Rapid early HDV RNA decline in the peripheral blood but prolonged intrahepatic hepatitis delta antigen persistence after liver transplantation

Blocking viral entry with bulevirtide reduces the number of HDV-infected hepatocytes in human liver biopsies

BACKGROUND & AIMS

Bulevirtide (BLV) is a first-in-class entry inhibitor and the only approved treatment for patients chronically infected with HDV in Europe. We aimed to investigate the efficacy of BLV treatment in paired liver biopsies obtained at baseline and after 24 or 48 weeks of treatment.

METHODS

We performed a combined analysis of 126 paired liver biopsies derived from three clinical trials. In the phase II clinical trial MYR202, patients with chronic hepatitis D were randomised to receive 24 weeks of BLV at 2 mg, 5 mg or 10 mg/day. Patients in MYR203 (phase II) and MYR301 (phase III) received 48 weeks of BLV at 2 mg or 10 mg/day. Tenofovir disoproxil fumarate monotherapy or delayed treatment served as comparators. Virological parameters and infection-related host genes were assessed by qPCR and immunohistochemistry.

RESULTS

At week 24, median intrahepatic HDV RNA decline from baseline was 0.9Log10 with 2 mg (n = 7), 1.1Log10 with 5 mg (n = 5) and 1.4 Log10 with 10 mg (n = 7) of BLV. At week 48, median reductions were 2.2Log10 with 2 mg (n = 27) and 2.7Log10 with 10 mg (n = 37) of BLV, while HDV RNA levels did not change in the comparator arms. Notably, a drastic decline in the number of hepatitis delta antigen-positive hepatocytes and a concomitant decrease in transcriptional levels of inflammatory chemokines and interferon-stimulated genes was determined in all BLV-treatment arms. Despite the abundance of HBsAg-positive hepatocytes, replication and covalently closed circular DNA levels of the helper virus HBV were low and remained unaffected by BLV treatment.

CONCLUSION

Blocking viral entry diminishes signs of liver inflammation and promotes a strong reduction of HDV infection within the liver, thus suggesting that some patients may achieve HDV cure with long-term treatment.

IMPACT AND IMPLICATIONS

Chronic infection with HDV causes the most severe form of viral hepatitis, affecting approximately 12 million people worldwide. The entry inhibitor bulevirtide (BLV) is the only recently approved anti-HDV drug, which has proven efficacious and safe in clinical trials and real-word data. Here, we investigated paired liver biopsies at baseline and after 24 or 48 weeks of treatment from three clinical trials to understand the effect of the drug on viral and host parameters in the liver, the site of viral replication. We found that BLV treatment strongly reduces the number of HDV-infected cells and signs of liver inflammation. This data implies that blocking viral entry ameliorates liver inflammation and that prolonged treatment regimens might lead to HDV cure in some patients. This concept will guide the further development of therapeutic strategies and combination treatments for patients with CHD.

CLINICAL TRIAL NUMBERS

NCT03546621, NCT02888106, NCT03852719.

Hepatitis Delta Virus and Hepatocellular Carcinoma

The hepatitis D virus (HDV) is a compact, enveloped, circular RNA virus that relies on hepatitis B virus (HBV) envelope proteins to initiate a primary infection in hepatocytes, assemble, and secrete new virions. Globally, HDV infection affects an estimated 12 million to 72 million people, carrying a significantly elevated risk of developing cirrhosis, liver failure, and hepatocellular carcinoma (HCC) compared to an HBV mono-infection. Furthermore, HDV-associated HCC often manifests at a younger age and exhibits more aggressive characteristics. The intricate mechanisms driving the synergistic carcinogenicity of the HDV and HBV are not fully elucidated but are believed to involve chronic inflammation, immune dysregulation, and the direct oncogenic effects of the HDV. Indeed, recent data highlight that the molecular profile of HCC associated with HDV is unique and distinct from that of HBV-induced HCC. However, the question of whether the HDV is an oncogenic virus remains unanswered. In this review, we comprehensively examined several crucial aspects of the HDV, encompassing its epidemiology, molecular biology, immunology, and the associated risks of liver disease progression and HCC development.

Quantitative methods for optimizing patient outcomes in liver transplantation

Liver transplantation (LT) is a lifesaving yet complex intervention with considerable challenges impacting graft and patient outcomes. Despite best practices, 5-year graft survival is only 70%. Sophisticated quantitative techniques offer potential solutions by assimilating multifaceted data into insights exceeding human cognition. Optimizing donor-recipient matching and graft allocation presents additional intricacies, involving the integration of clinical and laboratory data to select the ideal donor and recipient pair. Allocation must balance physiological variables with geographical and logistical constraints and timing. Quantitative methods can integrate these complex factors to optimize graft utilization. Such methods can also aid in personalizing treatment regimens, drawing on both pretransplant and posttransplant data, possibly using continuous immunological monitoring to enable early detection of graft injury or infected states. Advanced analytics is thus poised to transform management in LT, maximizing graft and patient survival. In this review, we describe quantitative methods applied to organ transplantation, with a focus on LT. These include quantitative methods for (1) utilizing and allocating donor organs equitably and optimally, (2) improving surgical planning through preoperative imaging, (3) monitoring graft and immune status, (4) determining immunosuppressant doses, and (5) establishing and maintaining the health of graft and patient after LT.

The role of HBIG in real life for patients undergoing liver transplantation due to HDV-related cirrhosis

Recommended post-liver transplant (LT) prophylaxis in patients with hepatitis delta includes a nucleos(t)ide analogue (NA) and anti-hepatitis B immunoglobulin (HBIG) indefinitely. We analysed the use of HBIG in real-life clinical practice and its impact on HBV/HDV recurrence in 174 HDV-related LT patients from 10 Spanish liver transplant centres (1988-2018). Median post-LT follow-up was 7.8 (2.3-15.1) years and patient survival at 5 years was 90%. Most patients (97%) received HBIG in the immediate post-LT, but only 42% were on HBIG at the last control. Among those discontinuing HBIG, the median time on treatment was 18 (7-52) months. Post-LT HBsAg+ was detected in 16 (9%) patients and HBV-DNA in 12 (7%). Despite HBsAg positivity, HDV recurrence was reported only in three patients (1.7%), all of whom were not receiving NA and had discontinued HBIG. Our data suggest that a finite HBIG prophylaxis in HDV-LT is feasible, especially if high-barrier NAs are used.

The Circulating miRNA Profile of Chronic Hepatitis D and B Patients Is Comparable but Differs from That of Individuals with HBeAg-Negative HBV Infection

miRNAs circulating in whole serum and HBsAg-particles are differentially expressed in chronic hepatitis B (CHB) and HBeAg-negative-HBV infection (ENI); their profiles are unknown in chronic hepatitis D (CHD). Serum- and HBsAg-associated miRNAs were analyzed in 75 subjects of 3 well-characterized groups (CHB 25, CHD 25, ENI 25) using next-generation sequencing (NGS). Overall miRNA profiles were consonant in serum and HBsAg-particles but significantly different according to the presence of hepatitis independently of Hepatitis D Virus (HDV)-co-infection. Stringent (Bonferroni Correction < 0.001) differential expression analysis showed 39 miRNAs upregulated in CHB vs. ENI and 31 of them also in CHD vs. ENI. miRNA profiles were coincident in CHB and CHD with only miR-200a-3p upregulated in CHB. Three miRNAs (miR-625-3p, miR-142-5p, and miR-223-3p) involved in immune response were upregulated in ENI. All 3 hepatocellular miRNAs of MiR-B-Index (miR-122-5p, miR-99a-5p, miR-192-5p) were overexpressed in both CHB and CHD patients. In conclusion, CHD and CHB patients showed highly similar serum miRNA profiling that was significantly different from that of individuals with HBeAg-negative infection and without liver disease.

Triple Threat: HDV, HBV, HIV Coinfection

Hepatitis delta virus (HDV) only infects patients with hepatitis B virus (HBV) due to its reliance on HBV surface proteins to form its envelope. With shared routes of transmission, HDV coinfection is estimated to occur in 15% of patients with HIV and HBV. However, HDV is often underdiagnosed and may be missed particularly in people living with HIV (PLWH) who are already on antiretroviral therapy with anti-HBV activity and coincidental HBV suppression. At the same time, HDV causes the most severe form of chronic viral hepatitis and leads to faster progression of liver disease and hepatocellular carcinoma. Thus, increased recognition and effective treatment are paramount, and as novel treatment options approach global markets, the study of their efficacy in PLWH should be pursued.

Hepatitis delta: Epidemiology to recent advances in therapeutic agents

Hepatitis D virus (HDV) was first described in 1977 and is dependent on the presence of hepatitis B surface antigen (HBsAg) for its entry into cells and on the human host for replication. Due to the envelopment with the hepatitis B virus (HBV) envelope, early phases of HDV entry resemble HBV infection. Unlike HBV, HDV activates innate immune responses. The global prevalence of HDV is estimated to be about 5% of HBsAg positive individuals. However, recent studies have described a wide range of prevalence between 12 to 72 million individuals. Infection can occur as super-infection or co-infection. The diagnosis of active HDV infection involves screening with anti HDV antibodies followed by quantitative PCR testing for HDV RNA in those who are HBsAg positive. The diagnostic studies have evolved over the years improving the validity and reliability of the tests performed. HDV infection is considered the most severe form of viral hepatitis and the HDV genotype may influence the disease course. There are eight major HDV genotypes with prevalence varying by geographic region. HDV treatment has been challenging as HDV strongly depends on the host cell for replication and provides few, if any viral targets. Better understanding of HDV virology has led to the development of several therapeutic agents currently being studied in different phase II and III clinical trials. There is increasing promise of effective therapies that will ameliorate the course of this devastating disease.

Interferon-based treatment of chronic hepatitis D

Treatment of hepatitis D virus (HDV) infection has been based on the administration of interferon-alfa for more than three decades. First studies to treat HDV-infected patients with type 1 interferons were already performed in the 1980s. Several smaller trials and case series were reported thereafter. During the mid 2000s the use of pegylated interferons for hepatitis D was established. Since then, additional trials were performed in different countries exploring strategies to personalize treatment including extended treatment durations. The overall findings were that about one-quarter to one-third of patients benefit from interferon treatment with persistent suppression of HDV replication. However, only few patients achieve also functional cure of hepatitis B with HBsAg loss. Importantly, several studies indicate that successful interferon treatment is associated with improved clinical long-term outcomes. Still, only a proportion of patients with hepatitis D can be treated with interferons. Even though alternative treatments are currently developed, it is likely that pegylated interferon-alfa will still have an important role in the management of hepatitis D - either alone or in combination. Therefore, better biomarkers are needed to select patients with a high likelihood to benefit from interferon-based treatments. In this review we are discussing basic principles of mode of action of interferon alpha against HDV, summarize previous data on interferon treatment of hepatitis D and give an outlook on potential combinations with novel drugs currently in development.

EASL Clinical Practice Guidelines on hepatitis delta virus

Hepatitis D virus (HDV) is a defective virus that requires the hepatitis B virus to complete its life cycle and cause liver damage in humans. HDV is responsible for rare acute and chronic liver diseases and is considered the most aggressive hepatitis virus. Acute infection can cause acute liver failure, while persistent infection typically causes a severe form of chronic hepatitis which is associated with rapid and frequent progression to cirrhosis and its end-stage complications, hepatic decompensation and hepatocellular carcinoma. Major diagnostic and therapeutic innovations prompted the EASL Governing Board to commission specific Clinical Practice Guidelines on the identification, virologic and clinical characterisation, prognostic assessment, and appropriate clinical and therapeutic management of HDV-infected individuals.

Immunology of hepatitis D virus infection: General concepts and present evidence

Infection with the hepatitis D virus induces the most severe form of chronic viral hepatitis, affecting over 12 million people worldwide. Chronic HDV infection leads to rapid development of liver cirrhosis and hepatocellular carcinoma in ~70% of patients within 15 years of infection. Recent evidence suggests that an interplay of different components of the immune system are contributing to viral control and may even be implicated in liver disease pathogenesis. This review will describe general concepts of antiviral immune response and elicit the present evidence concerning the interplay of the hepatitis D virus with the immune system.

Novel concepts on mechanisms underlying Hepatitis Delta virus persistence and related pathogenesis

Hepatitis Delta virus is the smallest known human virus, exploiting the HBV surface proteins (HBsAg) for the release of its progeny and de novo entry into hepatocytes. Ever growing evidence have highlighted the existence of multiple mechanisms underlying HDV persistence including integrated HBV-DNA as a source of HBsAg production and the capability of the HDV genome to propagate through cell proliferation, thus supporting a potential HDV persistence even in the absence of HBV. Chronic HDV-infection causes the most severe form of viral hepatitis, leading to the development of cirrhosis in 15% of cases within 1-2 years and in 50%-60% of cases within 5-10 years. The rates of hepatocellular carcinoma and hepatic decompensation are also 2-3-fold higher than for HBV mono-infection. There is the evidence that persistent viral replication plays a key role in triggering liver injury, suggesting the existence of direct viral cytopathic properties that can modulate, synergistically with immune-responses, the progression towards end-stage liver diseases. All these aspects can be further exacerbated by the extraordinary degree of viral genetic variability that can promote HDV evasion from immune responses and has enabled viral differentiation into genotypes and subgenotypes with potential different pathobiological properties. In this light, this review aims at providing comprehensive insights of mechanisms (with a focus on virological factors) underlying HDV persistence and pathogenesis, critical in shaping the clinical outcome of the infection. Dissecting these mechanisms is pivotal to optimize therapeutic strategies aimed at fully counteracting this fascinating and fearsome virus.

Viral Diagnosis of Hepatitis B and Delta: What We Know and What Is Still Required? Specific Focus on Low- and Middle-Income Countries

To achieve the World Health Organization's (WHO) goals of eradicating viral hepatitis globally by 2030, the regional prevalence and epidemiology of hepatitis B virus (HBV) and hepatitis delta virus (HDV) coinfection must be known in order to implement preventiveon and treatment strategies. HBV/HDV coinfection is considered the most severe form of vira l hepatitis due to it's rapid progression towards cirrhosis, hepatocellular carcinoma, and liver-related death. The role of simplified diagnosticsis tools for screening and monitoring HBV/HDV-coinfected patients is crucial. Many sophisticated tools for diagnoses have been developed for detection of HBV alone as well as HBV/HDV coinfection. However, these advanced techniques are not widely available in low-income countries and there is no standardization for HDV detection assays, which are used for monitoring the response to antiviral therapy. More accessible and affordable alternative methods, such as rapid diagnostic tests (RDTs), are being developed and validated for equipment-free and specific detection of HBV and HDV. This review will provide some insight into both existing and diagnosis tools under development, their applicability in developing countries and how they could increase screening, patient monitoring and treatment eligibility.

Hepatitis D virus-induced interferon response and administered interferons control cell division-mediated virus spread

BACKGROUND & AIMS

Besides HBV-dependent de novo infection, cell division-mediated spread contributes to HDV persistence and dampens the effect of antivirals that abrogate de novo infection. Nonetheless, the combination of these antivirals with interferons (IFNs) showed strong synergism in recent clinical trials, implying a complementary mode-of-action of IFNs. Therefore, we investigated the effect of IFN response on cell division-mediated HDV spread.

METHODS

Cells infected with HDV were passaged to undergo cell division. The effect of the IFN response was evaluated by blocking HDV-induced IFN activation, by applying different IFN treatment regimens, and by adjusting HDV infection doses.

RESULTS

Cell division-mediated HDV spread was highly efficient following infection of HuH7^NTCP cells (defective in IFN production), but profoundly restricted in infected IFN-competent HepaRG^NTCP cells. Treatment with IFN-α/-λ1 inhibited HDV spread in dividing HuH7^NTCP cells, but exhibited a marginal effect on HDV replication in resting cells. Blocking the HDV-induced IFN response with the JAK1/2 inhibitor ruxolitinib or knocking down MDA5 augmented HDV spread in dividing HepaRG^NTCP cells. The virus-induced IFN response also destabilized HDV RNA in dividing cells. Moreover, the effect of exogenous IFNs on cell division-mediated HDV spread was more pronounced at low multiplicities of infection with weak virus-induced IFN responses.

CONCLUSIONS

Both HDV-induced IFN response and exogenous IFN treatment suppress cell division-mediated HDV spread, presumably through acceleration of HDV RNA decay. Our findings demonstrate a novel mode-of-action of IFN, explain the more pronounced effect of IFN therapy in patients with lower HDV serum RNA levels, and provide insights for the development of combination therapies.

LAY SUMMARY

Chronic hepatitis D is a major health problem. The causative pathogen hepatitis D virus (HDV) can propagate through viral particle-mediated infection and the division of infected cells. Although viral particle-dependent infection can be blocked by recently developed drugs, therapies addressing the cell division route have not been reported. Taking advantage of relevant cell culture models, we demonstrate that the widely used immune modulator interferon can efficiently suppress HDV spread through cell division. This work unveils a new function of interferon and sheds light on potentially curative combination therapies.

New Treatments for Chronic Hepatitis B Virus/Hepatitis D Virus Infection

Chronic hepatitis D virus (HDV) infection is the most severe form of viral hepatitis with high rates of end-stage liver disease and hepatocellular carcinoma. Therefore, effective antiviral treatment strategies are needed desperately. Until recently, antiviral treatment was limited to pegylated interferon-alpha. With the conditional approval of the entry inhibitor bulevirtide by the European Medicines Agency, new treatment options are now available. In addition, multiple other antiviral compounds are currently tested in clinical phase II and III trials and represent promising agents for the treatment of chronic HDV infection.

2020 position statement and recommendations of the European Liver and Intestine Transplantation Association (ELITA): management of hepatitis B virus-related infection before and after liver transplantation

BACKGROUND

Prophylaxis of HBV recurrence is critical after liver transplantation in HBV patients. Despite new prophylactic schemes, most European LT centres persist on a conservative approach combining hepatitis B immunoglobulin (HBIG) and nucleos(t)ides analogues (NA).

AIM

This setting prompted the European Liver Intestine Transplantation Association (ELITA) to look for a consensus on the prevention of HBV recurrence.

METHODS

Based on a 4-round Delphi process, ELITA investigated 16 research questions and established 50 recommendations.

RESULTS

Prophylaxis should be driven according to 3 simplified risk groups: Low and high virological risk patients, with undetectable and detectable HBV DNA pre-LT, respectively, and special populations (HDV, HCC, poorly adherent patients). In low-risk patients, short-term (4 weeks) combination of third-generation NA+ HBIG, or third generation NA monotherapy can be considered as prophylactic options. In high-risk patients, HBIG can be discontinued once HBV DNA undetectable. Combined therapy for 1 year is advised. HBV-HCC patients should be treated according to their virological risk. In HDV/HBV patients, indefinite dual prophylaxis remains the gold standard. Full withdrawal of HBV prophylaxis following or not HBV vaccination should only be attempted in the setting of clinical trials. Organs from HBsAg+ve donors may be considered after assessment of risks, benefits, and patient consent. They should not be used if HDV is present. In poorly adherent patients, dual long-term prophylaxis is recommended. Budget impact analysis should be taken into account to drive prophylactic regimen.

CONCLUSIONS

These ELITA recommendations should stimulate a more rational and homogeneous approach to HBV prophylaxis across LT programs.

Hepatitis D virus in 2021: virology, immunology and new treatment approaches for a difficult-to-treat disease

Approximately 5% of individuals infected with hepatitis B virus (HBV) are coinfected with hepatitis D virus (HDV). Chronic HBV/HDV coinfection is associated with an unfavourable outcome, with many patients developing liver cirrhosis, liver failure and eventually hepatocellular carcinoma within 5-10 years. The identification of the HBV/HDV receptor and the development of novel in vitro and animal infection models allowed a more detailed study of the HDV life cycle in recent years, facilitating the development of specific antiviral drugs. The characterisation of HDV-specific CD4+ and CD8+T cell epitopes in untreated and treated patients also permitted a more precise understanding of HDV immunobiology and possibly paves the way for immunotherapeutic strategies to support upcoming specific therapies targeting viral or host factors. Pegylated interferon-α has been used for treating HDV patients for the last 30 years with only limited sustained responses. Here we describe novel treatment options with regard to their mode of action and their clinical effectiveness. Of those, the entry-inhibitor bulevirtide (formerly known as myrcludex B) received conditional marketing authorisation in the European Union (EU) in 2020 (Hepcludex). One additional drug, the prenylation inhibitor lonafarnib, is currently under investigation in phase III clinical trials. Other treatment strategies aim at targeting hepatitis B surface antigen, including the nucleic acid polymer REP2139Ca. These recent advances in HDV virology, immunology and treatment are important steps to make HDV a less difficult-to-treat virus and will be discussed.

Antiviral prophylaxis against hepatitis B recurrence after liver transplantation: Current concepts

The advance in treatment against hepatitis B virus (HBV) infection with the development of nucleos(t)ide analogues (NAs) with high genetic barrier to resistance, including entecavir and tenofovir, has improved clinical outcomes of patients transplanted for HBV infection, by preventing HBV recurrence after liver transplantation (LT) effectively. Currently, after LT, the combination of hepatitis B immunoglobulin (HBIG) and a high-barrier NA is considered as the standard of care for prophylaxis against HBV recurrence. However, because of the high cost of intravenous high-dose HBIG, other routes of HBIG administration, such as intramuscular or subcutaneous, have come to the foreground. In addition, several transplant centres tend to use a NA as monoprophylaxis, following a short post-LT period of HBIG and NA combination. Lately, studies using HBIG-free prophylactic regimens with entecavir or tenofovir have shown promising outcomes in preventing HBV recurrence, mostly regarding patients with undetectable HBV DNA at the time of LT. Although vaccination against HBV has been an attractive prophylactic approach, its efficacy has been controversial. Moreover, further studies are needed regarding long-term outcomes of complete withdrawal anti-HBV prophylaxis. For patients transplanted for HBV/HDV co-infection, combined regimen should be administered for a longer period post-LT. Finally, the use of grafts from hepatitis B core antibody-positive donors is safe for HBV-negative recipients, with the administration of lifelong antiviral prophylaxis.

Hepatitis Delta Virus (HDV) and Delta-Like Agents: Insights Into Their Origin

Hepatitis delta virus (HDV) is a human pathogen, and the only known species in the genus Deltavirus. HDV is a satellite virus and depends on the hepatitis B virus (HBV) for packaging, release, and transmission. Extracellular HDV virions contain the genomic HDV RNA, a single-stranded negative-sense and covalently closed circular RNA molecule, which is associated with the HDV-encoded delta antigen forming a ribonucleoprotein complex, and enveloped by the HBV surface antigens. Replication occurs in the nucleus and is mediated by host enzymes and assisted by cis-acting ribozymes allowing the formation of monomer length molecules which are ligated by host ligases to form unbranched rod-like circles. Recently, meta-transcriptomic studies investigating various vertebrate and invertebrate samples identified RNA species with similarities to HDV RNA. The delta-like agents may be representatives of novel subviral agents or satellite viruses which share with HDV, the self-complementarity of the circular RNA genome, the ability to encode a protein, and the presence of ribozyme sequences. The widespread distribution of delta-like agents across different taxa with considerable phylogenetic distances may be instrumental in comprehending their evolutionary history by elucidating the transition from transcriptome to cellular circular RNAs to infectious subviral agents.

Innate immunity in hepatitis B and D virus infection: consequences for viral persistence, inflammation, and T cell recognition

Chronic infections with human hepatitis viruses continue to be a major health burden worldwide. Despite the availability of an effective prophylactic vaccine against the hepatitis B virus (HBV) and of antiviral agents efficiently suppressing HBV replication, more than 250 million people are currently chronically infected with this hepatotropic DNA virus, and resolution of chronic hepatitis B (CHB) is rarely achieved. Moreover, coinfection with the hepatitis D virus (HDV), a human RNA satellite virus requiring the envelope proteins of HBV for productive viral spreading, substantially aggravates the disease course of CHB. The molecular mechanisms by which these viruses interact with each other and with the intrinsic innate responses of the hepatocytes are not fully understood. While HBV appears to avoid innate immune recognition, HDV elicits a strong enhancement of innate responses. Notwithstanding, such induction does not hamper HDV replication but contributes to liver inflammation and pathogenesis. Intriguingly, HDV appears to influence the ability of T cells to recognize infected hepatocytes by boosting antigen presentation. This review focuses on current knowledge regarding how these viruses can shape and counteract the intrinsic innate responses of the hepatocytes, thus affecting the immune system and pathogenesis. Understanding the distinct strategies of persistence that HBV and HDV have evolved is central for advancing the development of curative therapies.

HDV Pathogenesis: Unravelling Ariadne's Thread

Hepatitis Delta virus (HDV) lies in between satellite viruses and viroids, as its unique molecular characteristics and life cycle cannot categorize it according to the standard taxonomy norms for viruses. Being a satellite virus of hepatitis B virus (HBV), HDV requires HBV envelope glycoproteins for its infection cycle and its transmission. HDV pathogenesis varies and depends on the mode of HDV and HBV infection; a simultaneous HDV and HBV infection will lead to an acute hepatitis that will resolve spontaneously in the majority of patients, whereas an HDV super-infection of a chronic HBV carrier will mainly result in the establishment of a chronic HDV infection that may progress towards cirrhosis, liver decompensation, and hepatocellular carcinoma (HCC). With this review, we aim to unravel Ariadne’s thread into the labyrinth of acute and chronic HDV infection pathogenesis and will provide insights into the complexity of this exciting topic by detailing the different players and mechanisms that shape the clinical outcome.

In Vivo Models of HDV Infection: Is Humanizing NTCP Enough?

The discovery of sodium taurocholate co-transporting polypeptide (NTCP) as a hepatitis B (HBV) and delta virus (HDV) entry receptor has encouraged the development of new animal models of infection. This review provides an overview of the different in vivo models that are currently available to study HDV either in the absence or presence of HBV. By presenting new advances and remaining drawbacks, we will discuss human host factors which, in addition to NTCP, need to be investigated or identified to enable a persistent HDV infection in murine hepatocytes. Detailed knowledge on species-specific factors involved in HDV persistence also shall contribute to the development of therapeutic strategies.

New insights into HDV persistence: The role of interferon response and implications for upcoming novel therapies

Chronic hepatitis D (CHD), a global health problem, manifests as the most severe form of viral hepatitis. The causative agent, HDV, is the smallest known human virus; it replicates its circular single-stranded RNA genome in the nucleus of hepatocytes. HDV requires HBV-encoded envelope proteins for dissemination and de novo cell entry. However, HDV can also spread through cell division. Following entry into hepatocytes, replicative intermediates of HDV RNA are sensed by the pattern recognition receptor MDA5 (melanoma differentiation antigen 5) resulting in interferon (IFN)-β/λ induction. This IFN response strongly suppresses cell division-mediated spread of HDV genomes, however, it only marginally affects HDV RNA replication in already infected, resting hepatocytes. Monotherapy with IFN-α/λ shows efficacy but rarely results in HDV clearance. Recent molecular insights into key determinants of HDV persistence and the accelerated development of specifically acting antivirals that interfere with the replication cycle have revealed promising new therapeutic perspectives. In this review, we briefly summarise our knowledge on replication/persistence of HDV, the newly discovered HDV-like agents, and the interplay of HDV with the IFN response and its consequences for persistence. Finally, we discuss the possible role of IFNs in combination with upcoming therapies aimed at HDV cure.

Murine hepatocytes do not support persistence of Hepatitis D virus mono-infection in vivo

BACKGROUNDS & AIMS

As a result of the limited availability of in vivo models for hepatitis D virus (HDV), treatment options for HDV chronically infected patients are still scant. The discovery of sodium taurocholate cotransporting polypeptide (NTCP) as HDV entry receptor has enabled the development of new infection models.

AIM

To comparatively assess the efficacy and persistence of HDV mono-infection in murine and human hepatocytes in vivo.

METHODS

Mice with humanized NTCP (hNTCP^ed84-87 mice) were generated by editing amino acid residues 84-87 of murine NTCP in C57BL/6J mice. HDV infection was assessed in hNTCP^ed84-87 mice and in immune deficient uPA/SCID/beige (USB) mice, whose livers were reconstituted with human or murine (hNTCP^ed84-87 ) hepatocytes. Livers were analysed between 5 and 42 days post-HDV inoculation by qRT-PCR, immunofluorescence and RNA in situ hybridization (ISH).

RESULTS

hNTCP^ed84-87 mice could be infected with HDV genotype 1 or 3. ISH analysis demonstrated the presence of antigenomic HDV RNA positive murine hepatocytes with both genotypes, proving initiation of HDV replication. Strikingly, murine hepatocytes cleared HDV within 21 days both in immunocompetent hNTCP^ed84-87 mice and in immunodeficient USB mice xenografted with murine hepatocytes. In contrast, HDV infection remained stable for at least 42 days in human hepatocytes. Intrinsic innate responses were not enhanced in any of the HDV mono-infected cells and livers.

CONCLUSION

These findings suggest that in addition to NTCP, further species-specific factors limit HDV infection efficacy and persistence in murine hepatocytes. Identifying such species barriers may be crucial to develop novel potential therapeutic targets of HDV.

Interplay between Hepatitis D Virus and the Interferon Response

Chronic hepatitis D (CHD) is the most severe form of viral hepatitis, with rapid progression of liver-related diseases and high rates of development of hepatocellular carcinoma. The causative agent, hepatitis D virus (HDV), contains a small (approximately 1.7 kb) highly self-pairing single-strand circular RNA genome that assembles with the HDV antigen to form a ribonucleoprotein (RNP) complex. HDV depends on hepatitis B virus (HBV) envelope proteins for envelopment and de novo hepatocyte entry; however, its intracellular RNA replication is autonomous. In addition, HDV can amplify HBV independently through cell division. Cellular innate immune responses, mainly interferon (IFN) response, are crucial for controlling invading viruses, while viruses counteract these responses to favor their propagation. In contrast to HBV, HDV activates profound IFN response through the melanoma differentiation antigen 5 (MDA5) pathway. This cellular response efficiently suppresses cell-division-mediated HDV spread and, to some extent, early stages of HDV de novo infection, but only marginally impairs RNA replication in resting hepatocytes. In this review, we summarize the current knowledge on HDV structure, replication, and persistence and subsequently focus on the interplay between HDV and IFN response, including IFN activation, sensing, antiviral effects, and viral countermeasures. Finally, we discuss crosstalk with HBV.

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 Delta: Prevalence, Natural History, and Treatment Options

Half a century after its discovery, hepatitis delta remains a pertinent global health issue with a major clinical impact in endemic regions and an underestimated prevalence worldwide. Hepatitis delta virus infection follows a challenging clinical course and is responsible for significant liver-related morbidity. Although the only currently available treatment (pegylated interferon) does not provide consistent results, emerging therapeutic options are promising. This article explores the epidemiology, natural history, as well as current and potential therapeutic options for hepatitis delta virus infection.

Post liver transplant recurrent and de novo viral infections

Survival following liver transplantation has changed dramatically owing to improvement in surgical techniques, peri-operative care and optimal immunosuppressive therapy. Post-Liver transplant (LT) de novo or recurrent viral infection continues to cause major allograft dysfunction, leading to poor graft and patient survival in untreated patients. Availability of highly effective antiviral drugs has significantly improved post-LT survival. Patients transplanted for chronic hepatitis B infection should receive life-long nucleos(t)ide analogues, with or without HBIg for effective viral control. Patients with chronic hepatitis C should be commenced on directly acting antiviral (DAA) drugs prior to transplantation. DAA therapy for post-LT recurrent hepatitis C infection is associated with close to 100% sustained virological response (SVR), irrespective of genotype. De novo chronic Hepatitis E infection is an increasingly recognised cause of allograft dysfunction in LT recipients. Untreated chronic HEV infection of the graft may lead to liver fibrosis and allograft failure. CMV and EBV can reactivate leading to systemic illness following liver transplantation. With COVID-19 pandemic, post-transplant patients are at risk of SARS-Co-V2 infection. Majority of the LT recipients require hospitalization, and the mortality in this population is around 20%. Early recognition of allograft dysfunction and identification of viral aetiology is essential in the management of post-LT de novo or recurrent infections. Optimising immunosuppression is an important step in reducing the severity of allograft damage in the treatment of post-transplant viral infections. Viral clearance or control can be achieved by early initiation of high potency antiviral therapy.

Within-host mathematical models of hepatitis B virus infection: Past, present, and future

Mathematical modeling has been instrumental in enhancing our understanding of the viral dynamics of hepatitis B virus (HBV) infection. We give a primer on HBV infection in humans and a brief overview of the development of within-host mathematical models of HBV infection. In the last decade, models have advanced from considering chronic HBV infections under therapy to the pathogenesis of infection. We also summarize estimates of key viral dynamic parameters that have varied greatly among studies, and show that they impact model predictions. Future directions for mathematical modeling of HBV infection are proposed to better understand emerging therapies, the HBV life cycle, predicting cure, and the mechanisms involved in the immune response to HBV infection.

The oncogenic role of hepatitis delta virus in hepatocellular carcinoma

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

Current state-of-the-art pharmacotherapy for the management of hepatitis B infection

INTRODUCTION

Hepatitis B virus (HBV) infection remains a global challenge with several hundred million infected individuals. Disease activity can be controlled, and adverse outcomes prevented when treatment can be provided. Frequently life-long therapy is required instead of defined treatment periods such as with the case of Hepatitis C Virus (HCV) infection.

AREAS COVERED

In this review, the authors provide an overview of current start of the art therapy for HBV and indicate where variation from the current guidelines could be considered. Certain patients may be eligible for treatment with suboptimal therapies when their baseline viral load is low. Identifying ideal candidates for interferon therapy will result in good sustained responses for some patients.

EXPERT OPINION

The biggest challenge remains linking patients to care and therapy. Patients can nowadays be sufficiently treated before the disease advances to a more progressed phase. However, future therapies must be extremely safe and ideally limit the required treatment period. Given Hepatitis D Virus's dependence on HBV and being a disease with an unmet clinical need, HDV may be the best target group for the development of a functional cure for hepatitis B.

Hepatitis delta virus persists during liver regeneration and is amplified through cell division both in vitro and in vivo

OBJECTIVE

Hepatitis delta virus (HDV) was shown to persist for weeks in the absence of HBV and for months after liver transplantation, demonstrating the ability of HDV to persevere in quiescent hepatocytes. The aim of the study was to evaluate the impact of cell proliferation on HDV persistence in vitro and in vivo.

DESIGN

Genetically labelled human sodium taurocholate cotransporting polypeptide (hNTCP)-transduced human hepatoma(HepG2) cells were infected with HBV/HDV and passaged every 7 days for 100 days in the presence of the entry inhibitor Myrcludex-B. In vivo, cell proliferation was triggered by transplanting primary human hepatocytes (PHHs) isolated from HBV/HDV-infected humanised mice into naïve recipients. Virological parameters were measured by quantitative real time polymerase chain reaction (qRT-PCR). Hepatitis delta antigen (HDAg), hepatitis B core antigen (HBcAg) and cell proliferation were determined by immunofluorescence.

RESULTS

Despite 15 in vitro cell passages and block of viral spreading by Myrcludex-B, clonal cell expansion permitted amplification of HDV infection. In vivo, expansion of PHHs isolated from HBV/HDV-infected humanised mice was confirmed 3 days, 2, 4 and 8 weeks after transplantation. While HBV markers rapidly dropped in proliferating PHHs, HDAg-positive hepatocytes were observed among dividing cells at all time points. Notably, HDAg-positive cells appeared in clusters, indicating that HDV was transmitted to daughter cells during liver regeneration even in the absence of de novo infection.

CONCLUSION

This study demonstrates that HDV persists during liver regeneration by transmitting HDV RNA to dividing cells even in the absence of HBV coinfection. The strong persistence capacities of HDV may also explain why HDV clearance is difficult to achieve in HBV/HDV chronically infected patients.

Viral dominance patterns in chronic hepatitis delta determine early response to interferon alpha therapy

Chronic hepatitis D is caused by coinfection of hepatitis B and hepatitis D virus. While HDV is the dominant virus over HBV in the majority of cases, mechanisms and consequences of viral dominance are largely unknown. We aimed to investigate associations between viral dominance patterns and patients' characteristics and inflammatory features; 109 HDV-infected patients treated with PEG-IFNa-2α within the international multicentre, prospective HIDIT-2 trial were studied. Patients were classified as D- or B-dominant if the viral load of one virus exceeded that of the other virus by more than 1log₁₀ . Otherwise, no viral dominance (ND) was described. We used Luminex-based multiplex technology to study 50 soluble immune mediators (SIM) in pretreatment samples of 105 HDV RNA-positive patients. Dominance of HDV was evident in the majority (75%) of cases. While only 7% displayed B-dominance, 17% showed nondominance. D-dominance was associated with downregulation of 4 interleukins (IL-2ra, IL-13, IL-16 and IL-18) and 5 chemokines/cytokines (CTACK (CCL27), MCP-1 (CCL2), M-CSF, TRAIL and ICAM-1) while no analyte was increased. In addition, D-dominance could be linked to a delayed HDV RNA response to pegylated interferon as patients with B-dominance or nondominance showed higher early HDV RNA responses (61% at week 12) than D-dominant patients (11%; P < .001). In conclusion, this study revealed unexpected effects of viral dominance on clinical and immunological features in chronic hepatitis delta patients. Individualizing PEG-IFNa-2α treatment duration should consider viral dominance. Overall, our findings suggest an activated but exhausted IFN system in D-dominant patients.

Anti-HDV seroprevalance among patients with previous HBV infection

OBJECTIVE:

This prospective study aimed to determine the prevalence of anti-HDV seropositivity among subjects who had previous hepatitis B virus (HBV) infection.

METHODS:

Subjects who were admitted to the gastroenterology inpatient clinic of our hospital between August 2016 and July 2017 were screened for previous HBV infection. The subjects who had HBV serology compatible with resolved HBV infection were recruited in the study, and the seroprevalance of anti-HDV was studied. Participants answered a short questionnaire regarding their family history of chronic hepatitis B (CHB) and chronic hepatitis D (CHD) infection and risk factors for transmission. Subjects who were anti-HDV positive were recalled for a control visit, and HBV-DNA and HDV-RNA were assayed in the blood samples of the responders.

RESULTS:

Among 554 subjects who had previous HBV infection, 53 (9.6%) were anti-HDV positive. The mean age was 63.1±15.4 years in the anti-HDV-positive group and 65.9±15.6 years in the anti-HDV-negative group (p=0.19). The most common risk factor for both groups was dental procedures (89% vs 80%, p=0.33). Anti-Hbc IgG, anti-Hbs, and anti-HBeAg seropositivity did not differ between the anti-HDV-positive and -negative groups (for all, p>0.05). Although HDV-RNA was not detectable in all studied samples, only one subject had detectable HBV-DNA in the anti-HDV-positive group.

CONCLUSION:

This study highlighted the prevalence of anti-HDV among subjects who had resolved HBV infection. Long-term follow-up studies, including after the resolution of both infections, are needed to explore HBV–HDV interactions and the behavioral patterns of these viruses.

Reactivation of hepatitis B after liver transplantation: Current knowledge, molecular mechanisms and implications in management

Chronic hepatitis B (CHB) is a major global health problem affecting an estimated 350 million people with more than 786000 individuals dying annually due to complications, such as cirrhosis, liver failure and hepatocellular carcinoma (HCC). Liver transplantation (LT) is considered gold standard for treatment of hepatitis B virus (HBV)-related liver failure and HCC. However, post-transplant viral reactivation can be detrimental to allograft function, leading to poor survival. Prophylaxis with high-dose hepatitis B immunoglobulin (HBIG) and anti-viral drugs have achieved remarkable progress in LT by suppressing viral replication and improving long-term survival. The combination of lamivudine (LAM) plus HBIG has been for many years the most widely used. However, life-long HBIG use is both cumbersome and costly, whereas long-term use of LAM results in resistant virus. Recently, in an effort to develop HBIG-free protocols, high potency nucleos(t)ide analogues, such as Entecavir or Tenofovir, have been tried either as monotherapy or in combination with low-dose HBIG with excellent results. Current focus is on novel antiviral targets, especially for covalently closed circular DNA (cccDNA), in an effort to eradicate HBV infection instead of viral suppression. However, there are several other molecular mechanisms through which HBV may reactivate and need equal attention. The purpose of this review is to address post-LT HBV reactivation, its risk factors, underlying molecular mechanisms, and recent advancements and future of anti-viral therapy.

Antiviral therapy of hepatitis delta virus infection - progress and challenges towards cure

Hepatitis B-/D-virus co-infection causes the most severe form of viral hepatitis, frequently leading to liver cirrhosis, hepatic decompensation and consecutive liver-related mortality. Treatment options for hepatitis delta are limited. The only recommended therapy is pegylated interferon alpha which leads to virological responses in about 25-30% of patients. However, interferon therapy is associated with frequent side-effects and late HDV RNA relapses have been described during long-term follow even in patients who were HDV RNA negative 24 weeks after the end of therapy. Thus, alternative treatment options are urgently needed. Clinical studies have been performed exploring prenylation inhibitors, viral entry inhibitors and nucleic acid polymers to block particle release. We here summarize the progress and challenges towards cure of HDV infection.

Nucleos(t)ide analog(s) prophylaxis after hepatitis B immunoglobulin withdrawal against hepatitis B and D recurrence after liver transplantation

BACKGROUND/AIMS

Nucleos(t)ide analogs (NAs) have made a hepatitis B immunoglobulin (HBIG)-sparing protocol an attractive approach against hepatitis B virus (HBV) recurrence after liver transplantation (LT). However, this approach is considered controversial in patients transplanted for HBV and hepatitis D (HDV) co-infection.

MATERIAL/METHODS

All patients transplanted for HBV/HDV cirrhosis were evaluated. After LT, each patient received HBIG + NAs and then continued with NAs prophylaxis. All patients were followed up with HBV serum markers and HBV DNA, while anti-HDV/HDV RNA was performed in those with HBV recurrence.

RESULTS

A total of 34 recipients were included (22 men, age: 46.7 ± 16 years). After HBIG discontinuation, NAs were received as monoprophylaxis (lamivudine [LAM]: 2, adefovir [AFV]: 1, entecavir: 9, tenofovir [TDF]: 12) or dual prophylaxis (LAM + AFV [or TDF]: 10 patients). Two (5.8%) of the 34 patients had HBV/HDV recurrence after HBIG withdrawal (median follow-up: 28 [range, 12-58] months). These 2 patients had undetectable HBV DNA at LT. Statistical analysis revealed that those with recurrence had received HBIG for shorter period, compared to those without recurrence (median: 9 vs. 28 months, P = 0.008).

CONCLUSIONS

We showed for the first time, to our knowledge, that maintenance therapy with NAs prophylaxis after HBIG discontinuation was effective against HBV/HDV recurrence, but it seems that a longer period of HBIG administration might be needed before it is withdrawn after LT.

[Specific infections in organ transplantation]

This article is concerned with the important topic of infections associated with organ transplantation and includes a discussion on four subtopics. The first section describes the current options in the prevention and therapy of viral hepatitis in association with liver transplantation. Infections with hepatitis B, C, D (delta) and E are discussed with special emphasis on the interferon-free treatment of hepatitis C with the new antiviral drugs.The second section deals with Pseudomonas aeruginosa (PA) infections following lung transplantation (LuTx), which is one of the most frequently detected pathogens in the airway after LuTx. Patients with cystic fibrosis are particularly affected. This is important because studies have shown a clear correlation between chronic PA infections after LuTx and development of chronic transplant failure. Even if the data are still sparse, recommendations on prevention and therapeutic strategies are given. The theme of the third section is the high importance of viral infections after kidney transplantation. In addition to acquired infections, the transplanted organ as well as the recipient can be the source of the infection. The better the transplanted organ is tolerated under moderate immunosuppression, the less common and severe virus infections are. The focus of this section is on three common pathogens: cytomegalovirus, polyomavirus BK and hepatitis viruses.The final section deals with Aspergillus infections following transplantation of various organs. In this context Aspergillus spp. are one of the most commonly occurring fungal diseases. The epidemiology, risk factors, diagnostics, prophylaxis and therapy of invasive aspergillosis are presented.

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.

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.

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

BACKGROUND & AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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