The medical impact of hepatitis D virus infection in Uzbekistan

The distinct spatiotemporal evolutionary landscape of HBV and HDV largely determines the unique epidemic features of HDV globally

Chronic infection of hepatitis B virus (HBV) and hepatitis D virus (HDV) causes the most severe form of viral hepatitis. Due to the dependence on HBV, HDV was deemed to co-evolve and co-migrate with HBV. However, we previously found that the naturally occurred HDV/HBV combinations do not always reflect the most efficient virological adaptation (Wang et al., 2021). Moreover, regions with heavy HBV burden do not always correlate with high HDV prevalence (e.g., East Asia), and vice versa (e.g., Central Asia). Herein, we systematically elucidated the spatiotemporal evolutionary landscape of HDV to understand the unique epidemic features of HDV. We found that the MRCA of HDV was from South America around the late 13th century, was globally dispersed mainly via Central Asia, and evolved into eight genotypes from the 19th to 20th century. In contrast, the MRCA of HBV was from Europe ∼23.7 thousand years ago (Kya), globally dispersed mainly via Africa and East Asia, and evolved into eight genotypes ∼1100 years ago. When HDV stepped in, all present-day HBV genotypes had already formed and its global genotypic distribution had stayed stable geographically. Nevertheless, regionalized HDV adapted to local HBV genotypes and human lineages, contributing to the global geographical separation of HDV genotypes. Additionally, a sharp increase in HDV infections was observed after the 20th century. In conclusion, HDV exhibited a distinct spatiotemporal distribution path compared with HBV. This unique evolutionary relationship largely fostered the unique epidemic features we observe nowadays. Moreover, HDV infections may continue to ramp up globally, thus more efforts are urgently needed to combat this disease.

What Is the Real Epidemiology of Hepatitis D Virus and Why so Many Mixed Messages?

The disease burden of HDV is poorly understood. Our review identified multiple reasons: (1) HDV infection rates are overestimated in the general population due to limited sample sizes, sampling high-risk populations, and significant regional variations, (2) estimates are based on chronic HBV populations, but HBV burden itself is uncertain, (3) there is a lack of testing in at-risk populations, (4) prevalence testing is based on HDV antibody testing and not HDV RNA, which distinguishes between active infection versus prior exposure, (5) older studies used less reliable testing and (6) HBV vaccination programs have affected HDV prevalence, but is often not accounted for.

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.

Elimination of HDV: Epidemiologic implications and public health perspectives

Hepatitis delta virus (HDV) infection causes the severest form of viral hepatitis in humans. Discovered in 1977, it was considered an infection prevalent in the eastern Mediterranean region. Today it is recognized as a global infection of public health importance, however accurate prevalence remains uncertain because of lack of good epidemiological studies. Under-screening for HDV is the single most important factor in under-estimating the true burden of infection. Urgent efforts are therefore needed to apply reliable screening tools and robust surveillance methodologies to study HDV. There is now a move by major hepatology societies to recommend HDV antibody testing in all persons with HBV infection. Important differences also need to be recognized between countries considered endemic or non-endemic countries. While the endemic infections likely spread horizontally in the general population, and is quite often nosocomial, in non-endemic countries special populations may carry the greater burden, such as persons with injection drug use and various sexual exposures. Even in endemic countries, HDV often exists in significant pockets of the general population. HDV has been categorized as an orphan infection due to lack of approved therapies. Recently there have significant advances in therapy and further clinical trials continue. However, as new therapies are approved, equitable access to the medications will become a major public health issue, particularly because most HDV patients live in low or low middle income countries.

Viral hepatitis elimination challenges in low- and middle-income countries-Uzbekistan Hepatitis Elimination Program (UHEP)

BACKGROUND & AIMS

Chronic infection with hepatitis B and C viruses (HBV & HCV) is a major contributor to liver disease and liver-related mortality in Uzbekistan. There is a need to demonstrate the feasibility of large-scale simplified testing and treatment to implement a national viral hepatitis elimination program.

METHODS

Thirteen polyclinics were utilized to screen, conduct follow-up biochemical measures and treat chronic HBV and HCV infection in the general adult population. Task shifting and motivational interviewing training allowed nurses to provide rapid screening and general practitioners (GPs) to treat individuals on-site. An electronic medical system tracked individuals through the cascade of care.

RESULTS

The use of rapid tests allowed for screening of 60 769 people for HCV and HBV over 6 months and permitted outdoor testing during the COVID-19 pandemic along with COVID testing. 13%-14% of individuals were lost to follow-up after the rapid test, and another 62%-66% failed to come in for their consultation. One stop testing and treatment did not result in a statistically increase in retention and lack of patient awareness of viral hepatitis was identified as a key factor. Despite training, there were large differences between GPs and patients initiating treatment.

CONCLUSIONS

The current study demonstrated the feasibility of large-scale general population screening and task shifting in low- and middle-income countries. However, such programs need to be proceeded by awareness campaign to minimize loss to follow up. In addition, multiple trainings are needed for GPs to bolster their skills to talk to patients about treatment.

Silent HDV epidemics culminates in high levels of liver cirrhosis in endemic region despite 20 years of HBV vaccination

The hepatitis delta virus (HDV) is believed to be a vanishing infection in countries with successful hepatitis B virus (HBV) vaccination programs. We assessed the current status of HDV infection in Tuva, a region of the Russia that has been highly endemic for HBV. The proportion of HDV-infected patients among HBsAg-positive patients in the regional registry in 2020 was 32.7% (786/2401). An analysis of the medical records of 514 HDV patients demonstrated that 37.5% (193/514) had liver cirrhosis at the first doctor's visit, and 7.4% of patients lived in families where another family member had HDV. All HDV patients were infected with genotype HDV-1, 94.5% had HBV genotype D, and 5.5% had genotype A. A serosurvey conducted among 1170 healthy volunteers showed that the average detection rate of HBsAg with anti-HDV was 1.0% (95% CI: 0.57-1.81%). No anti-HDV positive samples were detected in participants aged under 30 years. The HBsAg/anti-HDV positivity rate peaked at 7.4% in patients aged 50-59 years, which was significantly higher than in a similar age cohort surveyed in 2008 (1.6%, p < .0001). A Bayesian analysis showed that HDV circulation in Tuva resulted from two waves of introduction, the first in the 1810s (95% HPD: 1741-1834) from Central Asia, and the second in the 1960s (95% HPD: 1953-1979) from Russia. HBV has a much longer history of circulation in Tuva with the MRCA for the predominant genotype HBV-D dated to 972 (95% HPD: 535-1253) for subtype D1, 1274 (95% HPD: 936-1384) for D2, and 1173 (95% HPD: 1005-1618) for D3. A SkyGrid reconstruction of population dynamics showed an increase in the intensity of HDV spread in recent decades. This situation shows the need for HDV screening and prevention measures among people living with HBV.

Epidemiology, presentation, and therapeutic approaches for hepatitis D infections

INTRODUCTION

Chronic Hepatitis D virus (HDV) infection remains an important global public health problem, with a changing epidemiological landscape over the past decade along with widespread implementation of hepatitis B vaccination and human migration. The landscape of HDV treatments has been changing, with therapies that have been under development for the last decade now in late stage clinical trials. The anticipated availability of these new therapies will hopefully replace the current therapies which are minimally effective.

AREAS COVERED

This narrative review discusses the clinical course, screening and diagnosis, transmission risk factors, epidemiology, current and investigational therapies, and liver transplantation in HDV. Literature review was performed using PubMed and ClinicalTrials.gov and includes relevant articles from 1977 to 2022.

EXPERT OPINION

HDV infection is an important global public health issue with a true prevalence that is still unknown. The distribution of HDV infection has changed globally with the availability of HBV vaccination and patterns of human migration. As HDV infection is associated with accelerated disease courses and poor outcomes, the global community needs to agree upon a uniform HDV screening strategy to understand the truth of global prevalence such that new therapies can target appropriate individuals as they become available in the future.

A Review of HDV Infection

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

Hepatitis D virus (HDV) prevalence in Austria is low but causes considerable morbidity due to fast progression to cirrhosis

BACKGROUND

Hepatitis D virus (HDV) coinfection aggravates the course of hepatitis B virus (HBV). The prevalence of HDV in Austria is unknown.

OBJECTIVE

This national study aimed at (i) recording the prevalence of HDV-infection in Austria and (ii) characterizing the "active" HDV cohort in Austria.

METHODS

A total of 10 hepatitis treatment centers in Austria participated in this multicenter study and retrospectively collected their HDV patients between Q1/2010 and Q4/2020. Positive anti-HDV and/or HDV-RNA-polymerase chain reaction (PCR) results were retrieved from local database queries. Disease severity was assessed by individual chart review. Viremic HDV patients with clinical visits in/after Q1/2019 were considered as the "active" HDV cohort.

RESULTS

A total of 347 anti-HDV positive patients were identified. In 202 (58.2%) patients, HDV-RNA-PCR test was performed, and 126/202 (62.4%) had confirmed viremia. Hepatocellular carcinoma was diagnosed in 7 (5.6%) patients, 7 (5.6%) patients underwent liver transplantation, and 11 (8.7%) patients died during follow-up. The "active" Austrian HDV cohort included 74 (58.7%) patients: Evidence for advanced chronic liver disease (ACLD, i.e., histological F3/F4 fibrosis, liver stiffness ≥10 kPa, varices, or hepatic venous pressure gradient ≥6 mmHg) was detected in 38 (51.4%) patients, including 2 (5.3%) with decompensation (ascites/hepatic encephalopathy). About 37 (50.0%) patients of the "active" HDV cohort had previously received interferon treatment. Treatment with the sodium-taurocholate cotransporting polypeptide inhibitor bulevirtide was initiated in 20 (27.0%) patients.

CONCLUSION

The number of confirmed HDV viremic cases in Austria is low (<1% of HBV patients) but potentially underestimated. Testing all HBV patients will increase the diagnostic yield. More than half of viremic HDV patients had ACLD. Improved HDV testing and workup strategies will facilitate access to novel antiviral therapies.

HDV Seroprevalence in HBsAg-Positive Patients in China Occurs in Hotspots and Is Not Associated with HCV Mono-Infection

HDV infection causes severe liver disease, the global health burden of which may be underestimated due to limited epidemiological data. HDV depends on HBV for infection, but recent studies indicated that dissemination can also be supported by other helper viruses such as HCV. We used a rapid point-of-care test and an ELISA to retrospectively test for antibodies against the Hepatitis Delta antigen (anti-HDV-Ab) in 4103 HBsAg-positive and 1661 HBsAg-negative, anti-HCV-positive sera from China and Germany. We found that the HDV seroprevalence in HBsAg-positive patients in China is limited to geographic hotspots (Inner Mongolia: 35/251, 13.9%; Xinjiang: 7/180, 3.9%) and high-risk intravenous drug users (HBV mono-infected: 23/247, 9.3%; HBV-HCV co-infected: 34/107, 31.8%), while none of the 2634 HBsAg carriers from other metropolitan regions were anti-HDV-Ab-positive. In Germany, we recorded an HDV seroprevalence of 5.3% in a university hospital environment. In a cohort of HBsAg-negative, anti-HCV-positive patients that were not exposed to HBV before (anti-HBc-negative), HDV was not associated with HCV mono-infection (Chinese high-risk cohort: 0/365, 0.0%; German mixed cohort: 0/263, 0.0%). However, 21/1033 (2.0%) high-risk HCV patients in China with markers of a previously cleared HBV infection (anti-HBc-positive) were positive for anti-HDV-Ab, with two of them being positive for both HDV and HCV RNA but negative for HBV DNA. The absence of anti-HDV-Ab in HCV mono-infected patients shows that HCV cannot promote HDV transmission in humans.

Assembly and infection efficacy of hepatitis B virus surface protein exchanges in 8 hepatitis D virus genotype isolates

BACKGROUND & AIMS

Chronic HDV infections cause the most severe form of viral hepatitis. HDV requires HBV envelope proteins for hepatocyte entry, particle assembly and release. Eight HDV and 8 HBV genotypes have been identified. However, there are limited data on the replication competence of different genotypes and the effect that different HBV envelopes have on virion assembly and infectivity.

METHODS

We subcloned complementary DNAs (cDNAs) of all HDV and HBV genotypes and systematically studied HDV replication, assembly and infectivity using northern blot, western blot, reverse-transcription quantitative PCR, and in-cell ELISA.

RESULTS

The 8 HDV cDNA clones initiated HDV replication with noticeable differences regarding replication efficacy. The 8 HBV-HBsAg-encoding constructs all supported secretion of subviral particles, however variations in envelope protein stoichiometry and secretion efficacy were observed. Co-transfection of all HDV/HBV combinations supported particle assembly, however, the respective pseudo-typed HDVs differed with respect to assembly kinetics. The most productive combinations did not correlate with the natural geographic distribution, arguing against an evolutionary adaptation of HDV ribonucleoprotein complexes to HBV envelopes. All HDVs elicited robust and comparable innate immune responses. HBV envelope-dependent differences in the activity of the EMA-approved entry inhibitor bulevirtide were observed, however efficient inhibition could be achieved at therapeutically applied doses. Lonafarnib also showed pan-genotypic activity.

CONCLUSIONS

HDVs from different genotypes replicate with variable efficacies. Variations in HDV genomes and HBV envelope proteins are both major determinants of HDV egress and entry efficacy, and consequently assembly inhibition by lonafarnib or entry inhibition by bulevirtide. These differences possibly influence HDV pathogenicity, immune responses and the efficacy of novel drug regimens.

LAY SUMMARY

HDV requires the envelope protein of HBV for assembly and to infect human cells. We investigated the ability of different HDV genotypes to infect cells and replicate. We also assessed the effect that envelope proteins from different HBV genotypes had on HDV infectivity and replication. Herein, we confirmed that genotypic differences in HDV and HBV envelope proteins are major determinants of HDV assembly, de novo cell entry and consequently the efficacy of novel antivirals.

The changing context of hepatitis D

The global epidemiology of hepatitis D is changing with the widespread implementation of vaccination against hepatitis B. In high-income countries that achieved optimal control of HBV, the epidemiology of hepatitis D is dual, consisting of an ageing cohort of domestic patients with advanced liver fibrosis who represent the end stage of the natural history of HDV, and of a younger generation of immigrants from endemic countries who account for the majority of new infections. As observed in Europe in the 1980s, the distinctive clinical characteristic of chronic hepatitis D in endemic countries is the accelerated progression to cirrhosis and hepatocellular carcinoma. Despite some recent progress, the therapeutic management of HDV remains unsatisfactory, as most patients are not cured of HDV with currently available medicines. This review article describes the current epidemiology and clinical features of chronic hepatitis D, based on the literature published in the last 10 years.

The medical impact of hepatitis D virus infection in Asia and Africa; time for a reappraisal

Although hepatitis D is believed to be an important medical problem in Africa and many areas of Asia, the geographical distribution and prevalence rates of infection with the hepatitis D virus (HDV) vary considerably, are often inconsistent and sometimes conflicting. Discrepancies may depend on methodological problems, primarily on different modalities of patients' recruitment; these are analysed in this mini-review, in order to provide a uniform clinical approach when testing patients with chronic HDV disease.

New epidemiology of hepatitis delta

Hepatitis D virus (HDV) is a defective pathogen that needs hepatitis B virus (HBV) for infection. Co-infection of HBsAg-positive individuals with HDV is commonly associated with a more rapid progression to cirrhosis, a higher incidence of hepatocellular carcinoma (HCC) and increased mortality. Initial studies have shown that about 5% of chronic HBV carriers worldwide (15-20 millions) were also infected with HDV. However, recent studies suggest that the prevalence of HDV is at least two- to three-fold higher than previous estimations. Improved diagnostic techniques have shown that HDV infection remains endemic in certain areas of the world. Injection drug users, individuals with high-risk sexual behaviour and patients co-infected with human immunodeficiency virus (HIV) represent the major reservoir of the disease in the Western world. Although the burden of HDV infection significantly decreased in Europe in the nineties, there has been no further decrease in the last decade, probably because of migration from HDV endemic countries. Until new and more effective therapies are available, public health measures should be reinforced by increasing prophylactic HBV vaccination programs, preventing transmission of the virus among parenteral drug users and implementing universal HDV screening of all HBV-infected individuals.