/53) of patients at first presentation. During follow-up, liver-related endpoints developed in 44% of all patients (n = 23). NA-treatment was associated with a significantly worse clinical outcome (P = .01; odds ratio [OR] = 4.92; CI = 1.51-16.01) compared to both, untreated (P = .38; OR = 0.46; CI = 0.80-2.61) and IFNα-based-treated patients (P = .04; OR = 0.29; CI = 0.89-0.94) in univariate logistic regression analysis. HBsAg levels declined by more than 50% during NA-based therapy in only 7 cases (7/23; mean time: 3.6 years; range: 0.8-8.5 years) and during IFNα-based therapy in 14 cases (14/23; mean time: 2.8 years, range 0.7-8.5 years). HDV RNA became undetectable during follow up in 30% of patients receiving NA alone (7/23; mean time: 5.0 years; range: 0.6-13.5 years), in 35% of patients receiving IFNα-based therapy (8/23; mean time: 2.9 years, range: 0.3-7.6 years).The effect of NA in patients with HBV/HDV co-infection is limited. Treatment with NA was associated with a higher likelihood of clinical disease progression. Interferon alpha therapy was beneficial in reducing liver complications and improves long-term outcome.

The changing context of hepatitis D

The global epidemiology of hepatitis D is changing with the widespread implementation of vaccination against hepatitis B. In high-income countries that achieved optimal control of HBV, the epidemiology of hepatitis D is dual, consisting of an ageing cohort of domestic patients with advanced liver fibrosis who represent the end stage of the natural history of HDV, and of a younger generation of immigrants from endemic countries who account for the majority of new infections. As observed in Europe in the 1980s, the distinctive clinical characteristic of chronic hepatitis D in endemic countries is the accelerated progression to cirrhosis and hepatocellular carcinoma. Despite some recent progress, the therapeutic management of HDV remains unsatisfactory, as most patients are not cured of HDV with currently available medicines. This review article describes the current epidemiology and clinical features of chronic hepatitis D, based on the literature published in the last 10 years.

Experimental Drugs for the Treatment of Hepatitis D

Chronic hepatitis D virus infection is the most severe form of viral hepatitis. Antiviral treatment is urgently needed to prevent patients from developing end stage liver disease or hepatocellular carcinoma. Treatment options were limited to off-label use of pegylated interferon alfa until conditional approval of bulevirtide by the EMA (European Medicines Agency) in July 2020. However, several other antiviral compounds are currently investigated and represent promising agents for the treatment of chronic HDV infection.

Transaminase Elevations during Treatment of Chronic Hepatitis B Infection: Safety Considerations and Role in Achieving Functional Cure

While current therapies for chronic HBV infection work well to control viremia and stop the progression of liver disease, the preferred outcome of therapy is the restoration of immune control of HBV infection, allowing therapy to be removed while maintaining effective suppression of infection and reversal of liver damage. This “functional cure” of chronic HBV infection is characterized by the absence of detectable viremia (HBV DNA) and antigenemia (HBsAg) and normal liver function and is the goal of new therapies in development. Functional cure requires removal of the ability of infected cells in the liver to produce the hepatitis B surface antigen. The increased observation of transaminase elevations with new therapies makes understanding the safety and therapeutic impact of these flares an increasingly important issue. This review examines the factors driving the appearance of transaminase elevations during therapy of chronic HBV infection and the interplay of these factors in assessing the safety and beneficial nature of these flares.

Serial serologic changes of hepatitis D virus in chronic hepatitis B patients receiving nucleos(t)ides analogues therapy

BACKGROUND AND AIM

The serial serologic changes of hepatitis D virus (HDV) infection among chronic hepatitis B virus (HBV) infected patients who received oral nucleotide/nucleoside analogues are elusive.

METHODS

Serum anti-HDV and HDV RNA among chronic hepatitis B (CHB) patients were tested at the time of initiating anti-HBV therapy and subsequently during the follow-up period.

RESULTS

The seropositive rate of anti-HDV and HDV RNA among 2850 CHB patients, was 2.7% and 0.9%, respectively. Factors associated with anti-HDV seropositivity were platelet counts (odds ratio [OR]/95% confidence intervals [CI]: 0.995/0.992-0.999; P = 0.006), HBV DNA levels (OR/CI: 0.81/0.70-0.94; P = 0.005), and hepatitis B e-antigen (HBeAg) seropositivity (OR/CI: 0.22/0.05-0.95; P = 0.04). The only factor associated with HDV RNA positivity among anti-HDV seropositive patients was age (OR/CI: 0.95/0.90-1.00; P = 0.03). The spontaneous clearance rate of serum anti-HDV antibody was 3.0 per 100 person-years with a median follow-up period of 3.5 years (range 2-12 years), whereas the seroclearance rate of HDV RNA was 4.3 per 100 person-years among anti-HDV seropositive patients after a median follow-up period of 6.0 years (range 2-11 years). A baseline anti-HDV titer < 0.5 cut-off index was the only factor predictive of anti-HDV seroclearance (hazard ratio [HR]/CI: 30.11/3.73-242.85; P = 0.001).

CONCLUSIONS

HDV infection was not common among patients treated for HBV in Taiwan. Seroclearance of anti-HDV and HDV RNA did occur over time, albeit the chance is rare.

Molecular epidemiology of Hepatitis B virus, Hepatitis C virus, and Hepatitis D virus in general population of Afghanistan

BACKGROUND/AIMS

This study gives a clue about genotypes, subgenotypes and subtypes of HBV, HCV and HDV viruses in general population of Afghanistan.

MATERIALS AND METHODS

A total of 234 HBsAg, 44 anti-HCV and 5 Anti-Delta positive patients belong to 25-70 age group were obtained through a rapid screening test among 5898 residents of Afghanistan. After quantifying viral load, genotyping of 61 HBV, 29 HCV and 1 HDV samples were accomplished by sequencing of a segment of the HBV Pre S, HCV NS5B, and HDV Delta antigen regions respectively. Clinically important variants of the HBV polymerase gene, the "a" determinant of HBsAg, HCV NS5B and NS3 regions were assessed.

RESULTS

All HBV isolates were dispersed throughout the genotype D branch and ayw2 was the only subtypes found. The anti-HDV prevalence among HBsAg positive individuals was 2.2% and the single HDV sample, belonged to HDV genotype I. Analysis of HCV isolates revealed subtype HCV-1b in 75.86%, HCV-3a in 20.69% and HCV-3b in 3.44% patients. The observed mutant variants in the MHR of HBsAg were Y100 15%, Q101 5%, G102 15%, T115 45%, P120 5%, T131 5%. Likewise, S213T 10%, Q215P 5% and N248H 100% mutations were detected in the HBV polymerase region. C316N mutation was prevalent in 72.7% of HCV 1b participants.

CONCLUSION

Genotypic variation in Afghan patients is in line with the ones existing in neighboring countries and regions. HBV genotypes D1, subtype ayw2, HDV RNA type I, and HCV RNA genotype 1b are likely to be dominant in Afghan patients.

Effect of HBV-HDV co-infection on HBV-HCC co-recurrence in patients undergoing living donor liver transplantation

PURPOSE

To evaluate the effect of hepatitis D virus (HDV) on hepatitis B virus-hepatocellular carcinoma (HBV-HCC) co-recurrence in patients undergoing living donor liver transplantation (LDLT) for HBV alone or HBV-HDV coinfection.

METHODS

Between 2002 and 2019, 254 HBV-HCC patients underwent LDLT. The patients were divided into two groups after the application of the exclusion criteria: HBV-HCC (Group B; n = 163) and HBV-HDV-HCC (Group D; n = 31). First, the B and D groups were compared in terms of demographic and clinical parameters. Second, patients with (n = 16) and without (n = 178) post-transplant HBV-HCC co-recurrences were grouped and compared in terms of the same parameters.

RESULTS

Although the risk of HBV-HCC co-recurrence in group D was 4.99-fold higher than in group B, the risk of HBV recurrence alone in group D was 12.5-fold lower than in group B. The AFP (OR = 4.4), Milan criteria (beyond; OR = 18.8), and HDV (OR = 8.1) were identified as the independent risk factors affecting post-transplant HBV-HCC co-recurrence. The Milan criteria (OR = 2.1) and HBV-HCC co-recurrence (OR = 10.9) were identified as the risk factors affecting post-transplant mortality. HBV-HCC co-recurrence developed in 26.5% of patients in Group B and 100% in Group D (OR = 40; p = 0.001). HCC recurrence alone developed in 10% of patients without HBV recurrence in group B and 0% of patients without HBV recurrence in group D (OR = 5.7).

CONCLUSION

This study showed that the risk of HBV recurrence alone was reduced by 12.5-fold in the presence of HDV; however, the HCC recurrence occurred in all patients with HDV when HBV recurrence developed.

Molecular epidemiology and clinical characteristics of hepatitis delta virus (HDV) infected patients with elevated transaminases in Shanghai, China

BACKGROUND

Patients coinfected with HBV and hepatitis D virus (HDV) have a greater risk of HCC and cirrhosis. The current study was undertaken to assess HDV genotype distribution and determine clinical characteristics of hepatitis delta virus (HDV) among HBsAg positive individuals in Shanghai.

METHOD

This retrospective study involved 225 serum samples from HBsAg positive hospitalized patients from October 2010 to April 2013. HDV-specific RT-nested PCR was used to amplify HDV RNA. HDV genotypes were characterized by Next-generation sequencing (NGS), followed by phylogenetic analyses. HDV/HBV co-infected patients and HBV mono-infected patients were compared clinically and virologically.

RESULTS

Out of the 225 HBsAg-positive serum samples with elevated transaminases, HDV-RNA was identified in 11 (4.9%) patients. The HBV loads in the HDV positive group were significantly lower than the HDV negative HBV-infected patients. The aminotransferase enzymes were significantly higher in HDV/HBV co-infected compared to HDV negative patients (P < 0.05). Phylogenetic analyses indicated that HDV-2 genotype being the predominant genotype, other HDV genotypes were not observed. HDV/HBV patients were significantly associated with a rather unfavourable clinical outcome.

CONCLUSION

In summary, the prevalence of HDV infection in patients with elevated transaminases is not low and the predominance of HDV genotype 2 infection in Shanghai. This finding helps us to better understand the correlation of HDV/HBV co-infection. Moreover, Next-generation sequencing (NGS) technologies provide a rapid, precise method for generating HDV genomes to define infecting genotypes.

The Delta-4 fibrosis score (D4FS): A novel fibrosis score in chronic hepatitis D

BACKGROUND

Chronic Hepatitis D virus (HDV) infection results in the most severe form of viral hepatitis with a rapid progression to cirrhosis. However, non-invasive fibrosis tests that can accurately predict cirrhosis have not been adequately validated. We aimed to develop a clinically useful non-invasive score that can accurately detect cirrhosis.

MATERIAL AND METHODS

Patients with chronic HDV diagnosed by liver histology or serum PCR were evaluated. Data regarding demographics, laboratory, imaging, vibration-controlled transient elastography (VCTE), and liver biopsy were collected. The total cohort was randomized into a training and validation cohort. The training cohort was used to develop a novel score, the Delta-4 fibrosis score (D4FS) which was then compared to other non-invasive tests in the validation cohort by area under receiver operating characteristics (AUROC).

RESULTS

77 patients with chronic HDV were evaluated: mean age 42.6 (SD:11.1) years, 59.7% male, and 57.1% Asian. The total cohort was then separated into a training (n = 45) and validation (n = 32) cohort with no significant differences in terms of clinical characteristics between the two. From the training cohort, the D4FS was derived from variables of statistical and clinical interest (gamma-glutamyl transpeptidase (GGT), platelet count, alanine aminotransferase (ALT), and liver stiffness measurement (LSM)). The D4FS demonstrated the best AUROC in the validation cohort (0.94) followed by VCTE (0.90), FIB-4 (0.86), APRI (0.81), and AAR (0.71).

DISCUSSION

The D4FS is a clinically useful non-invasive fibrosis score that can accurately detect cirrhosis in patients with chronic HDV infection. Further studies should be performed to further validate clinical utility.

Hepatitis D infection: from initial discovery to current investigational therapies

Hepatitis D is the most severe form of viral hepatitis associated with a more rapid progression to cirrhosis and an increased risk of hepatocellular carcinoma and mortality compared with hepatitis B mono-infection. Although once thought of as a disappearing disease, hepatitis D is now becoming recognized as a serious worldwide issue due to improvement in diagnostic testing and immigration from endemic countries. Despite these concerns, there is currently only one accepted medical therapy (pegylated-interferon-α) for the treatment of hepatitis D with less than desirable efficacy and significant side effects. Due to these reasons, many patients never undergo treatment. However, increasing knowledge about the virus and its life cycle has led to the clinical development of multiple promising new therapies that hope to alter the natural history of this disease and improve patient outcome. In this article, we will review the literature from discovery to the current investigational therapies.

Quantification of serum markers of hepatitis B (HBV) and Delta virus (HDV) infections in patients with chronic HDV infection

The interplay between hepatitis B (HBV) and delta (HDV) viruses is complex and not always characterized during chronic HDV infection. We assessed the clinical usefulness of new quantitative assays for HBV and HDV serum markers in a retrospective cross-sectional study. Sera obtained from 122 HDV genotype 1 and HBV genotype D coinfected, anti-HIV-negative patients (71 males; median age 49.8 [21.7-66.9] years), recruited consecutively in two geographical areas (Italy 69 patients, Romania 53 patients) with different HBV and HDV epidemiology, were tested for HBsAg, HBV-DNA, HBcrAg, total anti-HBc, HDV-RNA, IgM and total anti-HDV using quantitative assays. Cirrhosis, which showed comparable prevalence in the two cohorts, was diagnosed in 97 of 122 (79.5%) patients. At multivariate analysis, cirrhosis was associated with lower total anti-HBc/IgM anti-HDV ratio (OR 0.990, 95% CI 0.981-0.999, P = .038), whereas disease activity was associated with higher total anti-HDV (OR 10.105, 95% CI 1.671-61.107, P = .012) and HDV-RNA levels (OR 2.366, 95% CI 1.456-3.844, P = .001). HDV-RNA serum levels showed a positive correlation with HBV-DNA (ρ = 0.276, P = .005), HBsAg (ρ = 0.404, P < .001) and HBcrAg (ρ = 0.332, P < .001). The combined quantitative profiling of HBV and HDV serum markers identifies specific patterns associated with activity and stage of chronic hepatitis D (CHD). HDV pathogenicity depends on the underlying active HBV infection in spite of the inhibition of its replication. HDV-RNA, IgM anti-HDV, total anti-HDV, total anti-HBc, HBsAg and HBcrAg serum levels qualify for prospective studies to predict progressive CHD and identify candidates to antiviral therapy.

Chronic Hepatitis B, C, and D

Chronic hepatitis B, C, and D virus infections contribute significantly to the morbidity and mortality of immunocompromised individuals. To contextualize discussion of these infections in immunocompromised patients, this paper provides an overview of aspects of infection in normal hosts. It then describes differences in disease, diagnostic testing, and therapeutic management observed in immunocompromised patients.

Prevalence and genotype distribution of hepatitis delta virus among chronic hepatitis B carriers in Central Vietnam

Hepatitis D virus (HDV) infection plays an important role in liver diseases. However, the molecular epidemiology and impact of HDV infection in chronic hepatitis B (CHB) remain uncertain in Vietnam. This cross-sectional study aimed to investigate the prevalence and genotype distribution of HDV among HBsAg-positive patients in Central Vietnam. 250 CHB patients were tested for HDV using newly established HDV-specific RT-PCR techniques. HDV genotypes were determined by direct sequencing. Of the 250 patients 25 (10%) had detectable copies of HDV viral RNA. HDV-2 was predominant (20/25; 80%) followed by HDV-1 (5/25; 20%). Proven HDV genotypes share the Asian nomenclature. Chronic hepatitis B patients with concomitant HDV-1 showed higher HBV loads as compared to HDV-2 infected patients [median log10 (HBV-DNA copies/ml): 8.5 vs. 4.4, P = 0.036]. Our findings indicate that HDV infection is highly prevalent and HDV-2 is predominant in Central Vietnam. The data will add new information to the management of HBsAg-positive patients in a highly HBV endemic region to in- or exclude HDV infection in terms of diagnostic and treatment options.

Antiviral treatment and liver-related complications in hepatitis delta

Hepatitis delta virus (HDV) is the most severe form of viral hepatitis. Pegylated interferon alfa (PEG-IFNα) is effective in only 25%-30% of patients and is associated with frequent side effects. The aim of this study was to analyze the clinical long-term outcome of hepatitis delta in relation to different antiviral treatment strategies. We studied 136 anti-HDV-positive patients who were followed for at least 6 months in a retrospective single-center cohort (mean time of follow-up, 5.2 years; range, 0.6-18.8). Liver cirrhosis was already present in 62 patients at first presentation. Twenty-nine percent of patients did not receive any antiviral treatment, 38% were treated with interferon alfa (IFNα)-based therapies, and 33% received nucleos(t)ide analogues (NAs) only. Clinical endpoints defined as hepatic decompensation (ascites, encephalopathy, and variceal bleeding), hepatocellular carcinoma, liver transplantation, and liver-related death developed in 55 patients (40%). Patients who received IFNα-based therapies developed clinical endpoints less frequently than those treated with NA (P = 0.02; HR, 4.0) or untreated patients (P = 0.05; HR, 2.2; 17%, 64%, and 44%), respectively, which was significant in both chi-square and Kaplan-Meier analysis. In addition, considering various clinical and virological parameters, IFNα therapy was independently associated with a more benign clinical long-term outcome in multivariate logistic regression analysis (P = 0.04; odds ratio, 0.25; 95% confidence interval, 0.07-0.9). Loss of HDV RNA during follow-up was more frequent in IFNα-treated patients and strongly linked with a lower likelihood to experience liver-related complications.

CONCLUSION

IFNα-based antiviral therapy of hepatitis delta was independently associated with a lower likelihood for clinical disease progression. Durable undetectability of HDV RNA is a valid surrogate endpoint in the treatment of hepatitis delta. (Hepatology 2017;65:414-425).

The role of quantitative hepatitis B surface antigen revisited

In the past 10years, there has been a lot of enthusiasm surrounding the use of serum hepatitis B surface antigen (HBsAg) quantification to predict disease activity and monitor treatment response in chronic hepatitis B. The measurement of HBsAg levels have been standardized in IU/ml, and nowadays it is almost a mandatory measurement due to the development of new antiviral treatments aiming at HBsAg seroclearance, i.e., functional cure of hepatitis B. Recently, there has been an improved understanding of the molecular virology of HBsAg, and particularly the relative roles of covalently closed circular DNA and integrated hepatitis B virus (HBV) DNA. This has shed new light on the interpretation of HBsAg levels in different phases of chronic hepatitis B. HBsAg level can assist the differentiation of immune tolerance and immune clearance in hepatitis B e antigen (HBeAg)-positive patients, and it can predict inactive disease and spontaneous HBsAg seroclearance in HBeAg-negative patients. The determination of HBsAg level is pivotal to individualize pegylated interferon (PegIFN) treatment; it is the key investigation to decide early termination of PegIFN among non-responders. Among patients treated by nucleos(t)ide analogues, responders tend to have dramatic reduction of HBsAg to low levels, which may be followed by HBsAg seroclearance. With newer data on combination treatment of PegIFN and nucleos(t)ide analogues as well as emerging new antiviral agents, HBsAg quantification is expected to become increasingly important to monitor and guide antiviral therapy for chronic hepatitis B.

Management of HBV and HBV/HDV-Associated Liver Cirrhosis

BACKGROUND

Chronic hepatitis B virus (HBV) infection and hepatitis delta virus (HDV) co-infection lead to liver cirrhosis, hepatic decompensation, and hepatocellular carcinoma (HCC).

METHODS

We review the current knowledge of the management of HBV mono-infection and HBV/HDV co-infection with a special emphasis on liver cirrhosis.

RESULTS

Treatment options for chronic hepatitis B are pegylated interferon (PEG-IFN) alfa and nucleos(t)ide analogues (NUC). PEG-IFN is a finite option to achieve hepatitis B surface antigen loss in compensated cirrhosis. However, this goal is rare. NUC are potent to achieve HBV DNA suppression but long-term treatment is mandatory in most cases. Long-term treatment with NUC can lead to reversion of liver cirrhosis, improve liver function, prevent liver transplantation, and reduces but does not eliminate the risk for development of HCC. Treatment options for hepatitis D are limited to PEG-IFN. Although late relapse is common, treatment with PEG-IFN reduces disease progression. However, new treatments are urgently needed for HDV infection.

CONCLUSION

Early treatment of chronic hepatitis B and D is important to prevent complications of cirrhosis. HCC surveillance remains important in patients with cirrhosis.

Hepatitis D and hepatocellular carcinoma

Hepatitis D virus (HDV) is a defective circular shape single stranded HDV RNA virus with two types of viral proteins, small and large hepatitis D antigens, surrounded by hepatitis B surface antigen. Superinfection with HDV in chronic hepatitis B is associated with a more threatening form of liver disease leading to rapid progression to cirrhosis. In spite of some controversy in the epidemiological studies, HDV infection does increase the risk of hepatocellular carcinoma (HCC) compared to hepatitis B virus (HBV) monoinfection. Hepatic decompensation, rather than development of HCC, is the first usual clinical endpoint during the course of HDV infection. Oxidative stress as a result of severe necroinflammation may progress to HCC. The large hepatitis D antigen is a regulator of various cellular functions and an activator of signal transducer and activator of transcription (STAT)3 and the nuclear factor kappa B pathway. Another proposed epigenetic mechanism by which HCC may form is the aberrant silencing of tumor suppressor genes by DNA Methyltransferases. HDV antigens have also been associated with increased histone H3 acetylation of the clusterin promoter. This enhances the expression of clusterin in infected cells, increasing cell survival potential. Any contribution of HBV DNA integration with chromosomes of infected hepatocytes is not clear at this stage. The targeted inhibition of STAT3 and cyclophilin, and augmentation of peroxisome proliferator-activated receptor γ have a potential therapeutic role in HCC.

Chronic HDV/HBV co-infection: predictors of disease stage---a case series of HDV-3 patients

BACKGROUND & AIMS

Chronic HDV/HBV co-infection is perhaps the most intriguing amongst all viral hepatitis. Only few studies focus deeply on this topic, particularly with patients infected with HDV-3. This study aimed to identify predictors of advanced disease, examining a cross-sectional data of 64 patients.

METHODS

Histological grading was used to characterize the disease stages and viral loads were tested as predictors of necroinflammatory activity and fibrosis.

RESULTS

We identified three HDV/HBV co-infection patterns: patients with predominant HDV replication (56.3%), patients with similar viral loads of both viruses (40.6%), and patients with predominant HBV replication (3.1%). Mean HDV-RNA showed a positive trend regarding inflammatory activity and grade of fibrosis. HDV viral load correlated positively with serum levels of liver enzymes and inversely with platelets count. HBV viral load showed no correlation with any of the above parameters. Advanced fibrosis was associated with age, splenomegaly, and HDV viral load of more than 2 log10. Multiple logistic regression confirmed the independent effect of HDV viral predominance. Advanced necroinflammatory activity was independently associated with HDV viral load and splenomegaly.

CONCLUSIONS

HDV may possibly play an important and direct role in the establishment of necroinflammatory activity and fibrosis. Data show an indigenous HDV genotype, HDV-3, similar to those described in the Amazon region.

Clinical presentation of hepatitis D in Pakistani children

BACKGROUND

There are limited data on hepatitis D in children. The aim of this study was to assess the clinical presentation of hepatitis D virus (HDV) infection in Pakistani children.

MATERIALS AND METHODS

All pediatric patients (age≤18 years) seen in the clinic with chronic HDV infection and detectable HDV RNA (n=48) were compared with consecutive hepatitis B virus (HBV) monoinfection patients (n=48). A total of 50 patients underwent liver biopsy: 28 in the HDV group and 22 in the HBV group.

RESULTS

There was a male preponderance (85.4%). Significant differences were noted in age (P=0.012), presence of cirrhosis (P=0.004), splenomegaly (P<0.001), esophageal varices (P=0.006), splenic varices (P=0.022), alanine aminotransferase, aspartate aminotransferase and γ-glutamyl transferase levels (P<0.001 each), platelet count (P=0.015), international normalized ratio (P<0.001), severity of inflammation on liver biopsy (P=0.007), and advanced fibrosis (P=0.016) in the two groups, indicating more severe disease in the HDV group. In the HDV group, six patients had normal ALT, of whom three were positive for hepatitis B e antigen (HBeAg) and HBV DNA. HBV DNA was detectable in 50% and HBeAg in 52% of the HDV patients. There were no differences in the severity of liver disease in HBeAg-reactive and HBeAg-nonreactive patients. Six patients with hepatitis D had decompensation at the time of presentation; five were HBV DNA positive and three had reactive HBeAg. Only one patient with HBV monoinfection had decompensation.

CONCLUSION

Children with HDV infection have more aggressive liver disease than HBV monoinfection irrespective of HBeAg status.

Role of immunohistochemistry for hepatitis D and hepatitis B virus in hepatitis delta

BACKGROUND & AIMS

Immunohistochemical assessment of liver tissue in chronic delta hepatitis (CDH) is underinvestigated. Aim of the study was (i) to assess variables associated with hepatitis D antigen (HDAg), hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg) staining in the liver.

METHODS

Demographic, biochemical and virologic data collected from the HIDIT 1 study were used. HBsAg, HBcAg and HDAg immunohistochemical (IHC) staining was semiquantitatively assessed.

RESULTS

Hepatitis D antigen immunohistochemical staining displayed positive correlations with age and alanine aminotransferase (ALT) and negative correlations with serum HBsAg (P = 0.01 for all). HBsAg IHC displayed a negative correlation with gamma glutamyl transferase and positive correlations with serum HBV DNA, serum HBsAg levels and HBeAg serology (P < 0.001, P = 0.02 and P = 0.007 respectively). HBcAg staining was mainly nuclear and displayed negative correlations with serum HBsAg and histologic activity (P = 0.002 and P = 0.02 respectively). Pegylated IFN based treatment led to a decline of all IHC markers, however, these markers had no impact on treatment outcome.

CONCLUSIONS

These data suggest an association of liver injury with HDAg expression in CDH whereas the negative correlation between HBcAg expression and liver injury and the overall nuclear localization of HBcAg suggest that HBcAg does not contribute to liver injury in CDH. HDV cases with high level of HBV replication, high serum HBsAg levels, HBeAg positivity, that are probably in the earlier stages of disease (low gamma-glutamyl transferase), had a more intense HBsAg staining profile. Overall, the data enforce the importance of HDAg and HBsAg in different phases of CDH infection.

Anti-HDV IgM as a marker of disease activity in hepatitis delta

Background

Hepatitis delta frequently leads to liver cirrhosis and hepatic decompensation. As treatment options are limited, there is a need for biomarkers to determine disease activity and to predict the risk of disease progression. We hypothesized that anti-HDV IgM could represent such a marker.

Methods

Samples of 120 HDV-infected patients recruited in an international multicenter treatment trial (HIDIT-2) were studied. Anti-HDV IgM testing was performed using ETI-DELTA-IGMK-2-assay (DiaSorin). In addition, fifty cytokines, chemokines and angiogenetic factors were measured using multiplex technology (Bio-Plex System). A second independent cohort of 78 patients was studied for the development of liver-related clinical endpoints (decompensation, HCC, liver transplantation or death; median follow up of 3.0 years, range 0.6–12).

Results

Anti-HDV IgM serum levels were negative in 18 (15%), low (OD<0.5) in 76 (63%), and high in 26 (22%) patients of the HIDIT-2 cohort. Anti-HDV IgM were significantly associated with histological inflammatory (p<0.01) and biochemical disease activity (ALT, AST p<0.01). HDV replication was independent from anti-HDV IgM, however, low HBV-DNA levels were observed in groups with higher anti-HDV IgM levels (p<0.01). While high IP-10 (CXCL10) levels were seen in greater groups of anti-HDV IgM levels, various other antiviral cytokines were negatively associated with anti-HDV IgM. Associations between anti-HDV IgM and ALT, AST, HBV-DNA were confirmed in the independent cohort. Clinical endpoints occurred in 26 anti-HDV IgM positive patients (39%) but in only one anti-HDV IgM negative individual (9%; p = 0.05).

Conclusions

Serum anti-HDV IgM is a robust, easy-to-apply and relatively cheap marker to determine disease activity in hepatitis delta which has prognostic implications. High anti-HDV IgM levels may indicate an activated interferon system but exhausted antiviral immunity.

Late HDV RNA relapse after peginterferon alpha-based therapy of chronic hepatitis delta

Interferon alpha is the only treatment option for hepatitis delta virus (HDV). Trials investigating the efficacy of pegylated interferon alpha (PEG-IFNa) showed HDV RNA negativity rates of 25-30% 24 weeks after therapy. However, the clinical and virological long-term outcome of HDV-infected patients treated with PEG-IFNa is unknown. We performed a retrospective-prospective follow-up of 77 patients treated for 48 weeks with either PEG-alfa-2a and adefovir (ADV) or either drug alone in the Hep-Net-International-Delta-Hepatitis-Intervention-Study 1 (HIDIT-1) trial. Long-term follow-up data were available for 58 out of 77 patients (75%) with a median time of follow-up of 4.5 (0.5-5.5) years and a median 3 visits per patient. Patients treated with ADV alone received retreatment with PEG-IFNa (48% versus 19%; P = 0.02) more often. Hepatitis B virus surface antigen (HBsAg) became negative in six PEG-IFNa-treated patients until the end of long-term follow-up (10%). Sixteen patients tested HDV RNA-negative 6 months after PEG-IFNa treatment who were entered in the long-term follow-up study. Out of these, nine individuals tested HDV RNA-positive at least once during further long-term follow-up, with seven patients being HDV RNA-positive at the most recent visit. Clinical endpoints (liver-related death, liver transplantation, hepatic decompensation, hepatocellular carcinoma) were observed in three PEG-IFNa-treated (8%) and three ADV-treated (14%) patients during posttreatment long-term follow-up with an overall annual event rate of 2.5% (4.9% in cirrhosis). Sequencing confirmed the reappearance of pretreatment virus strains in all cases.

CONCLUSION

Late HDV RNA relapses may occur after PEG-IFNa therapy of hepatitis delta and thus the term sustained virological response should be avoided in HDV infection. The annual posttreatment rate of clinical events in hepatitis delta patients eligible for PEG-IFNa therapy is about 2.5% and 4.9% in patients with cirrhosis.

High serum levels of HDV RNA are predictors of cirrhosis and liver cancer in patients with chronic hepatitis delta

Chronic infection with the hepatitis delta virus (HDV) is a risk factor for cirrhosis and hepatocellular carcinoma (HCC), but little is known whether the outcome of hepatitis is predicted by serum markers of HDV and hepatitis B virus (HBV) infection. The aim of the study was to investigate these correlations in 193 patients with chronic HDV infection who had been followed up for a median of 9.5 years (4.8–19.3). HDV-RNA was first measured by qualitative in-house nested RT-PCR and quantified by in-house real-time PCR. HDV RNA levels only appeared significantly associated to HCC (univariate analysis: OR 1.32, 95% CI 1.02–1.71; p = 0.037; multivariate analysis: OR 1.42, 95% CI 1.04–1.95; p = 0.03). In non-cirrhotics at first presentation (n = 105), HDV RNA levels were associated with progression to cirrhosis (univariate analysis: OR = 1.57, 95% CI 1.20–2.05, p<0.001; multivariate analysis: OR = 1.60, 95% CI 1.20–2.12, p = 0.007) and development of HCC (univariate analysis: OR = 1.66, 95% CI 1.04–2.65, p = 0.033; multivariate analysis: OR = 1.88, 95% CI 1.11–3.19, p = 0.019). ROC analysis showed that approximately 600,000 HDV RNA copies/mL was the optimal cut-off value in our cohort of patients for discriminating the development of cirrhosis. High levels of HDV viremia in non-cirrhotic patients are associated with a considerable likelihood of progression to cirrhosis and the development of HCC. Once cirrhosis has developed, the role of HDV replication as a predictor of a negative outcome lessens.

Prevalence of hepatitis d virus infection among patients with chronic hepatitis B attending birjand hepatitis clinic (East of iran) in 2012

BACKGROUND

Hepatitis delta virus (HDV) is a defective RNA virus dependent on Hepatitis B virus (HBV) infection for its replication and expression. All patients with HBV infection should be tested for the presence of HDV infection. It is estimated that approximately 5% of hepatitis B surface antigen (HbsAg) carriers in the world are HDV infected patients. HBV-HDV co-infection may lead to more severe acute disease and higher risks of fulminant hepatitis, cirrhosis, and hepatocellular carcinoma than those having HBV infection alone. Also, HBV infected patients with HDV super-infection have a higher rate of progression to chronic disease and serious complications.

OBJECTIVES

Our aim was to determine the prevalence of HDV infection among chronic hepatitis B (CHB) patients attending Birjand Hepatitis Clinic, East of Iran.

MATERIALS AND METHODS

A cross-sectional analytical study was conducted on 413 CHB patients in 2012. Serology test for anti-HDV was measured by ELISA in these patients. CHB patients had positive hepatitis B surface antigen for at least 6 months before the study entrance.

RESULTS

The mean age of CHB patients was 38.5± 11.9 years and 55.9% of them (231 patients) were male. There were 13 cases (3.1%) with HDV infection. There was no association between positive anti-HDV serology and factors such as age, gender, carrier state, liver enzymes, and positive hepatitis B e antigen (HBeAg) serology.

CONCLUSIONS

Although HDV had a low prevalence in our area, it is important for healthcare providers and policy makers to plan preventive strategies for HDV spread as well as HBV prevention programs among high risk population.

Hepatitis viruses (other than hepatitis B and C viruses) as causes of hepatocellular carcinoma: an update

Chronic hepatitis B and C virus infections are universally accepted as causes of hepatocellular carcinoma in humans. Hepatitis A and E viruses cause only acute self-limiting infections of the liver. Of the remaining hepatitis viruses - Delta hepatitis, hepatitis G (GB-C), TT and SEN - all have at some time been incriminated as causes of hepatocellular carcinoma. Delta hepatitis virus requires helper functions from hepatitis B virus to become invasive. Chronic Delta/hepatitis B viral co-infection runs a more severe course than that resulting from chronic hepatitis B virus infection alone, with progression to cirrhosis being more likely and more rapid. A substantial majority of the early studies did not find an increased incidence of hepatocellular carcinoma in co-infected individuals. But more recently, an increased incidence of the tumour has been recorded more often than no increase. Further studies are needed to draw a firm conclusion with regard to the hepatocarcinogenic effect of dual Delta/hepatitis B virus co-infection. With one exception, no published study (of 13) has incriminated chronic infection with hepatitis G virus as a cause of hepatocellular carcinoma. The dissenting study, published in 1999, was the only one performed in the United States. Fewer studies of the hepatocarcinogenic effect of TT virus have been performed. Apart from one study, published in 1999, no convincing evidence is available that supports a causal role for TT virus in hepatocarcinogenesis. The exception was in Japanese patients with high hepatitis C viral loads but independent of chronic hepatitis C virus infection. No evidence has been produced to indicate that SEN virus causes hepatocellular carcinoma.

Treatment options for hepatitis delta virus infection

The hepatitis D virus (HDV), the smallest virus known to infect man, causes the most severe form of chronic viral hepatitis, hepatitis delta. It is estimated that about 15 to 20 million people are suffering from chronic HDV infection. HDV is a defective satellite virus depending on the hepatitis B surface antigen (HBsAg) for transmission. Chronic hepatitis delta is associated with a rapid progression of liver fibrosis and a high prevalence of liver cirrhosis, even in younger patients. Immunization against hepatitis B virus (HBV) protects from HDV infection, but there is no specific vaccine against HDV available for HBsAg-positive individuals. Treatment options for hepatitis delta patients are limited. So far, only interferon-alpha has shown an antiviral efficacy against HDV. Recent trials showed sustained virological response rates concerning HDV in 25 %-30 % of patients treated with pegylated interferons. HDV is dominant over HBV in the majority of cases, but HBV DNA-positive subjects should be treated with HBV polymerase inhibitors. Combination therapy of pegylated interferon-alpha and adefovir showed a more pronounced HBsAg decline, but the exact role of combination therapies in hepatitis delta requires further investigation. Alternative future treatment strategies may include prenylation inhibitors and HBV entry inhibitors, which are in early clinical development.