Molecular epidemiology and clinical characteristics of hepatitis D virus infection in Canada

Research advances in serum chitinase-3-like protein 1 in liver fibrosis

While liver fibrosis remains a serious, progressive, chronic liver disease, and factors causing damage persist, liver fibrosis may develop into cirrhosis and liver cancer. However, short-term liver fibrosis is reversible. Therefore, an early diagnosis of liver fibrosis in the reversible transition phase is important for effective treatment of liver diseases. Chitinase-3-like protein 1 (CHI3L1), an inflammatory response factor that participates in various biological processes and is abundant in liver tissue, holds promise as a potential biomarker for liver diseases. Here, we aimed to review research developments regarding serum CHI3L1 in relation to the pathophysiology and diagnosis of liver fibrosis of various etiologies, providing a reference for the diagnosis, treatment, and prognosis of liver diseases.

An updated assessment of hepatitis delta prevalence among adults in Canada: A meta-analysis

Foreign-born (FB) persons represent a large proportion of adults with chronic hepatitis B (CHB) in Canada due to higher prevalence rates in countries of birth for FB persons. Suboptimal awareness and low rates of hepatitis delta virus (HDV) testing contribute to underdiagnosis and gaps in accurate estimates of Canada HDV prevalence. We aim to provide an assessment of CHB and HDV prevalence in Canada using a comprehensive literature review and meta-analysis. A comprehensive literature review of articles reporting HBsAg seroprevalence and anti-HDV prevalence was conducted to calculate country-specific rates and pooled prevalence of CHB and HDV using meta-analyses. Country-specific CHB and HDV rate estimates were combined with number of FB persons in Canada in 2021 from Statistics Canada to estimate total numbers of FB with CHB and HDV, respectively. These estimates were combined with estimates of Canada-born persons with CHB and HDV to yield the total number of persons with CHB and HDV. In 2021, we estimated 0.550 million (M) (95% CI 0.488-0.615) persons with CHB; 0.344 M (95% CI 0.288-0.401) were FB and 0.206 M (95% CI: 0.200-0.214) were Canada-born. The weighted average HDV prevalence among FB persons in Canada was 5.19% (17,848 [95% CI 9611-26,052] persons), among whom 50% emigrated from Asia and 31% from Africa. When combined with estimates of Canada-born persons with HDV, we estimate 35,059 (95% CI: 18,744-52,083) persons with HDV in Canada. In conclusion, we estimate 0.550 M and 35,059 persons living with CHB and HDV, respectively, in Canada in 2021.

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.

Hepatitis B virus genotype surveillance in Canadian blood donors and a referred patient population, 2016-2021

BACKGROUND AND OBJECTIVES

Hepatitis B virus (HBV) genotypes (A-H) have a distinct geographic distribution and are highly associated with the country of birth. Canada has experienced increased immigration over the past decade, primarily from regions where HBV is endemic. This study investigated the proportions and trends of HBV genotypes within blood donor and clinical populations of Canada over the period 2016-2021.

MATERIALS AND METHODS

Study samples involved two cohorts: (1) Canadian blood donors (n = 246) deferred from donation due to HBV test positivity and (2) chronic HBV patients from across Canada (clinically referred population, n = 3539). Plasma or serum was extracted, and the surface antigen and/or polymerase-coding region was amplified and sequenced to determine genotype by phylogenetic analysis.

RESULTS

Six (A-E, G) and eight (A-H) HBV genotypes were detected among deferred blood donors and the clinically referred population, respectively. Differences in HBV genotype proportions between the two cohorts were observed across Canada. Males comprised most of the referred population among genotypes A-E (p < 0.0001), except for genotypes B and C. The median age was younger among blood donors (36 years [range 17-72]) compared with the referred population (41 years [range 0-99]). Distinct trends of increasing (E, referred; B, blood donor) and decreasing genotype prevalence were observed over the study period.

CONCLUSION

HBV genotypes in Canada are highly diverse, suggesting a large immigrant population. Observed trends in genotype prevalence and proportional differences among cohorts imply shifts among the HBV-infected population of Canada, which warrants continued surveillance.

Anti-HDV reflex testing in HBsAg-positive subjects: An efficacious strategy to identify HDV infection

BACKGROUND AND AIMS

The prevalence of HDV infection in HBsAg carriers is about 9.9% in Italy. However, the real prevalence is underestimated because the anti-HDV test is not performed routinely in all HBsAg carriers. The aim of this study was to compare the prevalence and the absolute number of HDV infection identified in HBsAg-positive subjects tested at University Hospital Federico II before and after the introduction of anti-HDV reflex testing.

METHODS

From January to December 2022, reflex test for the detection of total HDV antibodies was performed in all HBsAg-positive subjects tested at University Hospital Federico II. The control group consisted of all the HBsAg-positive subjects tested at the same laboratory in 2019, before the implementation of anti-HDV reflex testing. Sera were evaluated with ADVIA Centaur HBsAgII Qualitative, Liaison Murex HBsAg Quantitative and Liaison Murex Total Anti-HDV Qualitative.

RESULTS

Before reflex testing, anti-HDV had been tested in 16.4% (84/512) of HBsAg-positive subjects, while after its implementation, 100% (484/484) of HBsAg-positive patients was tested for anti-HDV. The anti-HDV positive prevalence was lower than before the introduction of reflex test (10.7% vs. 16.6%) but the absolute number of anti-HDV positive patients increased (14 vs. 52 subjects). HDV-RNA was detectable in 26 (53%) of 49 tested subjects.

CONCLUSIONS

Our data showed that the implementation of anti-HDV reflex testing increased the diagnoses of HDV infection. In this setting, due to the approval of specific anti-HDV drugs, a reflex test for anti-HDV should be implemented to early identify patients with HBV/HDV infection.

Prevalence and determinants of hepatitis delta virus infection among HIV/hepatitis B-coinfected adults in care in the United States

Hepatitis delta virus (HDV) infection increases the risk of liver complications compared to hepatitis B virus (HBV) alone, particularly among persons with human immunodeficiency virus (HIV). However, no studies have evaluated the prevalence or determinants of HDV infection among people with HIV/HBV in the US. We performed a cross-sectional study among adults with HIV/HBV coinfection receiving care at eight sites within the Center for AIDS Research Network of Integrated Clinical Systems (CNICS) between 1996 and 2019. Among patients with available serum/plasma specimens, we selected the first specimen on or after their initial HBV qualifying test. All samples were tested for HDV IgG antibody and HDV RNA. Multivariable log-binomial generalized linear models were used to estimate prevalence ratios (PRs) with 95% CIs of HDV IgG antibody-positivity associated with determinants of interest (age, injection drug use [IDU], high-risk sexual behaviour). Among 597 adults with HIV/HBV coinfection in CNICS and available serum/plasma samples (median age, 43 years; 89.9% male; 52.8% Black; 42.4% White), 24/597 (4.0%; 95% CI, 2.4%-5.6%) were HDV IgG antibody-positive, and 10/596 (1.7%; 95% CI, 0.6%-2.7%) had detectable HDV RNA. In multivariable analysis, IDU was associated with exposure to HDV infection (adjusted PR = 2.50; 95% CI, 1.09-5.74). In conclusion, among a sample of adults with HIV/HBV coinfection in care in the US, 4.0% were HDV IgG antibody-positive, among whom 41.7% had detectable HDV RNA. History of IDU was associated with exposure to HDV infection. These findings emphasize the importance of HDV testing among persons with HIV/HBV coinfection, especially those with a history of IDU.

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.

HDV RNA assays: Performance characteristics, clinical utility, and challenges

Coinfection with HBV and HDV results in hepatitis D, the most severe form of chronic viral hepatitis, frequently leading to liver decompensation and HCC. Pegylated interferon alpha, the only treatment option for chronic hepatitis D for many years, has limited efficacy. New treatments are in advanced clinical development, with one recent approval. Diagnosis and antiviral treatment response monitoring are based on detection and quantification of HDV RNA. However, the development of reliable HDV RNA assays is challenged by viral heterogeneity (at least 8 different genotypes and several subgenotypes), intrahost viral diversity, rapid viral evolution, and distinct secondary structure features of HDV RNA. Different RNA extraction methodologies, primer/probe design for nucleic acid tests, lack of automation, and overall dearth of standardization across testing laboratories contribute to substantial variability in performance characteristics of research-based and commercial HDV RNA assays. A World Health Organization (WHO) standard for HDV RNA, available for about 10 years, has been used by many laboratories to determine the limit of detection of their assays and facilitates comparisons of RNA levels across study centers. Here we review challenges for robust pan genotype HDV RNA quantification, discuss particular clinical needs and the importance of reliable HDV RNA quantification in the context of drug development and patient monitoring. We summarize distinct technical features and performance characteristics of available HDV RNA assays. Finally, we provide considerations for the use of HDV RNA assays in the context of drug development and patient monitoring.

Hepatitis Delta Infection: A Clinical Review

First discovered over 40 years ago, the hepatitis delta virus (HDV) is a unique RNA virus, requiring hepatitis B virus (HBV) antigens for its assembly, replication, and transmission. HBV and HDV can be acquired at the same time (coinfection) or HDV infection can occur in persons with chronic HBV (superinfection). Screening guidelines for HDV are inconsistent. While some guidelines recommend universal screening for all people with HBV, others recommend risk-based screening. Estimates of the global HDV prevalence range from 4.5 to 14.6% among persons with HBV; thus, there may be up to 72 million individuals with HDV worldwide. HDV is the most severe form of viral hepatitis. Compared to HBV monoinfection, HDV coinfection increases the risk of cirrhosis, hepatocellular carcinoma, hepatic decompensation, mortality, and necessity for liver transplant. Despite the severity of HDV, there are few treatment options. Pegylated interferon (off-label use) has long been the only available treatment, although bulevirtide is conditionally approved in some European countries. There are many potential treatments in development, but as yet, there are few effective and safe therapies for HDV infection. In conclusion, given the severity of HDV disease and the paucity of treatments, there is a great unmet need for HDV therapies.

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.