Hepatitis D viremia following orthotopic liver transplantation involves a typical HDV virion with a hepatitis B surface antigen envelope

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.

Successful clinical and virological outcomes of liver transplantation for HDV/HBV-related disease after long-term discontinuation of hepatitis B immunoglobulins

BACKGROUND

Indefinite, long-term administration of hepatitis B immunoglobulins (HBIg), together with a third generation nucleos(t)ide analog (NA), is the currently recommended prophylactic strategy to prevent viral recurrence after liver transplantation (LT) for Hepatitis Delta virus (HDV)/Hepatitis B virus (HBV)-related disease.

METHODS

We retrospectively analyzed the safety and long-term clinical and virological outcomes of a consecutive cohort of 16 patients (10 males, median age 64.5, range 41-75) transplanted for HDV/HBV-related cirrhosis at our Institution, who discontinued HBIg after a median of 24.5 months (range 15-116) after transplant. All patients continued prophylaxis with same NA used before LT. Recurrence of HDV/HBV infection was defined as reappearance of serum HDV-RNA with detectable serum HBsAg and/or HBV-DNA.

RESULTS

The median follow-up after LT was 138 months (range 73-316) and 110 months (range 52-200) after HBIg withdrawal. All patients were HBsAg-positive, HBV-DNA negative, and anti-HDV positive at the time of LT and without coinfections with HCV or HIV. Patients were followed with biochemical and virological tests every 3-6 months after HBIg withdrawal. No recurrences of HDV/HBV infection or disease were observed during monoprophylaxis with NA. In addition, eight patients (50%) spontaneously developed anti-HBs titers above 10 IU/L at a median of 74 months (range 58-140) following HBIG discontinuation.

CONCLUSIONS

HBIg withdrawal after LT is a safe and efficacious strategy in patients transplanted for HDV/HBV disease and is frequently associated with the spontaneous development of serological immunity against HBV. These data call for a revision of current prophylactic recommendations in this setting.

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.

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.

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.

Hepatitis B Immunoglobulin discontinuation in long-term liver transplant patients

BACKGROUND

Hepatitis B immunoglobulin (HBIG)-as a monotherapy or combined with nucleos(t)ide analogs (NUCs)-has effectively lowered Hepatitis B virus (HBV) reinfection after liver transplantation. However, it is associated with high costs and viral resistance. HBIG-free prophylaxis with novel NUCs (tenofovir, entecavir) composes a viable alternative. We evaluated reinfection rate, histological changes, and outcome associated with HBIG discontinuation.

METHODS

A retrospective analysis was performed of patients undergoing liver transplantation due to HBV-induced liver disease at our center since 1988. A controlled HBIG discontinuation was conducted between 2015 and 2017 in 65 patients. Recurrent infection was determined by HbsAg values. Fibrosis and inflammation were evaluated by routine biopsy. The survival of patients after HBIG discontinuation was compared to a control population on HBIG for prophylaxis.

RESULTS

From 1988 to 2013, 352 patients underwent liver transplantation due to HBV-induced liver disease. 169 patients could be included for analysis. 104 (51.5%) patients continued a prophylaxis containing HBIG. HBIG was discontinued in 65 (38.5%) patients in a controlled manner, maintaining an oral NUC. None of those patients showed HBV reinfection or graft dysfunction. No significant changes of inflammation grades (P = .067) or fibrosis stages (P = .051) were detected. The survival of patients after HBIG discontinuation was comparable to the control (P = .95).

CONCLUSION

HBIG withdrawal under continuation of oral NUC therapy is safe and not related to graft dysfunction, based on blood tests and histology. HBIG-free prophylaxis is not associated with a worse outcome and displays a financial relief as well as a logistic simplification during long-term follow-up.

Snake Deltavirus Utilizes Envelope Proteins of Different Viruses To Generate Infectious Particles

Satellite viruses, most commonly found in plants, rely on helper viruses to complete their replication cycle. The only known example of a human satellite virus is the hepatitis D virus (HDV), and it is generally thought to require hepatitis B virus (HBV) to form infectious particles. Until 2018, HDV was the sole representative of the genus Deltavirus and was thought to have evolved in humans, the only known HDV host. The subsequent identification of HDV-like agents in birds, snakes, fish, amphibians, and invertebrates indicated that the evolutionary history of deltaviruses is likely much longer than previously hypothesized. Interestingly, none of the HDV-like agents were found in coinfection with an HBV-like agent, suggesting that these viruses use different helper virus(es). Here we show, using snake deltavirus (SDeV), that HBV and hepadnaviruses represent only one example of helper viruses for deltaviruses. We cloned the SDeV genome into a mammalian expression plasmid, and by transfection could initiate SDeV replication in cultured snake and mammalian cell lines. By superinfecting persistently SDeV-infected cells with reptarenaviruses and hartmaniviruses, or by transfecting their surface proteins, we could induce production of infectious SDeV particles. Our findings indicate that deltaviruses can likely use a multitude of helper viruses or even viral glycoproteins to form infectious particles. This suggests that persistent infections, such as those caused by arenaviruses and orthohantaviruses used in this study, and recurrent infections would be beneficial for the spread of deltaviruses. It seems plausible that further human or animal disease associations with deltavirus infections will be identified in the future.IMPORTANCE Deltaviruses need a coinfecting enveloped virus to produce infectious particles necessary for transmission to a new host. Hepatitis D virus (HDV), the only known deltavirus until 2018, has been found only in humans, and its coinfection with hepatitis B virus (HBV) is linked with fulminant hepatitis. The recent discovery of deltaviruses without a coinfecting HBV-like agent in several different taxa suggested that deltaviruses could employ coinfection by other enveloped viruses to complete their life cycle. In this report, we show that snake deltavirus (SDeV) efficiently utilizes coinfecting reptarena- and hartmaniviruses to form infectious particles. Furthermore, we demonstrate that cells expressing the envelope proteins of arenaviruses and orthohantaviruses produce infectious SDeV particles. As the envelope proteins are responsible for binding and infecting new host cells, our findings indicate that deltaviruses are likely not restricted in their tissue tropism, implying that they could be linked to animal or human diseases other than hepatitis.

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.

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.

Rapid expression and purification of the hepatitis delta virus antigen using the methylotropic yeast Pichia pastoris

OBJECTIVE

Patients with dual hepatitis B (HBV) and hepatitis D (HDV) virus infection are at an increased risk of progression to liver cirrhosis and hepatocellular carcinoma than patients with a single viral infection. Treatment of viral hepatitis due to dual HBV/HDV infection represents a challenge. Currently there is no vaccine against HDV. Recombinant production of HDV antigen (HDAg) is the first step towards a potential vaccine candidate and the development of assays for HDV detection.

RESULTS

This study demonstrates the expression of one HDAg isoform, S-HDAg, in Pichia pastoris. A recombinant vector carrying a tagged gene encoding S-HDAg under the control of the methanol-inducible promoter AOX1 was designed and integrated into P. pastoris X33. The protein, which was purified using a Ni²⁺ affinity column and eluted at 100-150 mM imidazole, has potential as a recombinant antigen for further study.

Hepatitis B Virus and Hepatitis D Virus Recurrence in Patients Undergoing Liver Transplantation for Hepatitis B Virus and Hepatitis B Virus Plus Hepatitis D Virus

BACKGROUND

In this study, we retrospectively analyzed the recurrence of hepatitis B virus (HBV) and hepatitis D virus (HDV) infection after liver transplantation for HBV and HBV+HDV co-infection.

METHODS

Data from patients infected with HBV and HBV+HDV who underwent liver transplantation between March 2003 and June 2013 at the Liver Transplantation Institute of Inonu University were analyzed retrospectively. A total of 255 patients were included in the study. Group 1 (n = 127) comprised patients who underwent liver transplantation because of HBV, and group 2 (n = 128) comprised patients who underwent liver transplantation because of HBV+HDV. A positive HDV antibody serologic test result was taken to indicate liver disease caused by HBV+HDV.

RESULTS

Thirteen of 255 were positive for the HBs Ag (5.1%). Nine (7.1%) and 4 (3.1%) patients were positive for the HBs Ag in groups 1 and 2, respectively (7.1%); the difference was not significant (P = .150). No HDV recurrence was detected in either group. The average time to HBs Ag seroconversion in 13 patients was 7.8 months after surgery (6.34 months in group 1 and 11.1 months in group 2).

CONCLUSIONS

In our study, recurrence rate of HBV after liver transplantation is not statistically different than the recurrence rate of HBV+HDV co-infection. A low recurrence rate was achieved by the prophylaxis protocol in use at our center. There is no standard protocol for prevention of HBV and HDV recurrence; therefore, we need new studies.

Adefovir Dipivoxyl for the Treatment of Delta-Related Liver Cirrhosis

Objective:

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

Case Summary:

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

Discussion:

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

Conclusions:

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

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.

Identification of a natural intergenotypic recombinant hepatitis delta virus genotype 1 and 2 in Vietnamese HBsAg-positive patients

Hepatitis D virus (HDV) infection is acquired as a co- /superinfection of Hepatitis B virus (HBV) and can modulate the pathophysiology of chronic hepatitis B and related liver diseases including hepatocellular carcinoma. Among the eight distinct HDV genotypes reported, relatively few studies have attempted to investigate the prevalence of HDV mixed genotypes and RNA recombination of HDV. With a recorded prevalence of 10-20% HBV infection in Vietnam, this study investigated the HDV variability, HDV genotypes and HDV recombination among twenty-one HDV isolates in Vietnamese HBsAg-positive patients. HDV subgenomic and full-length genome sequences were obtained using newly established HDV-specific RT-PCR techniques. The nucleotide homology was observed from 74.6% to 99.4% among the investigated full-length genome of the HDV isolates. We observed HDV genotype 1 and HDV genotype 2 in the investigated Vietnamese patients. Although no HDV genotype mixtures were observed, we report here a newly identified recombinant of HDV genotypes (HDV 1 and HDV 2). The identified recombinant HDV isolate C03 revealed sequence homology to both HDV genotype 1 (nt1 to nt907) and HDV genotype 2 (nt908 to nt1675; HDAg coding region) with a breakpoint at nt908. Our findings demonstrate the prevalence of intergenotypic recombination between HDV genotypes 1 and 2 in a Vietnamese HBsAg-positive patient. Extended investigation on the distribution and prevalence of HDV, HDV mixed genotypes and recombinant HDV genotypes in a larger Vietnamese population offers vital insights into understanding of the micro-epidemiology of HDV and subsequent pathophysiology in chronic HBV- /HDV-related liver diseases.

Hepatitis D virus coinfection and superinfection

HDV is a defective RNA pathogen requiring the simultaneous presence of HBV to complete its life cycle. Two major specific patterns of infection have been described: the coinfection with HDV and HBV of a susceptible, anti-HBs-negative individual, or the HDV superinfection of a chronic HBV carrier. Coinfection mostly leads to the eradication of both agents, whereas the majority of patients with HDV superinfection evolve to chronic HDV infection and hepatitis. Chronic HDV infection worsens the preexisting HBV-related liver damage. HDV-associated chronic liver disease (chronic hepatitis D) is characterized by necroinflammation and the relentless deposition of collagen culminating, within a few decades, into the development of cirrhosis and hepatocellular carcinoma.

Persistent hepatitis D virus mono-infection in humanized mice is efficiently converted by hepatitis B virus to a productive co-infection

BACKGROUND & AIMS

Clinical studies have shown that hepatitis delta virus (HDV) infection can persist for years and intrahepatic latency of the large delta antigen (HDAg) has been detected following liver transplantation. However, large HDAg arising via RNA-editing is associated with increasing amounts of non-infectious HDV quasi-species. This study investigated whether HDV could persist intrahepatically in the absence of HBV in vivo and whether infectious HDV could subsequently be released following HBV super-infection.

METHODS

Humanized mice were infected with HDV particles lacking HBV. To test for rescue of latent HDV infection 3 and 6 weeks HDV mono-infected mice were super-infected with HBV. Viral loads and cell toxicity were determined by qRT-PCR and immunohistochemistry.

RESULTS

The presence of HDAg-positive human hepatocytes determined after 2, 3, and 6 weeks of HDV inoculation demonstrated establishment and maintenance of intrahepatic HDV mono-infection. Although intrahepatic amounts of large HDAg and edited HDV RNA forms increased over time in HDV mono-infected livers, HBV super-infection led to prompt viremia development (up to 10(8) HDV RNA and 10(7) HBV-DNA copies/ml) even after 6 weeks of latent mono-infection. Concurrently, the number of HDAg-positive human hepatocytes increased, demonstrating intrahepatic HDV spreading. The infectivity of the rescued HDV virions was verified by serial passage in naive chimeric mice.

CONCLUSIONS

HDV mono-infection can persist intrahepatically for at least 6 weeks before being rescued by HBV. Conversion of a latent HDV infection to a productive HBV/HDV co-infection may contribute to HDV persistence even in patients with low HBV replication and in the setting of liver transplantation.

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

BACKGROUND & AIMS

Chronic HDV infection is an inflammatory liver disease and liver transplantation (LTX) remains the only curative treatment option for most patients. The hepatitis D virus (HDV) uses HBsAg as its surface protein, however, it is controversial to what extend HDV may be detected independently of HBsAg in blood and liver after LTX. The aims of this study were to investigate kinetics of HDV RNA and HBsAg early after LTX, to apply the data to a mathematical model and to study long-term persistence of HDV after LTX.

METHODS

We retrospectively analyzed 26 patients with chronic hepatitis delta who underwent LTX between 1994 and 2009. Blood samples were obtained every 1-3 days during the first 14 days after LTX. Data were applied to a mathematical model to study viral kinetics. Available liver biopsy samples were stained for HBV and HDV viral antigens and tested for HBV DNA/cccDNA.

RESULTS

HBsAg and HDV RNA became negative after a median of 5 days (range 1-13) and 4 days (range 1-10), respectively. Early HDV RNA and HBsAg decline paralleled almost exactly in all patients; however the mathematical model showed a high variability of virion death. HDAg stained positive in transplanted livers in six patients in the absence of liver HBV DNA/cccDNA, serum-HBsAg, and HDV RNA for up to 19 months after LTX.

CONCLUSIONS

HDV RNA and HBsAg decline follow almost identical kinetic patterns within the first days after LTX. Nevertheless, intrahepatic latency of HDAg has to be considered when exploring novel concepts to withdraw HBIG.

Hepatitis delta virus

Hepatitis delta virus (HDV) is a small, defective RNA virus that can infect only individuals who have hepatitis B virus (HBV); worldwide more than 15 million people are co-infected. There are eight reported genotypes of HDV with unexplained variations in their geographical distribution and pathogenicity. The hepatitis D virion is composed of a coat of HBV envelope proteins surrounding the nucleocapsid, which consists of a single-stranded, circular RNA genome complexed with delta antigen, the viral protein. HDV is clinically important because although it suppresses HBV replication, it causes severe liver disease with rapid progression to cirrhosis and hepatic decompensation. The range of clinical presentation is wide, varying from mild disease to fulminant liver failure. The prevalence of HDV is declining in some endemic areas but increasing in northern and central Europe because of immigration. Treatment of HDV is with pegylated interferon alfa; however, response rates are poor. Increased understanding of the molecular virology of HDV will identify novel therapeutic targets for this most severe form of chronic viral hepatitis.

Hepatitis D virus: an update

Hepatitis D virus (HDV) infection involves a distinct subgroup of individuals simultaneously infected with the hepatitis B virus (HBV) and characterized by an often severe chronic liver disease. HDV is a defective RNA agent needing the presence of HBV for its life cycle. HDV is present worldwide, but the distribution pattern is not uniform. Different strains are classified into eight genotypes represented in specific regions and associated with peculiar disease outcome. Two major specific patterns of infection can occur, i.e. co-infection with HDV and HBV or HDV superinfection of a chronic HBV carrier. Co-infection often leads to eradication of both agents, whereas superinfection mostly evolves to HDV chronicity. HDV-associated chronic liver disease (chronic hepatitis D) is characterized by necro-inflammation and relentless deposition of fibrosis, which may, over decades, result in the development of cirrhosis. HDV has a single-stranded, circular RNA genome. The virion is composed of an envelope, provided by the helper HBV and surrounding the RNA genome and the HDV antigen (HDAg). Replication occurs in the hepatocyte nucleus using cellular polymerases and via a rolling circle process, during which the RNA genome is copied into a full-length, complementary RNA. HDV infection can be diagnosed by the presence of antibodies directed against HDAg (anti-HD) and HDV RNA in serum. Treatment involves the administration of pegylated interferon-α and is effective in only about 20% of patients. Liver transplantation is indicated in case of liver failure.

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

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

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

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

Histologic findings in recurrent HBV

1. The histopathologic presentation of hepatitis B (HB) infection in liver allografts is generally similar to that seen in the nonallografts. 2. An atypical pattern of recurrent HB, i.e., fibrosing cholestatic hepatitis (FCH) occurs in a small number of patients. These patients present with a severe cholestatic syndrome, which may clinically resemble acute or chronic rejection. 3. There are several other possible causes of acute and chronic hepatitis in liver allografts that may need to be considered. 4. Hepatitis B virus (HBV) infection in the liver allograft can easily be confirmed by performing immunohistochemical stains for hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg). The expression pattern of these HBV antigens varies and is sometimes helpful in determining whether the liver injury is mainly from the HBV or from other causes in coexistence with the HBV infection. 5. Histological grading of the necroinflammatory activity and staging of the fibrosis should only be applied when the changes are related to the recurrent HB. 6. The pathology of liver transplantation is complex; therefore, clinical correlations remain extremely important in arriving at the final and correct diagnosis.

The Woodchuck Model of HDV Infection

The Eastern woodchuck, Marmota monax, has been a useful model system for the study of the natural history of hepadnavirus infection and for the development and preclinical testing of antiviral therapies. The model has also been used for hepatitis delta virus (HDV). In this chapter several new applications of the woodchuck model of HDV infection are presented and discussed. The development of a woodchuck HDV inoculum derived from a molecular clone has facilitated the analysis of viral genetic changes occurring during acute and chronic infection. This analysis has provided insights into one of the more important aspects of the natural history of HDV infection-whether a superinfection becomes chronic. These results could renew interest in further vaccine development. An effective therapy for chronic HDV infection remains an important clinical goal for this agent, particularly because of the severity of the disease and the inability of current hepadnaviral therapies to ameliorate it. The recent application of the woodchuck model of chronic HDV infection to therapeutic development has yielded promising results which indicate that targeting the hepadnavirus surface protein may be a successful therapeutic strategy for HDV.

Pegylated interferon alpha-2b as monotherapy or in combination with ribavirin in chronic hepatitis delta

Therapy of chronic hepatitis delta with standard interferon therapy has met with limited efficacy. This study was designed to examine the efficacy and safety of peginterferon with or without ribavirin. Thirty-eight serum hepatitis B surface antigen- and HDV RNA-positive patients with alanine aminotransferase (ALT) more than 1.5 times the upper normal limit received peginterferon alpha-2b (1.5 microg/kg) alone as monotherapy (n=16) or in combination with ribavirin (n=22), for 48 weeks. Thereafter, all the patients were maintained on peginterferon for 24 weeks and followed for 24 weeks off therapy. The primary end point studied was the virological and biochemical response at the end of follow-up. HDV RNA was determined by single or nested polymerase chain reaction assays. Twenty-seven patients (71%), 11 receiving monotherapy and 16 receiving the combination treatment, completed the follow-up. At the end of treatment, a virological response was observed in 3 of the patients treated with peginterferon (19%) and in 2 of the patients treated with combination therapy (9%), and a biochemical response was observed in 6 (37.5%) and 9 patients (41%), respectively. In nonresponders, ALT diminished from a mean of 174+/-53 to 86+/-41 IU/L. At the end of follow-up, serum HDV RNA was negative in 8 patients (21%), and a biochemical response was detected in 10 patients (26%). Treatment was discontinued in 25% of the patients, and dosing was modified in 58%. In conclusion, a prolonged course of peginterferon alpha-2b resulted in clearance of serum HDV RNA and ALT normalization in a fifth of patients with chronic hepatitis D, while ribavirin had no effect on the viral clearance rate. Overall tolerance of therapy was poor.

Genetic changes in hepatitis delta virus from acutely and chronically infected woodchucks

A woodchuck-derived hepatitis delta virus (HDV) inoculum was created by transfection of a genotype I HDV cDNA clone directly into the liver of a woodchuck that was chronically infected with woodchuck hepatitis virus. All woodchucks receiving this inoculum became positive for HDV RNA in serum, and 67% became chronically infected, similar to the rate of chronic HDV infection in humans. Analysis of HDV sequences obtained at 73 weeks postinfection indicated that changes had occurred at a rate of 0.5% per year; many of these modifications were consistent with editing by host RNA adenosine deaminase. The appearance of sequence changes, which were not evenly distributed on the genome, was correlated with the course of HDV infection. A limited number of modifications occurred in the consensus sequence of the viral genome that altered the sequence of the hepatitis delta antigen (HDAg). All chronically infected animals examined exhibited these changes 73 weeks following infection, but at earlier times, only one of the HDV carriers exhibited consensus sequence substitutions. On the other hand, sequence modifications in animals that eventually recovered from HDV infection were apparent after 27 weeks. The data are consistent with a model in which HDV sequence changes are selected by host immune responses. Chronic HDV infection in woodchucks may result from a delayed and weak immune response that is limited to a small number of epitopes on HDAg.

Clevudine inhibits hepatitis delta virus viremia: a pilot study of chronically infected woodchucks

In a small controlled study, clevudine, a potent inhibitor of hepadnaviruses, including hepatitis B virus and woodchuck hepatitis virus, suppressed hepatitis delta virus (HDV) viremia in chronically infected woodchucks. Suppression was correlated with the marked reduction of woodchuck hepatitis virus surface antigen in individual animals, consistent with the concept that repression of surface antigen expression may be a useful antiviral strategy for HDV.

Lamivudine therapy in chronic delta hepatitis: a multicentre randomized-controlled pilot study

BACKGROUND

Delta virus (HDV)-related chronic hepatitis is difficult to treat.

AIMS

To evaluate the efficacy of lamivudine 100 mg daily on serum HDV-RNA, hepatitis D virus antibodies and alanine aminotransferase levels, liver histology, and on hepatitis B surface antigen seroconversion.

METHODS

Thirty-one hepatitis B surface antigen-positive, HDV-RNA-positive patients with ALT > or = 1.5 upper normal level and compensated liver disease were randomized (1:2 ratio) to placebo (group A, n = 11) or lamivudine (group B, n = 20) for 52 weeks; thereafter, all patients were given lamivudine for 52 weeks and followed up for 16 weeks.

RESULTS

Twenty-five patients (81%) completed the study. No patient was HDV-RNA-negative at week 52; three patients (11%) were negative at week 104. Two of them remained HDV-RNA-negative at week 120, and one lost the hepatitis B surface antigen without seroconversion. Paired pre-treatment and week 104 liver biopsies were available from 19 patients: of which three of seven (43%) from group A and two of 12 patients (17%) from group B had a > or =2 point decrease in the Ishak necroinflammatory score.

CONCLUSION

A sustained complete response was achieved in 8% of hepatitis D virus-infected patients treated with lamivudine and a partial histological response in 26% of them. Hepatitis D virus viraemia was unaffected, even in patients when hepatitis B virus replication was lowered by lamivudine therapy.

Transplantation of hepatitis B surface antigen-positive livers into hepatitis B virus-positive recipients and the role of hepatitis delta coinfection

The scarcity of liver donors requires consideration of grafts from sources not previously used. Allografts from hepatitis B surface antigen (HBsAg)-carriers without a significant liver disease have been proposed for liver transplant recipients with hepatitis B virus (HBV)-related cirrhosis and hepatocellular carcinoma (HCC). Combination prophylaxis schemes against HBV post-liver transplantation (LT) recurrence are currently available; the efficacy of those schemes in HBV-related cirrhosis and HCC must be assessed. This report describes the allocation of HBsAg-positive grafts in three HBsAg-positive recipients, with HBV-related cirrhosis and evolving HCC lesions, two of them with hepatitis Delta virus (HDV) coinfection. Patients were administered anti-hepatitis B immunoglobulins (HBIGs) and lamivudine in order to prevent HBV recurrence. In spite of anti-HBV prophylaxis, HBV infection did persist after LT in all patients (no serum clearance of HBsAg). HBV replication assessed by serum HBV deoxyribonucleic acid (DNA) presence was detected in the first month after LT in the 3 recipients. A prompt HDV reinfection with a clinical and histological pattern of hepatitis was observed in the 2 HBV / HDV coinfected recipients. In 1 of them, an evolving chronic hepatitis required a second LT. The non-HDV-infected patient showed an uneventful follow-up, but the lack of the neutralizing effect of HBIGs and the high risk of escape mutants forced the addition of adefovir-dipivoxil to lamivudine, in order to prevent viral variants and hepatitis recurrence. In conclusion, allografts from HBsAg-positive donors in HBsAg-positive recipients are associated with the persistence of the HBsAg after LT due to the failure of HBIG prophylaxis, even if lamivudine does inhibit virion production. This condition favors HDV replication and HDV hepatitis recurrence in coinfected patients. The allocation of HBsAg-positive grafts in HBsAg-positive recipients could be justified only in recipients without HDV coinfection and a combined prophylaxis with lamivudine and adefovir-dipivoxil is currently the best way to manage escape mutants in these recipients.

Transcriptional activation of the promoter of human cytomegalovirus immediate early gene (CMV-IE) by the hepatitis B viral X protein (HBx) through the NF-kappaB site

The reactivation of latent cytomegalovirus (CMV) in a human by another viral infection may induce virus-related symptoms. Based on this presumption, we investigated the effect of HBx on the activation of the CMV-IE, which is also known as a transactivator and potential oncogene. The HBx transactivated the CMV-IE promoter by up to 4- and 18-fold factors in human liver HepG2 and lung fibroblast MRC-5 cells, respectively. Cotransfection of HBx with each transcription factor presented in the CMV-IE promoter showed that only NF-kappaB synergistically activated the promoter by up to a 14-fold factor. Serial deletion assays and point mutation analysis showed that the third NF-kappaB site (nt -267 to -258) and the second one (nt -162 to -153) appeared as the major responsible site and minor one, respectively, for the transactivation. These results suggest the possibility that the HBV infection of a cell previously infected by CMV would exert influence on the reactivation of the latent cytomegalovirus in a human to induce virus-related symptoms.

[Hepatitis D]

The hepatitis D virus (HDV), also called delta virus, is a small circular RNA virus. The HDV is dependent on the hepatitis B virus (HBV) and can cause infection in normal individuals with hepatitis B or yet, superinfect chronic HBV carriers. Three genotypes have already been cloned and sequenced. Infection with HDV has a worldwide distribution and a high HDV endemicity has been documented in the western Amazon region, in Brazil. It has been estimated that 18 million people are infected with this virus amongst the 350 million carriers of the HBV around the world. The HDV transmission and risk factors for infection are similar to those for HBV infection. The diagnosis is based on the immunohistological identification of HDAg in the liver and detection of IgM and IgG anti-HD in serum using RIA or EIA. The clinical course of hepatitis D is variable. Fulminant disease occurs more commonly in hepatitis B and D than in other forms of acute viral hepatitis. Chronic HDV infection is usually associated with severe histological changes in the liver and with a rapidly progressive course, that can lead to cirrhosis, liver failure and death. Treatment of chronic hepatitis D is currently unsatisfactory and interferon alpha is the only agent found to have some effect on the course of chronic hepatitis. Orthotopic liver transplantation is indicated for terminal cases of cirrhosis. Prophylaxis for HDV infection is possible by vaccination against the hepatitis B virus.

Clearance of hepatitis B surface antigen in chronic carriers of hepatitis delta antibodies

BACKGROUND/AIMS

We evaluated the rate of seroclearance of the hepatitis B surface antigen (HBsAg) and its clinical significance in patients with chronic hepatitis delta virus (HDV).

METHODS

Antibody to HDV was tested in HBsAg-positive subjects admitted to our Hospital from 1991 to 1995. In 1997, a biochemical and virologic study was performed in the surviving anti-HD-positive patients who had not undergone transplantation. As a control, a cohort of 106 HBsAg-positive, anti-HD-negative patients was studied.

RESULTS

One hundred and forty-one subjects were originally positive for anti-HD. After 4 years of follow-up, six of the 60 patients who underwent re-evaluation (10%) had cleared the HBsAg: three of the six patients had minimal changes at the initial liver histology and normal ALT, whereas in the remaining three patients with chronic active hepatitis ALT normalized during the observation. Anti-HD persisted in five of the six patients. Only one patient had raised anti-HBs. In contrast, three of 106 HBsAg carriers without HDV infection (2.8%) cleared the HBsAg within the same time and seroconverted to anti-HBs (p=0.002).

CONCLUSION

HBsAg clearance is increased over the years in HDV patients compared to ordinary HBsAg carriers, and is often associated with improvement of HDV disease without seroconversion to anti-HBs.

Animal models of hepatitis delta virus infection and disease

Hepatitis delta virus (HDV) is a defective RNA virus with similarities to unusual subviral pathogens of higher plants. It requires hepatitis B virus (HBV) for its replication/transmission, and HBV-infected humans are the only established host. HDV causes both severe acute hepatitis and rapidly progressive chronic disease in some individuals. The HDV life cycle involves remarkable features, such as ribozyme- mediated autocatalytic processes, Pol II-directed RNA synthesis from a single-stranded circular RNA template, and RNA editing. Much of our understanding of the nature of this pathogen derives from experimental studies in the chimpanzee model of HBV infection. The hepadnavirus-infected eastern woodchuck also is capable of supporting HDV replication and offers opportunities for the development of control strategies that might be applicable to human type D hepatitis.

Viral hepatitis in the liver transplant recipient

Understanding and management of HBV and HCV infection in the OLT recipient has evolved rapidly in the last decade. The spontaneous risk for viral recurrence after transplantation is high, but has been decreased effectively in hepatitis B-positive recipients with the use of HBIG and lamivudine. HCV recurrence as defined by histologic injury is almost universal, although graft or patient outcomes for the first 8 years after OLT do not appear to be limited by HCV serostatus. However, effective prophylactic regimens that alter the natural history of HCV reinfection do not currently exist, and with longer follow-up into the second decade, the prevalence of HCV-related graft failure is likely to increase.

Hepatitis delta virus: the molecular basis of laboratory diagnosis

Infection with hepatitis delta virus (HDV), a satellite virus of hepatitis B virus (HBV), is associated with severe and sometimes fulminant hepatitis. The traditional methods for the diagnosis of HDV infection, such as detection of serum anti-HD antibodies, are sufficient for the clinical diagnosis of delta infection. However, such techniques lack the sensitivity and specificity required to more accurately characterize the nature of HDV infection and to assess the efficacy of therapies. Recent improvements in molecular techniques, such as HDV RNA hybridization and RT-PCR, have provided increased diagnostic precision and a more thorough understanding of the natural course of HDV infection. These advances have enhanced the clinician's ability to accurately evaluate the stage of HDV infection, response to therapy, and occurrence of reinfection after orthotopic liver transplant. This review focuses on the recent advances in the understanding of the molecular biology of HDV and in the laboratory diagnosis of HDV infection.

The synergistic transactivation of the hepatitis B viral (HBV) pregenomic promoter by the E6 protein of human papillomavirus type 16 (HPV-16 E6) with HBV X protein was mediated through the AP1 site of E element in the enhancer I (EnI) in human liver cell

Infection by HBV of a cell already infected with other viral species or vice versa has been suggested as being involved in hepatocellular carcinoma. Using the CAT assay method, we investigated the interactive roles of HBx and potentially oncogenic and transactivating viral early proteins such as Ad5 E1A, HPV-16 E6, and SV40 T ag. In the presence of HBx, only HPV-16 E6 showed significant synergistic transactivation of EnI. We further investigated the function of the HPV-16 E6 using deletion, heterologous promoter, and mutation analyses on the EnI promoter. The results showed that the synergistic effect was mediated through the AP1 site of the E element in EnI by the direct activation of AP1 and support the idea that the infection by HBV of the cell with other viral species such as HPV-16 could increase the transcription activity of the HBV and other oncogenes containing an AP1 site in the promoter.