Re-emerging interest in hepatitis delta: new insights into the dynamic interplay between HBV and HDV

Does hepatitis delta virus have a preference for hepatitis B virus genotype? A systematic review of the literature

Hepatitis delta virus (HDV) is a deficient virus that requires the surface proteins of Hepatitis B virus (HBV) to complete its replication. HDV is thus only found in those already infected with HBV (~5% worldwide). There are eight different HDV genotypes (1-8) and 10 HBV genotypes (A-J), each having fairly distinct geographic distributions. While their pairings may be coincidental based on epidemiological occurrence, some evidence exists regarding possible virologic basis for genotype dominance and patterns. Here we sought to determine which HBV genotype is most often linked with active HDV infection and speculate on whether this may represent a viral 'preference'. Electronic databases with OVID Medline were comprehensively searched for studies published between 1977 and 2022 indexing the word 'genotype' and all permutations of 'HDV' (hepatitis D virus, hepatitis delta, etc.). Primary studies of patient samples reporting genotype data for either or both of HDV and HBV were tabulated. The initial search revealed 419 articles and was narrowed to 133 studies reporting genotype data for either or both HBV and HDV. We limited our search to cases with detectable HDV RNA. These represented over 5800 samples from over 70 countries. Of these, 1947 samples had paired genotype data for both viruses. The most common pairing was HDV-1 with HBV-D, but it remains unclear whether this represents a viral 'preference' or mere co-endemicity of the two viruses. Determining if there is a virologic link between HBV and HDV genotypes may have important implications for emerging HDV and HBV research.

In vitro cell culture models to study hepatitis B and D virus infection

Chronic infection with the hepatitis B virus (HBV) and hepatitis D virus (HDV) can cause a major global health burden. Current medication regimens can repress viral replication and help to control disease progression, but a complete cure is hardly achieved due to the difficulties to eradicate viral templates (cccDNA and integrates). To develop novel curative antiviral therapies for HBV/HDV infection, it is vital to precisely understand the details of the molecular biology of both viruses and the virus-host interactions. One important prerequisite for gaining this aim is the availability of suitable in vitro models that support HBV/HDV infection, replicate both viruses via their authentic template and allow to adequately study host cell responses. The discovery of sodium taurocholate cotransporting polypeptide (NTCP) receptor as the most crucial host factor promoted HBV/HDV research to a new era. Recently, the structure of human NTCP was solved, gaining a deeper understanding of HBV recognition as the bona fide receptor. After decades of continuous efforts, new progress has been achieved in the development of cell culture models supporting HBV/HDV study. This review summarizes the cell culture models currently available, discusses the advantages and disadvantages of each model, and highlights their future applications in HBV and HDV research.

Clinical Application of Droplet Digital PCR for Hepatitis Delta Virus Quantification

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

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

BACKGROUND AND AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Hepatitis D virus seroprevalence in Egyptian HBsAg-positive children: a single-center study

In this study, we investigated the seroprevalence of anti-hepatitis D virus (HDV) antibodies in hepatitis B surface antigen (HBsAg)-positive children after 25 years of obligatory vaccination of infants against hepatitis B virus. This cross-sectional study included 120 treatment-naïve HBsAg-positive children, with a male-to-female ratio of 1.8:1 and a mean age of 7.8 ± 3.8 years (range, 1-17 years). Mothers were positive for HBsAg in 96.6% of the cases. HBeAg-positive chronic infection was observed in 60% of the cases, HBeAg-positive chronic hepatitis in 12.5%, and HBeAg-negative chronic infection in 26.7%. Anti-HDV antibodies were not detected in any of the cases. Thus, there is a lack of anti-HDV antibodies in HBsAg-positive children, despite the current burden in adults.

Hepatitis Delta Virus Acts as an Immunogenic Adjuvant in Hepatitis B Virus-Infected Hepatocytes

Hepatitis delta virus (HDV) requires hepatitis B virus (HBV) to complete its infection cycle and causes severe hepatitis, with limited therapeutic options. To determine the prospect of T cell therapy in HBV/HDV co-infection, we study the impact of HDV on viral antigen processing and presentation. Using in vitro models of HBV/HDV co-infection, we demonstrate that HDV boosts HBV epitope presentation, both in HBV/HDV co-infected and neighboring mono-HBV-infected cells through the upregulation of the antigen processing pathway mediated by IFN-β/λ. Liver biopsies of HBV/HDV patients confirm this upregulation. We then validate in vitro and in a HBV/HDV preclinical mouse model that HDV infection increases the anti-HBV efficacy of T cells with engineered T cell receptors. Thus, by unveiling the effect of HDV on HBV antigen presentation, we provide a framework to better understand HBV/HDV immune pathology, and advocate the utilization of engineered HBV-specific T cells as a potential treatment for HBV/HDV co-infection.

HDV infection affects viral antigen processing and presentation

HDV boosts HBV epitope presentation on HBV/HDV and mono-HBV-infected hepatocytes

Anti-HBV efficacy of T cells engineered with T cell receptors is enhanced by HDV

The effect of Hepatitis D co-infection on the immunologic and molecular profile of Hepatitis B in asymptomatic Chronic Hepatitis B patients in southwest Nigeria

Introduction: Hepatitis D infection causes severe form of viral hepatitis in humans and only affects those with hepatitis B either as a co-infection or superinfection. The aim of this study was to determine the prevalence of Hepatitis D and its effect on the immunologic and molecular profile of Hepatitis B among asymptomatic Chronic Hepatitis B patients in Abeokuta.Methodology: A cross-sectional study of 99 chronic HBV patient who met the inclusion criteria. All the patients were tested for HBsAg, anti HCV, HDV antigen, anti HDV, HBsAg quantification, and HBV DNA quantification. Associations were tested for and P value less than 0.05 was considered significant.Results: The participants included 53 (58%) male and 38 (42%) females with ages ranging from 18 to 69 (means 39 ± 11) years. Ten (11%) participants were positive for HDV-Ag while 1 (1.1%) was positive for anti-HDV. Five (5.5%) were positive for HIV 1 &2 while 1 (1.1%) was positive for anti HCV. HBV DNA quantification ranged from 15 to 17,000,000 IU/ml while HBsAg quantification ranged from 0.25 to45,520 IU/ml. There was no statistically significant relationship between HDV-Ag and age (p = .51), sex (p = .73), HBV DNA (p = .8) and HBsAg quantification (p = 1).Conclusion: The prevalence of HDV-Ag among asymptomatic treatment naïve chronic hepatitis B patients in Abeokuta was 11% and there was no significant difference in the levels of HBV DNA and HBsAg among those with or without hepatitis D.

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.

Small hepatitis delta antigen selectively binds to target mRNA in hepatic cells: a potential mechanism by which hepatitis D virus downregulates glutathione S-transferase P1 and induces liver injury and hepatocarcinogenesis

Liver coinfection by hepatitis B virus (HBV) and hepatitis D virus (HDV) can result in a severe form of hepatocellular carcinoma with poor prognosis. Coinfection with HDV and HBV causes more deleterious effects than infection with HBV alone. Clinical research has shown that glutathione S-transferase P1 (GSTP1), a tumor suppressor gene, is typically downregulated in liver samples from hepatitis-infected patients. In the present study, our data indicated that small HDV antigen (s-HDAg) could specifically bind to GSTP1 mRNA and significantly downregulate GSTP1 protein expression. For the human fetal hepatocyte cell line L-02, cells transfected with s-HDAg, along with decreased GSTP1 expression, there was a significant accumulation of reactive oxygen species (ROS) and increased apoptotic ratios. Restoring GSTP1 expression through silencing s-HDAg via RNAi or overexpressing exogenous GSTP1 could largely recover the abnormal cell status. Our results revealed a novel potential mechanism of HDV-induced liver injury and hepatocarcinogenesis: s-HDAg can inhibit GSTP1 expression by directly binding to GSTP1 mRNA, which leads to accumulation of cellular ROS, resulting in high cellular apoptotic ratios and increased selective pressure for malignant transformation. To our knowledge, this is the first study to examine s-HDAg-specific pathogenic mechanisms through potential protein-RNA interactions.

Chronic hepatitis B and D: prognosis according to Child-Pugh score

Objective:

compare chronic hepatitis B patients to those superinfected with hepatitis D virus, according to Child-Pugh score regarding disease severity.

Method:

retrospective descriptive study, performed with 59 patients followed in the ambulatory, of which 22 (37.3%) were chronically infected with hepatitis B virus (Group HBV) and 37 (62.7%) superinfected with Delta virus (Group HBV+HDV); variables of sex, age and items of Child-Pugh score were collected by consulting medical records.

Results:

out of the patients, 57.6% were male, with a mean age of 30.5 years. Score A, which indicates lesser severity, was found in 100% of group HBV and 78.4% of group HBV+HDV. Score B, which indicates greater severity, was found only in group HBV+HDV in 21.6% of the patients.

Conclusion:

by means of the Child-Pugh score, it was observed that patients with superinfection by HDV tended to present a worse prognosis.

Objetivo:

comparar os pacientes com hepatite B crônica com superinfectados pelo vírus D segundo escore de Child-Pugh quanto à gravidade da doença.

Método:

estudo descritivo retrospectivo, realizado com 59 pacientes acompanhados em ambulatório, sendo 22 (37,3%) cronicamente infectados pelo vírus da hepatite B (Grupo VHB) e 37 (62,7%) com superinfecção por vírus Delta (Grupo VHB+VHD); foram coletadas variáveis quanto ao sexo, idade e referentes ao escore de Child-Pugh por meio de consulta a prontuários.

Resultados:

entre os pacientes 57,6% era do sexo masculino, com idade média de 30,5 anos. O escore A, que indica menor gravidade, foi encontrado em 100% do grupo VHB e 78,4% do grupo VHB+VHD. O escore B, que indica maior gravidade, foi encontrado apenas no grupo VHB+VHD em 21,6% dos pacientes.

Conclusão:

por meio do escore de Child-Pugh, observou-se que os pacientes com superinfecção por VHD tendem a apresentar pior prognóstico.

Treatment of chronic hepatitis D with the entry inhibitor myrcludex B: First results of a phase Ib/IIa study

BACKGROUND & AIMS

The therapeutic option for patients with chronic hepatitis delta virus infection (CHD) is limited to interferon alpha with rare curative outcome. Myrcludex B is a first-in-class entry inhibitor inactivating the hepatitis B virus (HBV) and hepatitis D virus (HDV) receptor sodium taurocholate co-transporting polypeptide. We report the interim results of a pilot trial on chronically infected HDV patients treated with myrcludex B, or pegylated interferon alpha (PegIFNα-2a) or their combination.

METHODS

Twenty-four patients with CHD infection were equally randomized (1:1:1) to receive myrcludex B, or PegIFNα-2a or their combination. Patients were evaluated for virological and biochemical response and tolerability of the study drugs at weeks 12 and 24.

RESULTS

Myrcludex B was well tolerated and no serious adverse event occurred. Although hepatitis B surface antigen levels remained unchanged, HDV RNA significantly declined at week 24 in all cohorts. HDV RNA became negative in two patients each in the Myrcludex B and PegIFNα-2a cohorts, and in five patients of the Myrcludex B+PegIFNα-2a cohort. ALT decreased significantly in the Myrcludex B cohort (six of eight patients), and HBV DNA was significantly reduced at week 24 in the Myrcludex B+PegIFNα-2a cohort. Virus kinetic modeling suggested a strong synergistic effect of myrcludex B and PegIFNα-2a on both HDV and HBV.

CONCLUSIONS

Myrcludex B showed a strong effect on HDV RNA serum levels and induced ALT normalization under monotherapy. Synergistic antiviral effects on HDV RNA and HBV DNA in the Myr-IFN cohort indicated a benefit of the combination of entry inhibition with PegIFNα-2a to treat CHD patients.

LAY SUMMARY

Myrcludex B is a new drug to treat hepatitis B and D infection. After 24weeks of treatment with myrcludex B and/or pegylated interferon α-2a, HDV R NA, a relevant marker for hepatitis D infection, decreased in all patients with chronic hepatitis B and D. Two of eight patients which received either myrcludex B or pegylated interferon α-2a, became negative for HDV RNA, and five of seven patients who received both drugs at the same time became negative. The drug was well tolerated.

Molecular epidemiology of hepatitis D virus circulating in Southwestern Nigeria

Background

Hepatitis B virus (HBV) and hepatitis D virus (HDV) infections are major public health problems in sub-Saharan Africa. Whereas it is known that HBV infection is endemic in Nigeria, there is only little data about HDV prevalence available. Here, we assessed the HDV seroprevalence and determined the HDV and HBV genotypes distribution among HBsAg positive individuals in Southwestern Nigeria.

Methods

This cross-sectional study involved 188 serum samples from HBsAg positive outpatients recruited at four tertiary hospitals in Southwestern Nigeria. Anti-HDV antibodies were detected by ELISA while HDV-RNA was detected by RT-PCR. Sequencing followed by phylogenetic analyses and HBV genotype-specific PCR were used to characterize HDV and HBV genotypes, respectively.

Results

Out of 188 HBsAg positive serum samples, 17 (9 %) showed detectable HDV-RNA. Anti-HDV antibodies test was possible from 103 samples and were observed in 4.9 % (5/103) patients. There was no significant difference in HDV prevalence between four main cities across the country. 64.7 % of HDV-RNA positive samples were from males and 35.3 % from females (P < 0.05). No significant associations were observed with regard to HDV seroprevalence and available demographic factors. Phylogenetic analyses demonstrated a predominance of HDV genotype 1 and HBV genotype E among the HDV-RNA/HBsAg positive patients.

Conclusions

In conclusion, our study showed a high prevalence of HDV infection in HBsAg carriers and the predominance of HDV genotype 1 infection in Nigerian HBV endemic region. The findings contribute to a better understanding of the relevance of HDV/HBV co-infection and circulating genotypes.

Hepatitis D Virus Infection Among Hepatitis B Surface Antigen Carriers and in "Isolated anti-HBc" Antibodies Profile in Central Tunisia

BACKGROUND

Hepatitis D Virus (HDV) causes accelerated liver diseases in patients with Hepatitis B Virus (HBV) infection. There is lack of data about its prevalence, related risk factors and interaction with HBV carriers in our country.

OBJECTIVES

The aim of this study was to estimate the prevalence of hepatitis delta and associated risk factors among Hepatitis B surface antigen (HBsAg) and "isolated anti-HBc" profile carriers in central Tunisia.

PATIENTS AND METHODS

In this cross-sectional study, 540 patients with positive HBsAg and 109 "isolated anti-HBc" profile receiving care in a teaching hospital were tested for the presence of HDV serum-markers using commercially available enzyme immunoassay kit. HBV-DNA was detected by nested PCR in "isolated anti-HBc" profile group.

RESULTS

Prevalence of HDV was 8.1% in HBsAg carriers group, but it was significantly higher in active than inactive hepatitis (30.2% and 4.5%, respectively, OR = 9, 95% CI: [4.48-18.58]). There was no significant association between studied risk factors and HDV infection. In the "isolated anti-HBc" profile group, prevalence of HDV was 4.6% and HBV-DNA had negative result in all patients with positive results for HDV.

CONCLUSIONS

Although HDV had low prevalence in our area, it is vital to plan preventive strategies for HDV spread as well as HBV prevention. It is particularly important to suspect HDV infection in active HBV carriers to manage a particularly severe dual infection. HDV infection should be suspected even in negative HBsAg patients having "isolated anti-HBc" profile.

Hepatitis B and Delta Virus: Advances on Studies about Interactions between the Two Viruses and the Infected Hepatocyte

The mechanisms determining persistence of hepatitis B virus (HBV) infection and long-term pathogenesis of HBV-associated liver disease appear to be multifactorial. Although viral replication can be efficiently suppressed by the antiviral treatments currently available, viral clearance is generally not achieved since HBV has developed unique replication strategies, enabling persistence of its genome within the infected hepatocytes. Moreover, no direct antiviral therapy exists for the more than 15 million people worldwide that are also coinfected with the hepatitis delta virus (HDV), a defective virus that needs the HBV envelope proteins for propagation. The limited availability of robust HBV and HDV infection systems has hindered the understanding of the complex network of virus-virus and virus-host interactions that are established in the course of infection and slowed down progress in drug development. Since chronic HBV/HDV coinfection leads to the most severe form of chronic viral hepatitis, elucidation of the molecular mechanisms regulating virus-host interplay and pathogenesis are urgently needed. This article summarizes the current knowledge regarding the interactions among HBV, HDV, and the infected target cell and discusses the dependence of HDV on HBV activity and possible future therapeutic approaches.

Molecular interactions between hepatitis B virus and delta virus

As a deficient virus due to the lack of envelope proteins, hepatitis D virus (HDV) causes chronic or fulminant “delta hepatitis” only in people with simultaneous hepatitis B virus (HBV) infection. HBV encodes three types of surface proteins known as small (S), medium (M) and large (L) envelope proteins. All three types of HBV surface antigens (HBsAgs) are present on HDV virions. The envelopment process of HDV occurs through interactions between the HDV ribonucleoprotein (RNP) complex and HBV HBsAgs. While HBsAg is the only protein required by HDV, the exact interaction sites between the S protein and pre-mature HDV are not well defined yet. In fact, these sites are distributed along the S protein with some hot spots for the envelopment process. Moreover, in most clinically studied samples, HDV infection is associated with a dramatically reduced HBV viral load, temporarily or permanently, while HBsAg resources are available for HDV packaging. Thus, beyond interacting with HBV envelope proteins, controlling mechanisms exist by which HDV inhibits HBV-DNA replication while allowing a selective transcription of HBV proteins. Here we discuss the molecular interaction sites between HBsAg and the HDV-RNP complex and address the proposed indirect mechanisms, which are employed by HBV and HDV to facilitate or inhibit each other’s viral replication. Understanding molecular interactions between HBV and HDV may help to design novel therapeutic strategies for delta hepatitis.

Hepatitis B virus epidemiology

The epidemiology of hepatitis B virus (HBV) infection is geographically diverse, with population prevalence, age and mode of acquisition, and likelihood of progression to chronic infection mutually interdependent. The burden of chronic HBV infection is increasingly being recognized, with cirrhosis and liver cancer attributable to HBV continuing to increase. The outcomes of chronic HBV infection are affected by a range of factors, including viral genotype, the presence of coinfections with other blood-borne viruses, and the impact of other causes of liver disease. The increased recognition of HBV infection as a leading cause of death globally has resulted in the development of new structures and policies at the international level; immediate attention to implementing these strategies is now required.

Efficacy of prolonged tenofovir therapy on hepatitis delta in HIV-infected patients

BACKGROUND

Hepatitis delta virus (HDV) produces the most severe form of chronic viral hepatitis. We explored whether prolonged tenofovir exposure might be beneficial on hepatitis delta in HIV-infected patients.

METHODS

All HIV-infected patients with hepatitis delta followed at our institution since year 2000 were retrospectively examined. Serum HBV-DNA and HDV-RNA were quantified using commercial assays. Liver fibrosis was measured using elastometry.

RESULTS

A total of 19 HIV/delta patients were identified. All were viremic for HDV and 11 for HBV. After a median tenofovir exposure of 58 months, all had undetectable HBV-DNA and 10 (53%) had undetectable HDV-RNA. The median drop in HDV-RNA in the remaining nine HDV viremic patients at the end of follow-up was 2.4 log copies/ml. A reduction above 30% in liver stiffness occurred in six out 10 (60%) patients who achieved undetectable HDV-RNA, whereas hepatic stiffness did not change in the remaining HDV viremic patients (P = 0.03). Serum HBsAg concentrations did not decline significantly, although HBsAg seroclearance occurred in three patients, all of whom became negative for HDV-RNA.

CONCLUSION

Long-term exposure to tenofovir significantly reduced serum HDV-RNA apart from completely suppressing HBV-DNA in HIV-infected patients with hepatitis delta. This virological benefit is accompanied by significant improvements in liver fibrosis.

Relevance of a full-length genomic RNA standard and a thermal-shock step for optimal hepatitis delta virus quantification

Hepatitis D virus (HDV) is a defective RNA virus that requires the surface antigens of hepatitis B virus (HBV) (HBsAg) for viral assembly and replication. Several commercial and in-house techniques have been described for HDV RNA quantification, but the methodologies differ widely, making a comparison of the results between studies difficult. In this study, a full-length genomic RNA standard was developed and used for HDV quantification by two different real-time PCR approaches (fluorescence resonance energy transfer [FRET] and TaqMan probes). Three experiments were performed. First, the stability of the standard was determined by analyzing the effect of thawing and freezing. Second, because of the strong internal base pairing of the HDV genome, which leads to a rod-like structure, the effect of intense thermal shock (95°C for 10 min and immediate cooling to -80°C) was tested to confirm the importance of this treatment in the reverse transcription step. Lastly, to investigate the differences between the DNA and RNA standards, the two types were quantified in parallel with the following results: the full-length genomic RNA standard was stable and reliably mimicked the behavior of HDV-RNA-positive samples, thermal shock enhanced the sensitivity of HDV RNA quantification, and the DNA standard underquantified the HDV RNA standard. These findings indicate the importance of using complete full-length genomic RNA and a strong thermal-shock step for optimal HDV RNA quantification.

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.

Treatment options for hepatitis delta virus infection

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

Molecular and clinical aspects of hepatitis D virus infections

Hepatitis D virus (HDV) is a defective virus with circular, single-stranded genomic RNA which needs hepatitis B virus (HBV) as a helper virus for virion assembly and infectivity. HDV virions are composed of a circular shape HDV RNA and two types of viral proteins, small and large HDAgs, surrounded by HBV surface antigen (HBsAg). The RNA polymerase II from infected hepatocytes is responsible for synthesizing RNAs with positive and negative polarities for HDV, as the virus does not code any enzyme to replicate its genome. HDV occurs as co-infection or super-infection in up to 5% of HBsAg carriers. A recent multi-center study highlighted that pegylated interferon α-2a (PEG-IFN) is currently the only treatment option for delta hepatitis. Nucleotide/nucleoside analogues, which are effective against HBV, have no relevant effects on HDV. However, additional clinical trials combining PEG-IFN and tenofovir are currently ongoing. The molecular interactions between HDV and HBV are incompletely understood. Despite fluctuating patterns of HBV viral load in the presence of HDV in patients, several observations indicate that HDV has suppressive effects on HBV replication, and even in triple infections with HDV, HBV and HCV, replication of both concomitant viruses can be reduced. Additional molecular virology studies are warranted to clarify how HDV interacts with the helper virus and which key cellular pathways are used by both viruses. Further clinical trials are underway to optimize treatment strategies for delta hepatitis.

Standardized one-step real-time reverse transcription-PCR assay for universal detection and quantification of hepatitis delta virus from clinical samples in the presence of a heterologous internal-control RNA

As for other chronic viral diseases, quantification of hepatitis delta virus (HDV) loads may be useful for patient management. We describe a one-step quantitative reverse transcription-PCR assay that is reliable and automatable and meets the regulatory authorities' standards for accurate quantification of the major HDV genotypes. It includes an internal control and uses in vitro-transcribed RNAs as standards. Its linearity range is 500 to 1.7 × 10(11) copies/ml, its sensitivity is around 150 copies/ml, its repeatability is around 15%, and its reproducibility is below 0.25 log(10) copies/ml.

Anti-HDV immunoglobulin M testing in hepatitis delta revisited: correlations with disease activity and response to pegylated interferon-α2a treatment

BACKGROUND

The role of anti-HDV immunoglobulin M (IgM) testing in patients receiving pegylated interferon-α therapy for hepatitis delta is unknown. We performed anti-HDV IgM testing in a well defined cohort of HDV-infected patients who were treated with pegylated interferon-α2a plus adefovir, or either drug alone.

METHODS

Sera from 33 HDV-RNA-positive patients from the international HIDIT-1 trial were available for anti-HDV IgM testing (ETI-DELTA-IGMK-2 assay, DiaSorin, Saluggia, Italy) before therapy, at treatment weeks 24 and 48, and at 24 weeks after the end of treatment.

RESULTS

Anti-HDV IgM tested positive in 31 out of the 33 patients (94%) prior to treatment. HDV IgM levels correlated with histological inflammatory activity (r=0.51, P<0.01) and were higher in patients with alanine aminotransferase and γ-glutamyl transpeptidase levels above the median (P<0.05). Quantitative anti-HDV IgM values declined in patients responding to antiviral therapy, however anti-HDV IgM remained positive after treatment in the majority of virological responders.

CONCLUSIONS

We suggest that anti-HDV IgM testing might give additional useful information to determine disease activity in hepatitis delta and to predict treatment response to antiviral therapy with type I interferons. However, determination of anti-HDV IgM can not substitute HDV RNA testing, which remains the primary virological marker for response to therapy.

Hepatitis delta in HIV-infected individuals in Europe

BACKGROUND

Hepatitis delta virus (HDV) infection results in the most aggressive form of chronic viral hepatitis. There is scarce information about the prevalence, epidemiology, virological profile and natural history of hepatitis delta in HIV patients.

METHODS

From 16,597 HIV patients enrolled in EuroSIDA, 1319 (7.9%) have ever reported serum hepatitis B virus (HBV) surface antigen (HBsAg)-positive. At last follow-up, 1084 (6.5%) patients were HBsAg-positive. The HDV substudy was carried out in 422 individuals for whom stored sera were available at the time they were HBsAg-positive. Anti-HDV immunoglobulin G was assessed using a commercial enzyme immunoassay (EIA) and serum HDV-RNA was quantified using a real-time PCR method.

RESULTS

A total of 61 of 422 HBsAg-positive carriers were anti-HDV-positive (prevalence: 14.5%). Hepatitis delta predominated in intravenous drug users and for this reason in south and/or east Europe. Serum HDV-RNA was detectable in 87% of tested anti-HDV-positive patients, with a median titer of 1.76×10(7) copies/ml. Overall, delta hepatitis patients showed lower serum HBV-DNA than the rest of HBsAg-positive carriers, although the inhibitory effect of HDV on HBV replication was not recognized in HBV genotype D patients. Whereas HDV was not associated with progression to AIDS, it significantly influenced the risk of death.

CONCLUSION

The prevalence of anti-HDV in chronic HBsAg-positive/HIV carriers in EuroSIDA is 14.5%. Most of these patients exhibit detectable HDV viraemia. Viral interference between HBV and HDV is manifested in all but HBV genotype D carriers in whom overt coreplication of both viruses occurs which might result in enhanced liver damage. Overall, delta hepatitis increases the risk of liver-related deaths and overall mortality in HIV patients.

Interferon impedes an early step of hepatitis delta virus infection

Hepatitis delta virus (HDV) infects hepatocytes, the major cell type of the liver. Infection of the liver may be either transient or chronic. The prognosis for patients with chronic HDV infection is poor, with a high risk of cirrhosis and hepatocellular carcinoma. The best antiviral therapy is weekly administration for at least one year of high doses of interferon alpha. This efficacy of interferon therapy has been puzzling in that HDV replication in transfected cell lines is reported as insensitive to administration of interferon alpha or gamma. Similarly, this study shows that even when an interferon response was induced by transfection of poly(IC) into a cell line, HDV RNA accumulation was only modestly inhibited. However, when the HDV replication was initiated by infection of primary human hepatocytes, simultaneous addition of interferons alpha or gamma at 600 units/ml, a concentration comparable to that achieved in treated patients, the subsequent HDV RNA accumulation was inhibited by at least 80%. These interferon treatments were shown to produce significant time-dependent increases of host response proteins such as for Stat-1, phosphoStat-1, Mx1/2/3 and PKR, and yet interferon pretreatment of hepatocytes did not confer an increased inhibition of HDV replication over interferon treatment at the time of (or after) infection. These and other data support the interpretation that interferon action against HDV replication can occur and is largely mediated at the level of entry into primary human hepatocytes. Thus in vivo, the success of long-term interferon therapy for chronic HDV, may likewise involve blocking HDV spread by interfering with the initiation of productive infection of naïve hepatocytes.

Advances in hepatobiliary pathology: update for 2010

Recent publications on hepatology and hepatic pathology provide a wealth of new information on wideranging topics. Morphologic aspects of liver disease associated with hepatitis B and C viruses, autoimmune hepatitis, and HIV infection were addressed, as was the prevalent problem of nonalcoholic fatty liver disease. Advances in diagnosis and pathogenesis of primary biliary cirrhosis, primary sclerosing cholangitis, and the increasingly complex spectrum of IgG4 hepatobiliary diseases were also reported. The histologic and immunohistochemical features of the rare "calcifying nested stromal-epithelial tumor" of the liver were described in a 9-case series. For benign and malignant liver tumors, immunohistochemistry plays a major diagnostic role, and several recent studies demonstrate the value of immunostains in distinguishing between liver-cell adenoma and focal nodular hyperplasia.

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.