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.

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.

Evolution of HBV S-gene in the backdrop of HDV co-infection

HBV-HDV co-infected people have a higher chance of developing cirrhosis, fulminant hepatitis, and hepatocellular carcinoma (HCC) compared to those infected only with HBV. The present study was conducted to investigate HBV genotypes and phylogeny among HBV mono-infected and HBV-HDV co-infected patients, as well as analyze mutations in the surface gene of HBV in mono-infected and co-infected patients. A total of 100 blood samples (50 co-infected with HBV and HDV, and 50 mono-infected with HBV only) were collected for this study. HBV DNA was extracted from patient sera and partial surface antigen gene was amplified from HBV genome using polymerase chain reaction. HBV S gene was sequenced from 49 mono-infected and 36 co-infected patients and analyzed to identify HBV genotypes and phylogenetic patterns. Subsequently, HBV S amino acid sequences were analyzed for mutational differences between sequences from mono- and co-infected patients. HBV genotype D was predominantly found in both mono-infected as well as co-infected patients. Phylogenetic analysis showed the divergence of HBV sequences, between mono- and co-infected patients, into two distinct clusters. HBV S gene mutation analysis revealed certain mutations in HBV-HDV co-infected subjects to be distinct from those found in mono-infected patients. This might indicate the evolution of HBV S gene under selection pressures generated from HDV coinfection.

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.

Coinfection of hepatitis B and hepatitis delta virus in Belgium: a multicenter BASL study. Prospective epidemiology and comparison with HBV mono-infection

Epidemiological data on hepatitis delta virus (HDV) infection in Belgium are lacking. A multicenter questionnaire-based registry on HDV infection was collated between March 1, 2008 and February 28, 2009. It consisted of patients coinfected with hepatitis B virus (HBV) and HDV. The data samples were compared to those of a concurrent registry on HBV infection. Prospective data of patients with HBV-HDV coinfection were collected. Active HBV replication is defined as HBeAg positivity or HBV DNA > 2,000 IU/ml. Forty-four patients from 15 centers were registered. A comparison of 29 patients infected with HDV (registered in the concurrent HBV registry) was made against 785 HBV mono-infected patients. The seroprevalence of patients coinfected with HBV and HDV in Belgium is reported to be 3.7% (29/785), consisting solely of the HBV-HDV coinfected patients in the HBV registry. This rises to 5.5% (44/800) if all patients infected with HDV from the two registries combined are included. The patients coinfected with HBV and HDV had higher (P < 0.05) ALT values and more advanced liver disease (Metavir score ≥F2), but had less active HBV replication and lower HBV DNA titers when compared with the patients infected only with HBV. Additionally, the majority of HBV-HDV coinfected patient was male, and 13.6% (6/44) of the patients that were coinfected HBV and HDV were also infected with HCV. In conclusion, this study provided much needed epidemiological data on the current state of HDV infection in Belgium.

Impact of hepatitis B and delta virus co-infection on liver disease in Mauritania: a cross sectional study

OBJECTIVES

Mauritania is a highly endemic region for hepatitis B (HBV) and delta (HDV) viruses. No data are available on HDV's impact on the severity of liver disease in consecutive HBV-infected patients in Africa. This study evaluated the degree of liver fibrosis in a cohort of chronic HBV carriers.

METHODS

Three-hundred consecutive HBV-infected Mauritanian patients were checked for HDV infection via the detection of anti-HDV antibodies (Ab) and viral RNA. HBV- vs. HBV/HDV-infected patients were compared by physical examination, biological analyses, and the APRI (aspartate aminotransferase to platelet ratio index) and FibroMeter tests for determination of liver fibrosis.

RESULTS

More than 30% of the patients had anti-HDVAb. Among these, 62.2% were HDV-RNA positive. Co-infected patients were older (>8-years) than HBV-mono-infected patients. They had more liver tests abnormalities and clinical or ultrasound signs of liver fibrosis. APRI and FibroMeter scores were also significantly increased in these patients. In multivariate analysis, beyond HDVAb, male gender and HBV-VL >3.7 log IU/mL were the only markers linked to significant liver fibrosis.

CONCLUSIONS

In Mauritania, HDV co-infection worsens liver disease, both clinically and biologically, as confirmed by the APRI and FibroMeter tests. These tests may be useful for the management of delta hepatitis, which is a major health problem in Mauritania.

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.

Hepatitis delta: on soft paws across Germany

INTRODUCTION

Globally, more than 350 million people are considered to be chronic carriers of the hepatitis B virus (HBV) infection; thereof, 15-20 million of these individuals are thought to be coinfected with hepatitis delta virus (HDV). The clinical course depends on the mode of transmission; whereas coinfection commonly resolves, superinfection aggravates the disease and progresses to chronicity in over 90 % of the cases, which, again, results in cirrhosis.

OBJECTIVE

Although many tests are performed in HBV carriers, data on the prevalence of anti-HDV-IgG in Germany are only rarely available and outdated. Therefore, we retrospectively evaluated the seroprevalence of anti-HDV-IgG from the results of our routine service.

MATERIALS AND METHODS

Between January 2000 and October 2011, serum samples from 2,844 patients (carrying hepatitis B surface antigen) admitted to University Hospital Frankfurt am Main, Frankfurt, Germany, were tested for anti-HDV-IgG by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The overall seroprevalence of anti-HDV-IgG in the collective of Frankfurt (n = 2,844) is 7.4 % [95 % confidence interval (CI): 6.4-8.4]. The amount of seropositive men (8.3 %, 95 % CI: 6.9-10) significantly exceeds the female proportion (5.7 %, 95 % CI: 4.3-7.5). The rate of seropositivity to anti-HDV-IgG in this collective of Frankfurt reached a maximum in the year 2003 (10.1 %, 95 % CI: 8.9-11.1). The lowest rate was observable in 2004, where 5.4 % were positive to anti-HDV-IgG.

CONCLUSION

Of the HBV carriers in Germany, 5-8 % reveal serologic evidence of coinfection with HDV. The vaccination against HBV is the key to prevent HDV infection; therefore, vaccination must strongly be propagated further on.

Current hepatitis delta virus type 1 (HDV1) infections in central and eastern Turkey indicate a wide genetic diversity that is probably linked to different HDV1 origins

Hepatitis delta virus (HDV) is a subviral pathogen of humans, a satellite of hepatitis B virus (HBV) that induces severe acute and chronic liver diseases. The genus Deltavirus consists of eight clades or genotypes, with HDV1 being ubiquitous and frequently characterized. In Turkey, HDV1 infection is highly endemic among HBsAg carriers, especially in the southeastern region. In this study, we analyzed 34 samples from patients who were chronically infected with HBV/HDV, originating from 22 cities of rural regions in the central and eastern parts of Turkey, in order to determine the levels of viral replication and genetic diversity. HDV RNA levels ranged between 3.02 and 8.75 Log copies/mL, and HBV DNA was detected in 25 samples (73.5%), with values ranging from 2.53 to 5.30 Log copies/mL. Analysis of nucleotides 900-1280 of HDV genomes (n = 34) and full-length (n = 17) sequences indicated that all of the strains belonged to genotype HDV1. However, a high genetic diversity was observed among the isolates, with a mean full-length dissimilarity score of 13.05%. HDV sequences clustered with sequences from Western Europe (n = 11), Eastern Europe and Asia (n = 19) or Africa (n = 4). HDV1 isolates related to strains of African origin had a serine residue instead of an alanine at position 202 of the large delta protein. HBV preS1 sequences obtained for 34 isolates indicated an HBV/D genotype in all cases. Taken together, our results indicate that in Turkey, where HBV-HDV dual infection is highly endemic, both viruses have high levels of replication, and HDV strains exhibit wide genetic diversity, which might reflect ancient evolution and/or successive outbreaks.

Virological and clinical characteristics of hepatitis delta virus in South Asia

BACKGROUND & AIMS

There is a paucity of data on the impact of hepatitis D virus (HDV) in patients with hepatitis B virus (HBV) infection from South Asia. We studied the impact of HDV co-infection on virological and clinical characteristics.

METHODS

We collected data of 480 patients with HBsAg positive and a detectable HBV DNA PCR, who presented to the Aga Khan University, Karachi and Isra University in Hyderabad, Pakistan in the last 5 years. HDV co-infection was diagnosed on the basis of anti-HDV. ALT, HBeAg, HBeAb and HBV DNA PCR quantitative levels were checked in all patients. We divided all patients into two groups based on anti-HDV, and compared their biochemical, serological & virological labs and clinical spectrum. Clinical spectrum of disease included asymptomatic carrier (AC), chronic active hepatitis (CAH), immuno-tolerant phase (IP), and compensated cirrhosis (CC).

RESULTS

HDV co-infection was found in 169 (35.2%). There were 164 (34.6%) HBeAg positive and 316 (65.4%) HBeAg negative patients. Mean ALT level was 66 ± 73 IU. 233 (48.5%) had raised ALT. HBV DNA level was ≥ 10e5 in 103(21.5%) patients. Overall, among HBV/HDV co-infection, 146/169 (86.4%) had suppressed HBV DNA PCR as compared to 231/311 (74.3%) patients with HBV mono-infection; p-value = 0.002. Among HBeAg negative patients 71/128(55.5%) had raised ALT levels among HBV/HDV co-infection as compared to 71/188 (37.8%) with HBV mono-infection (p-value = 0.002); levels of HBV DNA were equal in two groups; there were 27/128 (21%) patients with CC among HBV/HDV co-infection as compared to 23 (12%) in HBV mono-infection (p-value = 0.009); there were less AC (p-value = 0.009) and more CAH (p-value = 0.009) among HBV/HDV co-infection patients. Among HBeAg positive patients, serum ALT, HBV DNA levels and the spectrum of HBV were similar in the two groups.

CONCLUSIONS

HBV/HDV co-infection results in the suppression of HBV DNA. A fair proportion of HBV/HDV co-infected patients with HBeAg negative have active hepatitis B infection and cirrhosis as compared to those with mono-infection.

Replicative and transcriptional activities of hepatitis B virus in patients coinfected with hepatitis B and hepatitis delta viruses

Hepatitis B virus (HBV) and hepatitis delta virus (HDV) interplay was investigated by examining liver and serum samples from 21 coinfected and 22 HBV-monoinfected patients with chronic liver disease. Different real-time PCR assays were applied to evaluate intrahepatic amounts of HBV DNA, covalently closed circular DNA (cccDNA), pregenomic RNA (pgRNA), pre-S/S RNAs, and HDV RNA. Besides HBV DNA and HDV RNA levels, HBsAg concentrations in the sera were also determined. HDV-coinfected cases showed significantly lower median levels of serum HBV DNA (-5 log), intrahepatic relaxed-circular DNA (-2 log), and cccDNA (-2 log) than those of HBV-monoinfected cases. Interestingly, pgRNA and pre-S/S RNA amounts were significantly lower (both -1 log) in HDV-positive patients, whereas serum HBsAg concentrations were comparable between the two patient groups. Pre-S/S RNA and HBsAg amounts per cccDNA molecule were higher in HDV-positive patients (3-fold and 1 log, respectively), showing that HBV replication was reduced, whereas synthesis of envelope proteins was not specifically decreased. The ratios of cccDNA to intracellular total HBV DNA showed a larger proportion of cccDNA molecules in HDV-positive cases. For these patients, both intrahepatic and serum HDV RNA amounts were associated with cccDNA but not with HBsAg or HBV DNA levels. Finally, HBV genomes with large deletions in the basal core promoter/precore region were detected in 5/21 HDV-positive patients but in no HDV-negative patients and were associated with lower viremia levels. These findings provide significant information about the interference exerted by HDV on HBV replication and transcription activities in the human liver.

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.

Quantitative longitudinal evaluations of hepatitis delta virus RNA and hepatitis B virus DNA shows a dynamic, complex replicative profile in chronic hepatitis B and D

BACKGROUND & AIMS

This study presents a real-time reverse-transcription PCR (rt-RT-PCR) assay for hepatitis delta virus (HDV) RNA quantification, designed to clarify the interplay between HDV and hepatitis B virus (HBV) in chronic infection.

METHODS

Serum HDV-RNA and HBV-DNA were analysed by rt-RT-PCR in a cross-sectional study of 37 untreated chronic HDV patients, 25 of whom were also longitudinally studied.

RESULTS

In the cross-sectional study, both viruses were active in 15 (40.5%) patients and inactive in 4 (10.8%); HDV alone was active in 12 (32.4%) and HBV in 6 (16.2%). The longitudinal study showed seven replication profiles, with considerable fluctuating activity of one or both viruses, including alternating predominance. In 20% of cases, longitudinal HBV/HDV viral loads differed from cross-sectional results, indicating a risk of misinterpreting HBV/HDV interactions when assessing a single determination. Fluctuating HBV replication only increased in the presence of fluctuating HDV activity. HBsAg levels, stable in HBV single infection, fluctuated in HDV chronic infection. The results of both the cross-sectional and longitudinal study call into question the major suppressor effect of HDV over HBV, revealing an important role of HBV.

CONCLUSIONS

Longitudinal evaluation of viremia shows a complex interaction between HBV and HDV and is essential to understand the pathophysiology of chronic HDV infection.

Quantitative HBsAg and HDV-RNA levels in chronic delta hepatitis

Abstract Background: Hepatitis delta virus (HDV) causes severe liver disease.

AIMS

To investigate the quantitative HDV-RNA, HBsAg and hepatitis B virus (HBV)DNA levels in correlation to histological, biochemical and demographical parameters in patients with chronic HDV infection as similar data in a large series of HDV patients are missing.

METHODS

Eighty HDV patients were recruited in Germany, Turkey and Greece; quantitative determination of HDV-RNA, HBsAg and HBV-DNA was performed by real-time polymerase chain reaction, the Architect HBsAg assay and Cobas TaqMan HBV test respectively.

RESULTS

All patients were infected with HDV-genotype 1. Thirty-five patients (48%) had significant fibrosis (Ishak 3-4) and 15 (20.5%) had cirrhosis. HDV viraemia ranged from 1.1 x 10(3) to 8.4 x 10(7) copies/ml with 60% of patients showing HDV-RNA levels above 10(5) copies/ml accompanied by low HBV viraemia (<10(5) copies/ml). However, HDV-RNA and HBV-DNA levels showed no direct inverse correlation. HDV-RNA correlated positively with HBsAg and negatively with age. HBsAg correlated negatively with age and positively with histological grading. Only gamma-glutamyltranspeptidase was independently associated with cirrhosis (P=0.032), while no biochemical parameter was associated with grading.

CONCLUSIONS

(i) HBsAg levels correlated with HDV viraemia in chronic HDV. (ii) Biochemical parameters did not accurately indicate the stage and grade of liver disease in chronic HDV and thus liver biopsy seems to remain the major tool for the evaluation of delta hepatitis patients.

Virological and clinical characteristics of delta hepatitis in Central Europe

Hepatitis D virus (HDV) or delta hepatitis has mainly been studied in Asian and Mediterranean cohorts, but data on virological and clinical characteristics of HDV-infected Central and Northern European patients are limited. We investigated virological patterns, as well as biochemical and clinical features of liver disease in 258 HDV infected patients recruited over a period of 15 years at Hannover Medical School. Virological parameters were compared to 2083 anti-HDV negative hepatitis B surface antigen (HBsAg) positive individuals. In this cohort, (i) HDV infection was associated with both suppressed hepatitis B virus (HBV) and hepatitis C virus (HCV) replication, (ii) the suppression of HBV-DNA and HCV-RNA was not related to HDV-RNA replication, (iii) mean HBsAg levels did not significantly differ between HBV-monoinfected patients and individuals with delta hepatitis, (iv) HCV coinfection was rather frequent as about one third of our delta hepatitis patients tested anti-HCV positive, however, without being associated with more advanced liver disease, (v) delta hepatitis patients presented in a high frequency with an advanced stage of liver disease, and (vi) the course of delta hepatitis did not differ between Turkish-born, Eastern European (EE)-born and German-born patients. In summary, in this cohort of patients which is the largest so far Central European single centre group of delta hepatitis patients, we confirm the presence of frequently severe disease and describe novel virological profiles which require consideration in the management of this difficult to treat group of patients.

Surface gene mutations of hepatitis B virus among high-risk patients with occult hepatitis B virus infection

Surface gene mutants of hepatitis B virus (HBV) have been reported in a variety of patient groups. Because of limited data regarding these mutations in patients with occult HBV infections; we aimed to determine these mutations among high-risk patients with occult HBV infection. The presence of HBV-DNA was determined in patients with isolated anti-HBc by real-time polymerase chain reaction (PCR). Then, surface gene region was amplified by nested PCR and mutations were analyzed after sequencing. The mutations that resulted in nonfunctional hepatitis B surface antigen (HBsAg) were insertion of single nucleotide in 2 cases, which causes frameshift and single-nucleotide replacement, and premature stop codons at Leu15 and Gly10 in the other 2 cases. Amino acid substitution at amino acid position 207(S207N) was found in the other isolates. Our study suggested that "a" region mutations did not play a major role in HBsAg detection, and other genetic and nongenetic factors may be responsible for failure to detect HBsAg by routine laboratory tests.

The increasing prevalence of hepatitis delta virus (HDV) infection in South London

On the basis of historical studies, hepatitis delta virus (HDV) infection is considered uncommon in the United Kingdom (UK) and mainly confined to intravenous drug users. In order to assess the current prevalence of HDV co-infection in patients with chronic hepatitis B (HBV), a retrospective analysis was performed of 962 consecutive HBV-infected adult patients referred to King's College Hospital between January 1st 2000 and March 31st 2006. The 82 subjects positive for HDV antibody (8.5%) had a similar age to those without HDV (median 36 years, interquartile range 30-47, vs. 35 years, 29-43). Excluding non-UK residents, the prevalence of HDV Antibody was 7.1%. Most HDV-infected subjects were born in regions where HDV is endemic, for example, Southern or Eastern Europe (28.1%), Africa (26.8%) or Middle-East (7.3%). Forty one (50%) were considered to have acquired HDV infection via intra-familial transmission but intravenous drug use was still a common route of transmission (24.4%). Comparing HBV/HDV co-infected to HBV mono-infected patients, a higher proportion were hepatitis C antibody positive (25.6% versus 3.8%; odds ratio 8.89, 95% confidence interval 4.4-17.9; P < 0.00001) and more had cirrhosis (26.8% vs. 12.9%; odds ratio 2.64, 95% confidence interval 1.55-4.49; P < 0.0001) but, despite this, the risk of hepatocellular carcinoma was similar (odds ratio 1.34, 95% confidence interval 0.62-2.91). Although HDV infection is reportedly declining in some endemic regions, our data demonstrate a high prevalence in South London. HDV co-infection is associated with increased morbidity and patients with HBV should be tested for HDV infection.

The Epidemiology, Natural History and Prevention of Hepatitis B: Implications of HIV Coinfection

Approximately 350 million people have chronic hepatitis B infection, a leading cause of cirrhosis and hepatocellular carcinoma (HCC). Patients who are infected through parenteral or sexual transmission are also at risk for acquisition of HIV. Concomitant HIV infection can lead to an increased risk of morbidity and mortality from hepatitis B virus (HBV)-related cirrhosis, end-stage liver disease and HCC. This review will focus on the epidemiology, natural history and prevention of HBV infection and the modulating effect of HIV on the clinical expression of HBV disease.

Efficacy of peginterferon alpha-2b in chronic hepatitis delta: relevance of quantitative RT-PCR for follow-up

Hepatitis delta virus (HDV) can cause severe acute and chronic liver disease in patients infected by hepatitis B virus. Interferon alpha at high doses, although poorly efficient, is the only treatment reported to provide some benefit in chronic hepatitis delta. Pegylated interferon alpha (PEG-IFN) has not yet been evaluated. Treatment is usually monitored by the qualitative detection of HDV-RNA in serum. In this study, safety and efficacy of PEG-IFN were assessed in chronic hepatitis delta, and serum HDV-RNA kinetics were determined using quantitative RT-PCR. Fourteen patients with chronic hepatitis delta received subcutaneous PEG-IFN alpha-2b during 12 months (1.5 microg/kg per week). Serum HDV-RNA was quantified at initiation and during the course of therapy, and during the posttreatment follow-up period, which ranged from 6 to 42 months (median 16 months). PEG-IFN alpha-2b was well tolerated, inducing no serious adverse effect. Sustained biochemical response was obtained in 8 patients (57%). At the end of treatment, 8 patients (57%) had achieved virological response (undetectable HDV-RNA). Sustained virological response throughout the posttreatment follow-up period was observed in 6 patients (43%). HDV-RNA kinetics were predictive of the response: after 3 months of PEG-IFN, HDV-RNA levels were significantly lower in the responders than in the nonresponders group (P=.018). After 6 months of therapy, a negative HDV-RNA was predictive of sustained response (P=.021). In conclusion, this preliminary study indicates that PEG-IFN alpha-2b is safe and efficient for treatment of chronic hepatitis delta. The follow-up of HDV-RNA levels during therapy, which allows the differentiation of various profiles of virological responses, improves treatment monitoring.

Natural Course and Treatment of Hepatitis D Virus Infection

Hepatitis D virus (HDV) is a subviral satellite with hepatitis B virus (HBV) as its natural helper virus. After entry into hepatocytes, it utilizes host cellular enzymes to replicate by a double-rolling-circle mechanism. HDV is most often transmitted by contact with contaminated blood and body fluid, similar to HBV infection. Approximately 5% of the global HBV carriers are coinfected with HDV, leading to a total of 10-15 million HDV carriers worldwide. HDV infection can occur concurrently with HBV infection (coinfection) or in a patient with established HBV infection (superinfection). The pathogenesis of HDV remains controversial. A decline in the prevalence of both acute and chronic hepatitis D (CHD) has been observed worldwide. At present, therapy for chronic HDV infection is by the use of interferon-alpha. Compared to chronic hepatitis B or C, CHD treatment requires a higher dosage and a longer duration of treatment, and post-treatment relapses are common. In order to prevent the progression of CHD and its related morbidity and mortality, more effective treatments are needed.

Hepatitis B virus infection: co-infection with hepatitis C virus, hepatitis D virus, and human immunodeficiency virus

Hepatitis B virus (HBV) shares routes of transmission, namely exchange of infected body fluids, sharing of contaminated needles, and blood transfusion, with other hepatotropic viruses, such as hepatitis C virus (HCV) and hepatitis D virus (HDV) and with systemic retroviral infections, such as the human immunodeficiency virus (HIV). Thus, many HBV infected patients are co-infected with other viral pathogens. Co-infection appears to increase the risk of progression of liver disease and may have important ramifications on choice of antiviral medication and treatment regimen. This article reviews the current knowledge of co-infection of HBV with HCV, HDV, and HIV.

Chronic hepatitis delta virus infection with genotype IIb variant is correlated with progressive liver disease

We determined the sequence of the hepatitis delta virus (HDV) genome in 40 Japanese patients, most of whom were from the Miyako Islands, Okinawa, Japan. Consensus sequences from 33 HDV full genomes out of a total of 40 patients were determined by directly sequencing four partially overlapping PCR products. Phylogenetic tree analysis classified these 33 complete HDV genomes as HDV genotype I (two patients), genotype IIa (one patient) and genotype IIb (30 patients). Among the 30 genotype IIb patients, there were two clusters of genetic variants. One group consisted of six isolates showing significant homology with genotype IIb, previously reported from Taiwan. The other group consisted of 24 isolates, whose sequences formed a new genetic subgroup (genotype IIb-Miyako; IIb-M). When the genetic structures were compared in detail between IIb and IIb-M, characteristic variations were found in the C-terminal sequence of the large delta antigen-conferring packaging signal as well as the RNA editing site. Determination of subclasses of genotype IIb in a total of 37 patients, including seven HDV patients whose partial HDV sequence was determined, revealed eight patients with IIb and 29 patients with IIb-M. Although there was no significant difference in the clinical background or virological state of hepatitis B virus between these two groups, patients with genotype IIb-M showed greater progression of chronic hepatitis and cirrhosis than those with genotype IIb (P=0.0009). These data indicate the existence of a genetic subgroup of HDV genotype IIb, which is associated with different clinical characteristics and which could be related to genetic variations in functionally important parts of the HDV genome.

Transition of care between paediatric and adult gastroenterology. Chronic viral hepatitis

Chronic viral hepatitis is a common disease. More than 500 million people have chronic viral hepatitis worldwide. These diseases are due to chronic infection with hepatitis B virus, hepatitis D virus or hepatitis C virus. Chronic viral hepatitis is responsible for severe complications: cirrhosis and hepatocellular carcinoma, which are responsible for major morbidity and mortality worldwide. The prognosis of chronic viral hepatitis depends on the rate of progression of fibrosis, which varies widely from one patient to another. Some factors, such as gender, age, alcohol consumption and immune status, influence the progression of fibrosis. In recent years, treatment of chronic viral hepatitis has markedly improved-especially in chronic hepatitis C, with more than 50% of patients having a sustained response with the combination of pegylated interferon and ribavirin. Also, in chronic hepatitis B, new drugs are available, or being evaluated, and combination therapy could dramatically change future therapeutic strategies.