Treatment of hepatitis D

Leveraging stem cells to combat hepatitis: a comprehensive review of recent studies

Hepatitis is a significant global public health concern, with viral infections being the most common cause of liver inflammation. Antiviral medications are the primary treatments used to suppress the virus and prevent liver damage. However, the high cost of these drugs and the lack of awareness and stigma surrounding the disease create challenges in managing hepatitis. Stem cell therapy has arisen as a promising therapeutic strategy for hepatitis by virtue of its regenerative and immunomodulatory characteristics. Stem cells have the exceptional capacity to develop into numerous cell types and facilitate tissue regeneration, rendering them a highly promising therapeutic avenue for hepatitis. In animal models, stem cell therapy has demonstrated worthy results by reducing liver inflammation and improving liver function. Furthermore, clinical trials have been undertaken to assess the safety and effectiveness of stem cell therapy in individuals with hepatitis. This review aims to explore the involvement of stem cells in treating hepatitis and highlight the findings from studies conducted on both animals and humans. The objective of this review is to primarily concentrate on the ongoing and future clinical trials that assess the application of stem cell therapy in the context of hepatitis, including the transplantation of autologous bone marrow-derived stem cells, human induced pluripotent stem cells, and other mesenchymal stem cells. In addition, this review will explore the potential merits and constraints linked to stem cell therapy for hepatitis, as well as its prospective implications in the management of this disease.

Non-organ-specific autoantibodies with unspecific patterns are a frequent para-infectious feature of chronic hepatitis D

Infections with hepatotropic viruses are associated with various immune phenomena. Hepatitis D virus (HDV) causes the most severe form of viral hepatitis. However, few recent data are available on non-disease-specific and non-organ-specific antibody (NOSA) titers and immunoglobulin G (IgG) levels in chronic hepatitis D (CHD) patients. Here, we examined the NOSA titers and IgG levels of 40 patients with CHD and different disease courses and compared them to 70 patients with chronic hepatitis B (CHB) infection. 43% of CHD patients had previously undergone treatment with pegylated interferon-α (IFN-α). The antibody display of 46 untreated patients diagnosed with autoimmune hepatitis (AIH) was used as a reference. The frequency of elevated NOSA titers (CHD 69% vs. CHB 43%, p < 0.01), and the median IgG levels (CHD 16.9 g/L vs. CHB 12.7 g/L, p < 0.01) were significantly higher in CHD patients than in patients with CHB, and highest in patients with AIH (96%, 19.5 g/L). Also, the antinuclear antibody pattern was homogeneous in many patients with AIH and unspecific in patients with viral hepatitis. Additionally, f-actin autoantibodies were only detectable in patients with AIH (39% of SMA). In CHD patients, IgG levels correlated with higher HDV viral loads, transaminases, and liver stiffness values. IgG levels and NOSA were similar in CHD patients irrespective of a previous IFN-α treatment. In summary, autoantibodies with an unspecific pattern are frequently detected in CHD patients with unclear clinical relevance.

Hepatitis D virus: Improving virological knowledge to develop new treatments

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

A Review of HDV Infection

Hepatitis D is the most severe viral hepatitis. Hepatitis D virus (HDV) has a very small RNA genome with unique biological properties. It requires for infection the presence of hepatitis B virus (HBV) and is transmitted parenterally, mainly by superinfection of HBsAg carriers who then develop chronic hepatitis D. HDV has been brought under control in high-income countries by the implementation of HBV vaccination, and the clinical pattern has changed to a chronic hepatitis D seen in ageing patients with advanced fibrotic disease; the disease remains a major health concern in developing countries of Africa and Asia. Every HBsAg-positive subject should be tested for HDV serum markers by reflex testing, independently of clinical status. Vaccination against HBV provides the best prophylaxis against hepatitis D. The only therapy available so far has been the poorly performing Interferon alfa; however, several new and promising therapeutic approaches are under study.

Viral hepatitis: A narrative review of hepatitis A–E

Viral hepatitis continues to be a major health concern leading to hepatic decompensation ranging from acute hepatitis to cirrhosis and hepatocellular carcinoma. The hepatic and extrahepatic manifestations are not only debilitating but also associated with a significant economic burden. Over the last two decades, the field of virology has made significant breakthroughs leading to a better understanding of the pathophysiology of viral hepatitis, which in turn has led to new therapeutic options. The advent of direct-acting antiviral agents changed the landscape of hepatitis C virus (HCV) therapy, and new drugs are in the pipeline for chronic hepatitis B virus (HBV) treatment. There has also been a significant emphasis on screening and surveillance programs, widespread availability of vaccines, and linkage of care. Despite these efforts, significant gaps persist in care, and there is a pressing need for increased collaboration and teamwork across the globe to achieve a reduction of disease burden and elimination of HBV and HCV.

Deep learning time series prediction models in surveillance data of hepatitis incidence in China

Background

Precise incidence prediction of Hepatitis infectious disease is critical for early prevention and better government strategic planning. In this paper, we presented different prediction models using deep learning methods based on the monthly incidence of Hepatitis through a national public health surveillance system in China mainland.

Methods

We assessed and compared the performance of three deep learning methods, namely, Long Short-Term Memory (LSTM) prediction model, Recurrent Neural Network (RNN) prediction model, and Back Propagation Neural Network (BPNN) prediction model. The data collected from 2005 to 2018 were used for the training and prediction model, while the data are split via 5-Fold cross-validation. The performance was evaluated based on three metrics: mean square error (MSE), mean absolute error (MAE), and mean absolute percentage error (MAPE).

Results

Among the year 2005–2018, 20,924,951 cases and 11,892 deaths were supervised in the system. Hepatitis B (HB) is the most disease-causing incidence and death, and the proportion is greater than 70 percent, while the percentage of the incidence and deaths is decreased much in 2018 compared with 2005. Based on the measured errors and the visualization of the three neural networks, there is no one model predicting the incidence cases that can be completely superior to other models. When predicting the number of incidence cases for HB, the performance ranking of the three models from high to low is LSTM, BPNN, RNN, while it is LSTM, RNN, BPNN for Hepatitis C (HC). while the MAE, MSE and MAPE of the LSTM model for HB, HC are 3.84*10⁻⁰⁶, 3.08*10⁻¹¹, 4.981, 8.84*10⁻⁰⁶, 1.98*10⁻¹²,5.8519, respectively.

Conclusions

The deep learning time series predictive models show their significance to forecast the Hepatitis incidence and have the potential to assist the decision-makers in making efficient decisions for the early detection of the disease incidents, which would significantly promote Hepatitis disease control and management.

Therapy of Chronic Viral Hepatitis: The Light at the End of the Tunnel?

Chronic viral hepatitis determines significant morbidity and mortality globally and is caused by three main etiological actors (Hepatitis B Virus, Hepatitis C Virus, and Hepatitis D Virus) with different replicative cycles and biological behaviors. Thus, therapies change according to the different characteristics of the viruses. In chronic hepatitis B, long term suppressive treatments with nucleoside/nucleotide analogues have had a dramatic impact on the evolution of liver disease and liver-related complications. However, a conclusive clearance of the virus is difficult to obtain; new strategies that are able to eradicate the infection are currently objects of research. The therapy for Hepatitis D Virus infection is challenging due to the unique virology of the virus, which uses the synthetic machinery of the infected hepatocyte for its own replication and cannot be targeted by conventional antivirals that are active against virus-coded proteins. Recently introduced antivirals, such as bulevertide and lonafarnib, display definite but only partial efficacy in reducing serum HDV-RNA. However, in combination with pegylated interferon, they provide a synergistic therapeutic effect and appear to represent the current best therapy for HDV-positive patients. With the advent of Direct Acting Antiviral Agents (DAAs), a dramatic breakthrough has occurred in the therapeutic scenario of chronic hepatitis C. Cure of HCV infection is achieved in more than 95% of treated patients, irrespective of their baseline liver fibrosis status. Potentially, the goal of global HCV elimination by 2030 as endorsed by the World Health Organization can be obtained if more global subsidised supplies of DAAs are provided.

HDV infection in immigrant populations

AIMS

Little data have been published so far on the epidemiological aspects of hepatitis D virus (HDV) infection in immigrant populations and even poorer is the information on the virological, phylogenetic, and clinical aspects of this infection in these populations. This review article, aimed primarily at physicians caring for immigrants, summarizes the information available on HDV infection and analyzes data on this topic concerning the immigrant populations.

METHODS AND RESULTS

The prevalence of HDV infection in HBsAg-positive immigrants varies according to the country of origin. For example, in immigrants from sub-Saharan Africa, this prevalence is higher in those born in Equatorial Guinea (24.4%) than those from other African countries (10.3%). The epidemiological impact of HDV infection linked to migratory flows is a function of the different endemicity between countries of origin and countries in which a new existence has been established. This impact is high when immigrants from areas endemic to HDV infection (eg, Equatorial Guinea) settle in areas of low endemicity (eg, Germany or England, with a prevalence of around 4%), while the impact is lesser or nonexistent if the migratory flows are directed toward countries with intermediate endemicity (eg, Italy and Greece, with a prevalence of around 10%).

CONCLUSION

This impact of immigration on HDV epidemiology can be strong when HDV endemicity is high in the country of origin and low in the host country and slight when immigrants move to high or medium endemic countries.

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.

Hepatitis delta virus and hepatocellular carcinoma: an update. Epidemiol Infect. 2018;146:1612-1618. [PMID: 29991359 DOI: 10.1017/s0950268818001942]

Hepatitis delta virus (HDV) is a defective RNA virus that depends on the presence of hepatitis B virus (HBV) for the creation of new virions and propagation of the infection to hepatocytes. Chronic infection with HDV is usually associated with a worsening of HBV infection, leading more frequently to cirrhosis, increased risk of liver decompensation and hepatocellular carcinoma (HCC) occurrence. In spite of a progressive declining prevalence of both acute and chronic HDV infection observed over several years, mainly due to increased global health policies and mass vaccination against HBV, several European countries have more recently observed stable HDV prevalence mainly due to migrants from non-European countries. Persistent HDV replication has been widely demonstrated as associated with cirrhosis development and, as a consequence, development of liver decompensation and occurrence of HCC. Several treatment options have been attempted with poor results in terms of HDV eradication and improvement of long-term prognosis. A global effort is deemed urgent to enhance the models already existing as well as to learn more about HDV infection and correlated tumourigenesis mechanisms.

Investigational drugs in development for Hepatitis D

INTRODUCTION

Treatment of chronic hepatitis D still relies on Interferon. To improve efficacy, new therapeutic strategies are in development which aim to deprive the Hepatitis D Virus (HDV) of functions of the Hepatitis B Virus and of the host required for its life-cycle. Areas covered: The therapeutic options are; 1) The inhibition of the farnesylation of the large HD-protein permissive of virion assembly with Lonafarnib, 2) The blocking of HBsAg entry into cells with Myrcludex B via the inhibition of the Sodium Taurocholate Cotransporting Receptor, to prevent the spreading of HDV to uninfected hepatocytes, 3) The reduction of subviral HBsAg particles by REP 2139, leading to diminished virion morphogenesis . Expert opinion: Lonafarnib and Myrcludex reduced serum HVD-RNA; neither diminished serum HBsAg. NAP REP-2139 diminished both HDV-RNA and HBsAg in serum; a full report is awaited. In combination with Peg-Interferon, these new drugs may provide additional efficacy.

Adefovir Dipivoxyl for the Treatment of Delta-Related Liver Cirrhosis

Objective:

To report a case suggesting the beneficial effect of adefovir dipivoxyl in patients with delta-related decompensated liver cirrhosis ineffectively treated with lamivudine.

Case Summary:

A 55-year-old woman with chronic hepatitis B virus (HBV), antihepatitis Be positive, and hepatitis delta virus (HDV)–related decompensated liver cirrhosis (Child–Pugh score B9) was awaiting liver transplantation. During this time, she was treated with lamivudine 100 mg/day; however, the drug was stopped after 8 months because it did not produce viral clearance or return serum aminotransferase levels to within normal limits. The patient was not a candidate for interferon alfa therapy but was prescribed adefovir dipivoxyl 10 mg/day. Five months later, serum aminotransferase levels had normalized and, after 7 months of treatment with adefovir, the patient became negative for serum HBV-DNA and immunoglobulin M (IgM) antidelta. At the time of writing (20 mo of therapy), the HBV-DNA and IgM antidelta remained negative, whereas hepatitis B surface antigen and circulating HDV-RNA were positive. No adverse effects associated with adefovir were reported, and the Child–Pugh score (A6) had improved.

Discussion:

This is the first reported case of some beneficial biochemical and serologic effects of adefovir dipivoxyl in the treatment of delta cirrhosis. The virologic pattern of the patient after adefovir is indicative of poor liver disease activity and prospectively enhances liver transplantation outcome, indicating that adefovir might also be useful in the phase prior to liver transplantation.

Conclusions:

Although we have no plausible explanation for our patient's favorable response to adefovir treatment, this case contributes to the knowledge regarding treatment of this very difficult condition as well as adefovir efficacy. Given the positive outcome, this report suggests that adefovir might be beneficial in patients with delta-related liver cirrhosis not responsive to previous lamivudine therapy. Based on the high tolerability of this therapy, this case encourages clinical trials.

HBsAg kinetics in chronic hepatitis D during interferon therapy: on-treatment prediction of response

BACKGROUND

Therapy of chronic hepatitis D with Interferon is successful when testing for HDV-RNA turns negative. This end-point is disputed.

AIM

To assess the role of serum hepatitis B surface antigen (HBsAg) in the clearance of HDV-RNA in pegylated interferon (Peg-IFN)-treated chronic hepatitis D (CHD).

METHODS

Sixty-two patients with CHD, treated with Peg-IFN, were considered. The patients belonged to three groups: 14 patients cleared the HBsAg and HDV-RNA (responders, R), 12 cleared the HDV-RNA remaining positive for HBsAg (partial responders, PR) and 36 cleared neither the HBsAg nor the HDV-RNA (nonresponders, NR).

RESULTS

In responders, at baseline the median value (mv) of HBsAg and HDV-RNA was 1187 and 188 663 IU/mL. By month 6 of therapy, HBsAg declined to less than 1000 IU/mL and HDV-RNA was undetectable in 12 patients. In NR, the pre-therapy median value of HBsAg and HDV viremia was 6577 and 676 319 IU/mL. There was no significant reduction of antigen at month 6; after a decline, HDV-RNA rebounded to baseline levels. In PR, the median value of baseline HBsAg was 7031 IU/mL; it declined at month 6 in the majority. HDV-RNA progressively declined from an initial median value of 171 405 IU/mL. HBsAg <1000 IU/mL at month 6 discriminated responders and PR from NR (P < 0.001). By ROC curve, the threshold of 0.105 log reduction of HBsAg associated with 1.610 log reduction of HDV-RNA from baseline to month 6 predicted the clearance of this marker.

CONCLUSIONS

A reduction of serum HBsAg is mandatory for the definitive clearance of the HDV-RNA. Quantitative HBsAg may predict the long-term response to Peg-IFN therapy and provide a guide to prolong or stop treatment.

The adventure of delta

The hepatitis D virus (HDV) is unique in animal virology. It has a circular RNA genome that is the smallest of human viruses, requires the HBsAg capsid of the hepatitis B virus to assembly into infectious virions, parasitizes the transcriptional machinery of the host by hijacking cellular RNA polymerases to replicate its RNA genome and is replicated by a rolling circle mechanism unknown to mammalian cells. Hepatitis D is ubiquitous but prevalence varies throughout the world. It is the most severe form of chronic viral liver disorder; carriers of HBsAg superinfected by the HDV are the major victims and the reservoir of the infection. In the last 20 years vaccination against the hepatitis B virus (HBV) has decreased the circulation of HDV in industrialized countries; nevertheless hepatitis D is returning to Western Europe through immigration from HDV endemic areas. Hepatitis D is being rediscovered in the developing world. It has a significant medical impact on areas of Africa, Asia and South America where the partner HBV is not controlled; Pakistan and Mongolia appear to be worldwide the areas with the highest prevalence of the disease. A major obstacle in treatment is that the virus has no replicative function of its own to be targeted by antivirals. Peg-Interferon remains the mainstay of treatment. New strategies are explored to prevent entry of the virion into hepatocytes by blocking the cellular HBsAg receptor or preventing the prenylation process of the large-delta antigen necessary for the assembly of the HDV particle.

Hepatitis D in Children

Hepatitis D virus (HDV) is an uncommon, defective, single-stranded circular RNA virus that is dependent on the hepatitis B virus' surface antigen envelope proteins for transmission. It is highly pathogenic and associated with high rates of progression to cirrhosis and associated complications. HDV continues to ravage endemic parts of Asia and Europe, and its prevalence in the United States, although low, has not decreased in frequency, despite universal hepatitis B virus vaccination, because of lack of testing and underrecognition. There are few reports on the prevalence and characteristics of HDV infection in the pediatric population. We present 2 patients with HDV infection at our institution; both were from eastern Europe and were treated with pegylated interferon-α. The present standard of care treatment for HDV yields suboptimal results, but insights into the virology of hepatitis D are stimulating the search for novel therapeutic approaches, particularly the development of prenylation inhibitors and viral entry inhibitors.

Therapy of Delta Hepatitis

Delta hepatitis is the less frequently encountered but most severe form of viral hepatitis. Acute delta hepatitis, as a result of coinfection with hepatitis B and hepatitis delta, is rare, but may lead to fulminant hepatitis, and no therapy exists for this form. Chronic delta hepatitis (CDH) mostly develops as a result of superinfection of a hepatitis B surface antigen (HBsAg) carrier with hepatitis delta virus (HDV). In general, HDV is the dominant virus. However, a dynamic shift of the dominant virus may occur with time in rare instances, and hepatitis B virus (HBV) may become the dominant virus, at which time nucleos(t)ide analog therapy may be indicated. Otherwise, the only established management of CDH consists of conventional or pegylated interferon therapy, which has to be administered at doses used for hepatitis B for a duration of at least 1 year. Posttreatment week-24 virologic response is the most widely used surrogate marker of treatment efficacy, but it does not represent a sustained virologic response, and late relapse can occur. As an easy-to-use simple serological test, anti-HDV-immunoglobulin M (IgM) correlates with histological inflammatory activity and clinical long-term outcome; however, it is not as sensitive as HDV RNA in assessing treatment response. No evidence-based rules for treating CDH exist, and treatment duration needs to be individualized based on virologic response at end of treatment or end of follow-up. Effective treatment may decrease liver-related complications, such as decompensation or liver-related mortality. In patients with decompensated cirrhosis, interferons are contraindicated and liver transplantation has to be considered. Alternative treatment options are an urgent need in CDH. New treatment strategies targeting different steps of the HDV life cycle, such as hepatocyte entry inhibitors or prenylation inhibitors, are emerging and provide hope for the future.

Development and evaluation of a baseline-event-anticipation score for hepatitis delta

Hepatitis delta is considered the most severe form of viral hepatitis, but variables associated with disease progression are poorly defined. This study aimed to identify risk factors associated with worse clinical outcome in patients with hepatitis delta and to develop a clinical score to determine their risk of experiencing liver-related morbidity or mortality. We followed 75 HBsAg-anti-HDV-positive patients with hepatitis delta for up to 16 years (median 5 years). The baseline-event-anticipation score (BEA score) was developed based on variables associated with the development of liver-related clinical complications. Age, region of origin, presence of cirrhosis, albumin, INR, hyperbilirubinemia and thrombocytopenia were all associated with the development of an event in the training cohort. The BEA score included age, sex, region of origin, bilirubin, platelets and INR. Points were allocated according to hazard ratios, and three risk groups were defined: BEA-A mild risk, BEA-B moderate risk and BEA-C high risk. Hazard ratios of BEA-B and BEA-C patients for liver-related clinical endpoints were 9.01 and 25.27 vs BEA-A with an area under curve of the receiving operating characteristic curve of 0.88. The accuracy of the BEA score was confirmed in two independent validation cohorts followed in Barcelona (n = 77) and Düsseldorf (n = 62). Delta hepatitis is associated with a very severe long-term outcome. The BEA score is easy to apply and predicts with a very high accuracy the development of liver-related complications in patients with hepatitis delta.

The impact of vaccination and antiviral therapy on hepatitis B and hepatitis D epidemiology

The major cause of liver cancer around the globe is hepatitis B virus (HBV), which also contributes to a large number of deaths due to liver failure alone. Hepatitis delta virus (HDV) is as potentially alarming as HBV since life threatening cases are 10 times more likely with HBV-HDV dual infection compared to HBV monoinfection. So far, there is no established effective treatment against HDV and the only preventive action suggested by the World Health Organization is to introduce HBV vaccination for children immediately after birth (newborns) and thus reduce the available pool for HDV infection. Here the main objective is to understand the complex dynamics of HBV-HDV infection in a human population that can inform public health policy makers on the level of different preventive measures required to eliminate HBV and HDV infections. Model simulations suggest that HBV vertical transmission and HBV vaccination rates for newborns are instrumental in determining HBV and HDV prevalence. A decrease in HBV prevalence is observed as vaccination coverage increases and it is possible to eradicate both HBV and HDV using high vaccination coverage of ≥80% in the long term. We further found that HDV presence results in lower HBV prevalence. An application of our model to China revealed that vaccinating every newborn in China will further prevent 1.69 million new infections by 2028 as compared to the current 90% vaccination coverage. Although, higher vaccination coverage of newborns should eliminate both HBV and HDV over a long time period, any short term strategy to eradicate HDV must include additional preventive measures such as HBV adult vaccination. Implementation of HBV adult vaccination programs at a rate of 10% per year over 15 years will further prevent 39 thousand new HDV infections in China by 2028 as compared to HBV vaccination programs solely for newborns.

Chronic hepatitis D at a standstill: where do we go from here?

Immigration is fuelling a new reservoir of hepatitis D virus (HDV) in Europe, and hepatitis D still represents an important medical problem in the USA. The disease continues to be a major medical scourge in the developing world, in particular in countries such as Pakistan, Mongolia and Mauritania. New therapeutic strategies are being developed to disrupt interactions between HDV and its viral partner HBV, or with the host. Blocking or modifying the hepatitis B surface antigen (HBsAg) might interfere with the uptake or release of the hepatitis D virion; interference with host-mediated post-translational changes of proteins that are crucial to the HDV life cycle, such as prenylation, is another potential therapeutic option. At present, however, the only realistic option is to optimize IFN-α therapy. As eradication of HBsAg is the ultimate end point of therapy, long-term interferon administration might be required, raising an issue of tolerance in patients. Treatment with IFN-λ is a potential alternative approach to IFN-α; treatment of hepatitis C with this cytokine seems to cause fewer adverse effects than IFN-α and, therefore, might be more suitable for long-term treatment of HDV.

Hepatitis delta virus: a peculiar virus

The hepatitis delta virus (HDV) is distributed worldwide and related to the most severe form of viral hepatitis. HDV is a satellite RNA virus dependent on hepatitis B surface antigens to assemble its envelope and thus form new virions and propagate infection. HDV has a small 1.7 Kb genome making it the smallest known human virus. This deceivingly simple virus has unique biological features and many aspects of its life cycle remain elusive. The present review endeavors to gather the available information on HDV epidemiology and clinical features as well as HDV biology.

Hepatitis D virus infection in the Western Brazilian Amazon - far from a vanishing disease

INTRODUCTION

A decline in hepatitis D virus (HDV) occurrence was described in Europe and Asia. We estimated HDV prevalence in the Brazilian Amazon following hepatitis B vaccination.

METHODS

This is a cross-sectional survey of HDV measured by total antibodies to HDV (anti-HD T).

RESULTS

HDV prevalence was 41.9% whiting HBsAg carries and was associated with age (PR = 1.96; 95% CI 1.12-3.42; p = 0.01), hepatitis B virus (HBV) infection (PR = 4.38; 95% CI 3.12-6.13; p < 0.001), and clinical hepatitis (PR =1.44; 95% CI 1.03-2.00; p = 0.03). Risk factors were related to HDV biology, clinical or demographic aspects such as underlying HBV infection, clinical hepatitis and age.

CONCLUSIONS

Our study demonstrated that HDV infection continues to be an important health issue in the Brazilian Amazon and that the implementation of the HBV vaccination in rural Lábrea had little or no impact on the spread of HDV. This shows that HDV has not yet disappeared from HBV hyperendemic areas and reminding that it is far from being a vanishing disease in the Amazon basin.

Development and assessment of a novel real-time PCR assay for quantitation of hepatitis D virus RNA to study viral kinetics in chronic hepatitis D

Hepatitis delta virus (HDV) infection is a usually severe type of viral hepatitis associated with increased mortality and rapid evolution to cirrhosis. Currently, treatment is limited to extended interferon administration and measurement of HDV RNA blood levels is essential to judge the response. The aim of this study was to develop a highly sensitive and reproducible real-time reverse transcriptase-polymerase chain reaction (real-time RT-PCR) for the quantitation of circulating HDV RNA of all clades (1-8), and assess its usefulness in the follow-up of patients. The amplification was combined with molecular beacon technology using the LightCycler 2.0 system. The assay was specific and showed linearity over a wide range from 13 to 13 × 10(10) copies/mL. The 95% detection limit was 43.2 copies/mL. Intra-assay reproducibility, as expressed by the coefficient of variation, ranged from 1.84 to 18.61%, whereas the corresponding estimates for the inter-assay variability ranged from 0.57 to 10.18%. Finally, the dynamic profiles of six patients regarding virological (HDV RNA, HBV DNA), biochemical and serological data were constructed. We were able to observe that most patients who were treated with an interferon-based regime showed a significant reduction in delta viremia. In conclusion, our real-time RT-PCR for HDV RNA quantification combines high sensitivity and reproducibility in a high dynamic range, can provide important information for patient management and can be a useful tool for monitoring the response to antiviral therapies.

Liver transplantation for HBV-related cirrhosis in Europe: an ELTR study on evolution and outcomes

BACKGROUND & AIMS

HBV-related chronic liver disease is one of the most common indications for liver transplantation (LT) in Europe. The ELTR database was used to evaluate outcomes and evolution over 20 years (01/1988 and 12/2010).

METHODS

HBV transplanted patients were analysed according to indication for LT: decompensated cirrhosis (HBVdec) or hepatocellular carcinoma (HBV/HCC). These groups were compared with co-infected patients HBV/HDV (HBDV), HBV/HCV (HBCV), HBV/HDV/HCV (HBDCV); n = 16,664 and with HCV patients (n = 2452) according to LT indication.

RESULTS

5912 patients were transplanted for HBV (78% HBVdec, 22% HBV/HCC), with HBV/HCC patients who increased from 15.8% in 1988-1995 to 29.6% in 2006-2010 (p < 0.001). In HBVdec patients, 1, 3, 5, and 10 year patient and graft survival was 83%, 78%, 75%, 68%, and 80%, 74%, 71%, 64%, respectively, significantly better than HBV/HCC (84%, 73%, 68%, 61%, and 81%, 70%, 65%, 58% respectively; p = 0.001 and p = 0.026). In 2006-2010 patient and graft survival significantly improved compared to 1988-1995, both for HBVdec and HBV/HCC (each p < 0.001). A better patient and graft survival was seen in HBV/HCC patients with HBV-DNA(-) compared to HBV-DNA(+) at the time of LT (p < 0.001). Disease recurrence, as cause of death/graft loss, was significantly reduced in recent years compared to the past: currently <1% for HBVdec and 3% for HBV/HCC.

CONCLUSIONS

Outcomes of LT for HBV have improved in recent years, with disease recurrence being no longer a significant cause of death/graft loss. HBV-DNA at the time of LT seems to influence survival only in HBV/HCC patients.

Current management of delta hepatitis

Interferon is the only therapy for chronic hepatitis D. Nucleos(t)ides are not effective against the helper hepatitis B virus. The current therapeutic recommendation is a weekly dose of pegylated interferon (PEG-IFN)-α, for 12-18 months. Serum HDV-RNA only becomes undetectable after 6 months of therapy in about a quarter of the patients. Hepatitis D virus (HDV) may relapse in patients if they remain HBsAg positive. Although the end-point of therapy is the clearance of the HBsAg, this is seldom achieved. Current management of HDV patients is based on standard practices which should be pragmatic and individualized.

Interferon-α for patients with chronic hepatitis delta: a systematic review of randomized clinical trials

BACKGROUND

Hepatitis delta virus (HDV) infection therapy is unclear. This systematic analysis aimed to clarify the evidence on the efficacy of interferon (IFN)-α-based therapy in HDV.

METHODS

We performed a systematic search on electronic databases including MEDLINE (1970 to January 2011), Web of Science, The Cochrane Library and ClinicalTrials.gov. Randomized clinical trials (RCTs) comparing IFN-α-based therapy with either another drug, placebo or no intervention were included. We excluded paediatric studies. We calculated relative risks (RRs) for comparison of treatment options on the primary outcome measure, which was defined as undetectable levels of HDV RNA and normal alanine aminotransferase at end of treatment (EOT; 1 year).

RESULTS

Nine RCTs were included. Seven trials evaluated the treatment with IFN-α (n=132). The remaining two trials evaluated treatment with pegylated (PEG)-IFN-α (n=45). We found that 1-year treatment with high-dose IFN-α achieved better primary outcome rates than with PEG-IFN-α (RR=4.14, 95% CI 1.00, 17.14). Data for 1-year treatment with low-dose IFN-α compared with PEG-IFN-α were similar (RR=2.83, 95% CI 0.65, 12.40), as were low-dose IFN-α versus high-dose IFN-α (RR=0.68, 95% CI 0.31, 1.50). High-dose IFN-α and PEG-IFN-α reached similar HDV RNA suppression 24 weeks after EOT (RR=1.00, 95% CI 0.51, 1.97). None of the 55 patients assigned to no intervention obtained undetectable levels of HDV RNA and only one patient achieved normalization of alanine aminotransferase level.

CONCLUSIONS

Based on available RCTs, 1-year high-dose IFN-α monotherapy appears to be more effective than PEG-IFN-α for treatment of HDV patients, with efficacy rates of approximately 30%. There is a lack of head-to-head comparisons. Combination therapies and longer treatment duration need to be investigated.

Interferon alpha for chronic hepatitis D

BACKGROUND

Hepatitis D virus is a small defective RNA virus that requires the presence of hepatitis B virus infection to infect a person. Hepatitis D is a difficult-to-treat infection. Several clinical trials have been published on the efficacy of interferon alpha for hepatitis D virus (HDV) infection. However, there are few randomised trials evaluating the effects of interferon alpha, and it is difficult to judge any benefit of this intervention from the individual trials.

OBJECTIVES

To evaluate the beneficial and harmful effects of interferon alpha for patients with chronic hepatitis D.

SEARCH METHODS

We identified relevant for the review randomised clinical trials by electronic searches in the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded until May 2011. We also checked the bibliographic references of identified randomised trials, textbooks, and review articles in order to find randomised trials not identified by the electronic searches.

SELECTION CRITERIA

Randomised clinical trials evaluating interferon alpha versus placebo or no intervention for patients with chronic hepatitis D infection.

DATA COLLECTION AND ANALYSIS

Two authors assessed the trials and extracted data on mortality, virologic, biochemical, and histological response as well as adverse events at end of treatment and six months or more after completing treatment. The analyses were performed using the intention-to-treat principle including all randomised participants irrespective of follow-up. Drop-outs, withdrawals, and non-compliance were considered as treatment failures. Data were analysed with fixed- and random-effects models. Reported results were based on fixed-effect model except in cases where statistical significance varied between the two models.

MAIN RESULTS

Six randomised trials fulfilled the inclusion criteria. Two hundred and one randomised participants (male = 174) were included. The risk of bias in all the included trials was high. Five trials compared interferon alpha with no treatment in the control group. One of these trials had two treatment arms with a higher dose and lower dose of interferon alpha and a no-treatment control group. We analysed both treatment regimens as a single group in a primary analysis and as separate groups in the subgroup analysis of different interferon dosages. The sixth trial compared only a higher dose of interferon alpha with a lower dose.Meta-analysis of five trials comparing interferon alpha with no-treatment control group included 169 participants. There were seven drop-outs in the treatment group and nine in the control group. One patient out of 92 (1.1%) died in the interferon alpha group compared with zero out of 77 (0.0%) in the no-intervention control group (risk ratio (RR)) 3.00; 95% confidence interval (CI) 0.14 to 66.5). Interferon alpha led to failure of end of treatment virological response in 62/92 (67.4%) of the patients compared with 71/77 (92.2%) in the untreated controls (RR 0.76, 95% CI 0.66 to 0.87, P = 0.0001 by fixed-effect model and RR 0.71, 95% CI 0.43 to 1.16, P = 0.17 by random-effects model). Failure of normalisation of alanine aminotransferase (ALT) at the end of treatment was seen in 60/92 (65.2%) patients treated with interferon alpha versus 76/77 (98.7%) in the control group (RR 0.69, 95% CI 0.59 to 0.80, P < 0.00001). Sustained virological response was not achieved in 76/92 (82.6%) of patients on interferon compared with 73/77 (94.8%) of controls (RR 0.89, 95% CI 0.80 to 0.98, P = 0.02). Serum alanine aminotransferase was abnormal in 81/92 (88.0%) treated with interferon alpha patients at six months post-treatment follow-up compared with 76/77 (98.7%) in controls (RR 0.92, 95% CI 0.84 to 0.99, P = 0.04). There was no significant histological improvement in 67/92 (72.8%) patients treated with interferon alpha compared with 65/77 (84.4%) in controls (RR 0.86, 95% CI 0.74 to 1.00, P = 0.06).Two trials comparing a higher dose of interferon alpha with the lower dose showed no significant difference in sustained virological response (76.7% compared with 90.0%) (RR 0.85, 95% CI 0.68 to 1.07, P = 0.16). Adverse events such as flu-like symptoms, asthenia, weight loss, alopecia, thrombocytopenia, and leukopenia were reported in all these trials and the adverse events were related to interferon alpha. These were common and sometimes severe. One patient in the treatment group was reported to have died by suicide towards the end of the study period.

AUTHORS' CONCLUSIONS

Interferon alpha does not seem to cure hepatitis D in most patients. The agent seems effective in suppressing viral and liver disease activity in some patients, but this improvement is not sustained in the majority of patients. We cannot exclude overestimation of benefits and underestimation of harms due to high risk of bias (systematic errors) and high risk play of chance (random errors). Therefore, more randomised trials with large sample sizes and less risk of bias are needed before interferon can be recommended or refuted.

HDV: thirty years later

The hepatitis D virus (HDV) was discovered in Italy in the mid-1970s during a major outbreak of hepatitis D in the Mediterranean basin. The outbreak has been brought under control in Europe and throughout the industrialized world in the last twenty years; in parallel, the clinical pattern of HDV disease has consistently changed. Though the decline of hepatitis D has diminished attention to this problem and at present testing for HDV is not seldom neglected, hepatitis D is not eradicated in Europe and its circulation did not decline further in the last decade. Fresh new cases are cumulating in migrants from HDV endemic areas of the developing world. Hepatitis D remains a major health problem in many developing areas with outbreaks of the disease continuing to be reported from Asia, Africa and South Africa.

Hepatitis D revival

More than 30 years after Mario Rizzetto and colleagues described a new antigen in livers of HBsAg-positive patients called the "delta antigen", a re-emerging interest in hepatitis delta is currently observed. The state-of-the art on basic and clinical research on hepatitis delta was presented during a monothematic conference organized by the European Association for the Study of the Liver (EASL) in September 2010. Hepatitis delta is caused by infection with the hepatitis D virus (HDV) which requires presence of HBsAg for complete replication and transmission. Recent data confirmed the severe long-term course of HDV infection with high rates of hepatic decompensation while controversial data on the risk for the development of hepatocellular carcinoma were reported. Pegylated interferon alpha can lead to sustained HDV RNA elimination in about one quarter of patients while HBV polymerase inhibitors are ineffective against HDV. Novel treatment options include prenylation inhibitors and HBV entry inhibitors which are currently in early clinical development.

Outcome of chronic delta hepatitis in Italy: a long-term cohort study

BACKGROUND & AIMS

To investigate the impact of HDV infection on morbidity and mortality of patients.

PATIENTS AND METHODS

This was a retrospective study on 188 patients that underwent a program of periodic surveillance until 2008. The demographic data, stage of liver disease, treatment efficacy, development of liver complications (ascites, oesophageal bleeding, encephalopathy), and survival were registered. A Cox regression analysis was carried out to determine the impact of viral and patient features on survival.

RESULTS

At baseline, 126 patients (67%) tested positive for serum IgM anti-HDV antibodies, 171 (91%) for anti-HBe, 175 (93%) for serum HDV-RNA, and 61 (33%) for serum HBV-DNA. Eighty-two patients (43%) had chronic hepatitis at histology; the remaining 106 individuals had a clinical/histological diagnosis of cirrhosis. Ninety-six patients received interferon (n = 90) or lamivudine (n = 6) therapy, and 27 of them (30%) attained a sustained response. During follow up, 21 patients with chronic hepatitis progressed to cirrhosis. Of the 127 cirrhotic patients, hepatic decompensation occurred in 42 patients (33%) and hepatocellular carcinoma in 17 (13%). The 5- and 10-year survival free of events were 96.8% and 81.9%, respectively, for patients with chronic hepatitis, and 83.9% and 59.4% for cirrhotics (p<0.01). At multivariate analysis, lack of antiviral therapy (p = 0.01), cirrhosis at presentation (p<0.01), and male sex (p = 0.03) independently predicted a worse outcome.

CONCLUSION

HDV liver disease lasts several decades. Half of all patients who develop cirrhosis later will advance to liver failure. At present, interferon therapy is recommended as soon as possible to slow or alter the natural course of liver disease.

Development of mathematical models for the analysis of hepatitis delta virus viral dynamics

BACKGROUND

Mathematical models have shown to be extremely helpful in understanding the dynamics of different virus diseases, including hepatitis B. Hepatitis D virus (HDV) is a satellite virus of the hepatitis B virus (HBV). In the liver, production of new HDV virions depends on the presence of HBV. There are two ways in which HDV can occur in an individual: co-infection and super-infection. Co-infection occurs when an individual is simultaneously infected by HBV and HDV, while super-infection occurs in persons with an existing chronic HBV infection.

METHODOLOGY/PRINCIPAL FINDINGS

In this work a mathematical model based on differential equations is proposed for the viral dynamics of the hepatitis D virus (HDV) across different scenarios. This model takes into consideration the knowledge of the biology of the virus and its interaction with the host. In this work we will present the results of a simulation study where two scenarios were considered, co-infection and super-infection, together with different antiviral therapies. Although, in general the predicted course of HDV infection is similar to that observed for HBV, we observe a faster increase in the number of HBV infected cells and viral load. In most tested scenarios, the number of HDV infected cells and viral load values remain below corresponding predicted values for HBV.

CONCLUSIONS/SIGNIFICANCE

The simulation study shows that, under the most commonly used and generally accepted therapy approaches for HDV infection, such as lamivudine (LMV) or ribavirine, peggylated alpha-interferon (IFN) or a combination of both, LMV monotherapy and combination therapy of LMV and IFN were predicted to more effectively reduce the HBV and HDV viral loads in the case of super-infection scenarios when compared with the co-infection. In contrast, IFN monotherapy was found to reduce the HDV viral load more efficiently in the case of super-infection while the effect on the HBV viral load was more pronounced during co-infection. The results suggest that there is a need for development of high efficacy therapeutic approaches towards the specific inhibition of HDV replication. These approaches may additionally be directed to the reduction of the half-life of infected cells and life-span of newly produced circulating virions.

Establishment of a novel quantitative hepatitis D virus (HDV) RNA assay using the Cobas TaqMan platform to study HDV RNA kinetics

Determination of hepatitis D virus (HDV) viremia represents the "gold standard" for the diagnosis of HDV infection. Hepatitis B virus (HBV)-HDV coinfection frequently leads to end-stage liver disease and hepatocellular carcinoma. No commercial assay for HDV RNA quantification that includes automated nucleic acid extraction is available, and in-house PCR tests are not well standardized. However, knowledge of HDV RNA levels may give important information for patient management and could be a useful tool for monitoring the response to antiviral therapies. One platform that is widely used for HBV DNA or HCV RNA quantification is the Cobas Ampliprep/TaqMan system. Using the utility channel of this platform, we established a novel protocol for TaqMan-based HDV RNA quantification after automatic extraction of RNA by the Ampliprep system. The assay was specific and showed linearity over a wide range from 3 x 10(2) to 10(7) copies/ml. Reproducibility was demonstrated by determination of the interrun and intrarun variabilities, which were similar to those achieved with the commercially available Cobas TaqMan assays for HCV RNA and HBV DNA. HDV RNA levels were stable in whole blood (n = 4), plasma (n = 3), and serum (n = 3) samples at room temperature for up to 6 days. Importantly, HDV RNA viremia showed only minor fluctuations, with the log(10) coefficient of variation being between 1.3 and 11.2% for hepatitis delta patients studied every 2 weeks for up to 3 months (n = 6), while a rapid viral decline was observed early during treatment with pegylated alfa-2a interferon (n = 6). In conclusion, this novel automated HDV RNA assay is a useful tool for monitoring HDV-infected patients both before and during antiviral therapy.

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

Hepatitis D is caused by infection with the hepatitis D virus (HDV) and is considered to be the most severe form of viral hepatitis in humans. Hepatitis D occurs only in individuals positive for the HBV surface antigen (HBsAg) as HDV is a defective RNA viroid that requires HBsAg for transmission. At least eight different HDV genotypes have been described and each has a characteristic geographic distribution and a distinct clinical course. HDV and HBV coinfection can be associated with complex and dynamic viral dominance patterns. Chronic HDV infection leads to more severe liver disease than HBV monoinfection and is associated with accelerated fibrosis progression, earlier hepatic decompensation and an increased risk for the development of hepatocellular carcinoma. So far, only IFN-alpha treatment has proven antiviral activity against HDV in humans and has been linked to improved long-term outcomes. Studies conducted in the past 2 years on the use of PEG-IFN-alpha show that a sustained virologic response to therapy, measured in terms of undetectable serum HDV RNA levels, can be achieved in about one quarter of patients with hepatitis D. Novel alternative treatment options including prenylation inhibitors are awaiting clinical development for use in hepatitis D.

Hepatitis delta virus large antigen sensitizes to TNF-alpha-induced NF-kappaB signaling

Hepatitis delta virus (HDV) infection causes fulminant hepatitis and liver cirrhosis. To elucidate the molecular mechanism of HDV pathogenesis, we examined the effects of HDV viral proteins, the small hepatitis delta antigen (SHDAg) and the large hepatitis delta antigen (LHDAg), on NF-kappaB signaling pathway. In this study, we demonstrated that TNF-alpha-induced NF-kappaB transcriptional activation was increased by LHDAg but not by SHDAg in both HEK293 and Huh7 cells. Furthermore, LHDAg promoted TRAF2-induced NF-kappaB activation. Using coimmunoprecipitation assays, we demonstrated that both SHDAg and LHDAg interacted with TRAF2 protein. We showed that isoprenylation of LHDAg was not required for the increase of NF-kappaB activity. We further showed that only LHDAg but not SHDAg increased the TNF-alpha-mediated nuclear translocation of p65. This was accomplished by activation of IkappaBalpha degradation by LHDAg. Finally, we demonstrated that LHDAg augmented the COX-2 expression level in Huh7 cells. These data suggest that LHDAg modulates NF-kappaB signaling pathway and may contribute to HDV pathogenesis.

Special populations with hepatitis B virus infection

Treatment of patients with chronic hepatitis B virus (HBV) infection who have advanced disease or comorbidities can be challenging, and recommendations may differ from standard guidelines. Among the special populations that merit specific consideration are patients with compensated or decompensated cirrhosis, organ transplantation, acute hepatitis B, pregnancy, coinfection with hepatitis C and/or D virus, chronic renal failure, and children. Major advances have been made in management of many of these special populations because of recent increasing availability of oral nucleosides, which are generally well tolerated and highly effective despite presence of other morbidities or viral infections. Also important have been changes in the management of hepatitis B during the peri-liver transplantation period that allows for prevention of reinfection in the majority of cases. However, much remains to be done to determine which patients should be treated and which should be monitored on no specific therapy. Outcomes of chronic HBV infection in persons with coinfection and in children have varied from different areas of the world, but it is not clear whether these differences are due to host and racial differences or to viral genotypic differences. Further studies are particularly needed in assessing the safety and efficacy of therapy in pregnant women, in children, and in patients with hepatitis D and C virus coinfection.

Hepatitis D: thirty years after

The key to the discovery of the Hepatitis D Virus (HDV) was the description in Turin, Italy in the mid-1970s of the delta antigen and antibody in carriers of the hepatitis B surface antigen. The new antigen was first thought to be a marker of the Hepatitis B Virus (HBV) and in view of its intricate true nature, it would have possibly died away as another odd antigenic subtype of HBV, like many that were described in the 1970s. Fortunately, instead, a collaboration started in 1978 between the Turin group, and the National Institute of Health and Georgetown University in the US. With American facilities and expertise this collaboration led just a year later, in 1979, to the unfolding of an unexpected and amazing chapter in virology. Experiments in chimpanzees demonstrated that the delta antigen was not a component of the HBV but of a separate defective virus requiring HBV for its infection; it was named the hepatitis D virus to conform to the nomenclature of hepatitis viruses and classified within the genus Deltavirus. The animal experiments were also seminal in proposing to future clinical interpretation, the paradigm of a pathogenic infection (hepatitis D), that could develop only in HBV-infected patients, was mainly transmitted by superinfection of HDV on chronic HBV carriers and had the ability to strongly inhibit the helper HBV. The discovery of the HDV has driven three directions of further research: (1) The understanding of the replicative and infectious mechanisms of the HDV. (2) The assessment of its epidemiological and medical impact. (3) The search for a therapy for chronic hepatitis D (CHD). This review summarizes the progress achieved in each field of research in the thirty years that have passed since the discovery of HDV.

How hepatitis D virus can hinder the control of hepatitis B virus

Background

Hepatitis D (or hepatitis delta) virus is a defective virus that relies on hepatitis B virus (HBV) for transmission; infection with hepatitis D can occur only as coinfection with HBV or superinfection of an existing HBV infection. Because of the bond between the two viruses, control measures for HBV may have also affected the spread of hepatitis D, as evidenced by the decline of hepatitis D in recent years. Since the presence of hepatitis D is associated with suppressed HBV replication and possibly infectivity, it is reasonable to speculate that hepatitis D may facilitate the control of HBV.

Methodology and Principal Findings

We introduced a mathematical model for the transmission of HBV and hepatitis D, where individuals with dual HBV and hepatitis D infection transmit both viruses. We calculated the reproduction numbers of single HBV infections and dual HBV and hepatitis D infections and examined the endemic prevalences of the two viruses. The results show that hepatitis D virus modulates not only the severity of the HBV epidemic, but also the impact of interventions for HBV. Surprisingly we find that the presence of hepatitis D virus may hamper the eradication of HBV. Interventions that aim to reduce the basic reproduction number of HBV below one may not be sufficient to eradicate the virus, as control of HBV depends also on the reproduction numbers of dual infections.

Conclusions and Significance

For populations where hepatitis D is endemic, plans for control programs ignoring the presence of hepatitis D may underestimate the HBV epidemic and produce overoptimistic results. The current HBV surveillance should be augmented with monitoring of hepatitis D, in order to improve accuracy of the monitoring and the efficacy of control measures.

Complete cure of HBV-HDV co-infection after 24weeks of combination therapy with pegylated interferon and ribavirin in a patient co-infected with HBV/HCV/HDV/HIV

Multiple hepatitis co-infections are frequent in HIV-infected patients, often resulting in severe liver diseases that are difficult to treat. We report here the complete resolution of a chronic hepatitis B and D co-infection in a patient who was also infected with HCV and HIV. This cure was observed after 24weeks of combination therapy associating pegylated-IFN and ribavirin, which was initially given to treat HCV. An unexpected and extensive HDV replication was observed in this patient after HBs Ag had cleared from the serum, which was followed by a stable halt in HDV replication. Implications of this unusual observation will be discussed.

Interferons and their use in persistent viral infections

In 2007, the world celebrated the 50th anniversary of the discovery of interferon (IFN) by Isaacs and Lindenmann. Subsequently, the IFN-alpha gene was cloned, fully sequenced and IFN-alpha was produced in recombinant form. Recombinant IFN-alpha is now used as the basis for treatment of chronic hepatitis C virus infection and can also be used to treat certain forms of chronic hepatitis B virus infections. IFNs have also been used in other viral infections, although with less success. The antiviral mechanisms of IFNs are reviewed in this chapter as well as the utility of IFNs in the treatment of persistent viral infections.