Global Perspective on Hepatitis B Virus Infections in the Era of Effective Vaccines

Prevalence of hepatitis B infection in the Gambian population: A narrative review of recent developments

Hepatitis B is a "silent epidemic", fifty to a hundred (50-100) times more infectious than HIV, a potentially life-threatening liver infection caused by the hepatitis B virus (HBV). HBV can cause acute and chronic infection and subsequently results in a high risk of death from cirrhosis and liver cancer. Despite the availability of a safe and effective vaccine, HBV continues to be a global burden including in The Gambia. This study reviewed the recent trends in the epidemiological characteristics of HBV in the Gambia. The researchers conducted an online literature search for primary studies on HBV prevalence published in the past two decades from Jan 1992 to Feb 2022 inclusive on Google Scholar, PubMed, and Scopus. All retrieved studies were assessed for eligibility according to specific inclusion/exclusion criteria, data completeness, and methodological coherence. We found that HBV infection prevalence is above 8% in The Gambia. Moreover, HBV is the most common cause of hepatocellular carcinoma (HCC) in Gambia. Liver cirrhosis and HCC have the highest mortality contribution among hepatitis patients, with occult HBV carriers as major culprits. Also, vaccination coverage has declined from 91% to 88% according to reports from current literature. To achieve the WHO goal of eliminating HBV by 2030, policies targeting infection transmission control among risk groups, community awareness programs, research, price reduction of drugs, mass vaccinations, and diagnostics should be urgently instituted.

Hepatitis B Virus Immunity Gap: A Six-Year Laboratory Data Review of Hepatitis B Serological Profiles in Gauteng Province, South Africa

Background

In 1995, the hepatitis B vaccine in South Africa was incorporated into the childhood expanded programme of immunization. We report on immunity gaps of laboratory-based hepatitis B virus (HBV) among patients in public facilities in Gauteng Province from 1st January 2014 to 31st December 2019. Methodology. We analyzed HBV serological data extracted from the National Health Laboratory Services Central Data Warehouse (NHLS CDW). A descriptive analysis was performed for hepatitis B surface antigen (HBsAg), antibodies to HBV core (anti-HBc) total, anti-HBc IgM, and antibodies to HBV surface antigen (anti-HBs) according to annual distribution, age groups, and sex.

Results

The HBsAg positivity rate was 7.0% (75,596/1,095,561; p=0.001): 7.4% (96,532/944,077) in the 25 years and over age group and 4.0% (358/9,268 and 325/10,864) in the under 5 and 13-24 year age groups. The positivity rates of the other HBV serological markers were as follows: anti-HBc total was 37.0% (34,377/93,711; p  <  0.001), anti-HBc IgM was 2.4% (5,661/239,237; p=0.05), and anti-HBs was 37.0% (76,302/206,138; p ≤ 0.001). Naturally acquired HBV immunity was detected in 25.7% (11,188/43,536) of patients in the 25 years and over age group, and 9.7% and 8.2% (113/1,158 and 541/6,522) among those under 5 years and 13-24 year age group, respectively (p  <  0.001). Vaccine-induced immunity was 56.6% (656/1,158) in children under 5 years and 10.2% (4,425/43,536) among those 25 years and above (p  <  0.001). Fifty-six percent (29,404/52,581) of patients were HBV seronegative; predominantly among patients in the 13-24 year age group (60.6%; (3,952/6,522)) and 25 years and over (56.3% (24,524/43,536)) (p=<0.001).

Conclusion

The HBV infection seroprevalence remains high in South Africa, with Gauteng province having high intermediate endemicity. However, the HBV immunity gap has shifted from younger children to older children and adults.

Global Epidemiology and Genetics of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the leading cancers worldwide. Classically, HCC develops in genetically susceptible individuals who are exposed to risk factors, especially in the presence of liver cirrhosis. Significant temporal and geographic variations exist for HCC and its etiologies. Over time, the burden of HCC has shifted from the low-moderate to the high sociodemographic index regions, reflecting the transition from viral to nonviral causes. Geographically, the hepatitis viruses predominate as the causes of HCC in Asia and Africa. Although there are genetic conditions that confer increased risk for HCC, these diagnoses are rarely recognized outside North America and Europe. In this review, we will evaluate the epidemiologic trends and risk factors of HCC, and discuss the genetics of HCC, including monogenic diseases, single-nucleotide polymorphisms, gut microbiome, and somatic mutations.

Chronic Hepatitis B Virus and Hepatitis D Virus: New Developments

Hepatitis B virus (HBV) and hepatitis D virus are leading causes of morbidity and mortality worldwide. Despite the availability of HBV vaccinations that are 98% to 100% effective, an estimated 820,000 annual deaths were attributed to HBV in 2019, mainly related to the sequelae of cirrhosis and hepatocellular carcinoma. Because disease prevalence is concentrated outside of the United States, it is overlooked, but with expanded vaccination recommendations provided by the Centers for Disease Control and Prevention and recommended screening, as well as heightened awareness by health care providers, we can work toward the eradication of this preventable disease.

Genetic associations in chronic hepatitis B infection: toward developing polygenic risk scores

Chronic hepatitis B (CHB) infection results in multiple clinical phenotypes of varying severity. One of the critical gaps in CHB management is the lack of a genetic-based tool to aid existing hepatocellular carcinoma and cirrhosis risk stratification models for patients with active CHB. Such individual predictive models for CHB are plagued by an inherent limitation of discriminatory power that clearly indicates the need for their improvement. In this article, we highlight genetic association studies in CHB that identified HLA and cytokine genetic susceptibility loci to CHB. We advance the position that translating CHB genetic susceptibility loci into polygenic risk scores will be a welcome addendum to the current arsenal of CHB outcome predictive models. We conclude with comments on hurdles that future research efforts should address within the research enclave of CHB and advocate for increased genetic data representation from sub-Saharan Africa.

The negative impact of most relevant infections on fertility and assisted reproduction technology

Infections may act with variable impact on the physiopathology of the reproductive organs, determining infertility or reducing the outcomes of assisted reproduction technology. The aim of this narrative review is to describe the existing evidence regarding the pathogens with a supposed or recognized role in reproductive medicine. Viral hepatitis, as well as HIV, can reduce sperm quality. Syphilis carries a risk of erectile dysfunction and increased endometrial thickness. Chlamydia is the main cause of pelvic inflammatory disease. In relation to Mycoplasma and Ureaplasma spp., only few species seem to show a correlation with infertility and poor in-vitro fertilization outcomes. There is evidence of a role for bacterial vaginosis in early pregnancy loss. HPV infection in males seems to determine infertility. Herpesviruses are more a risk for fetuses than for fertility itself. Zika virus is responsible for altered early embryo development and waiting to conceive is recommended in suspected or confirmed cases. The impact of SARS-CoV-2 is yet to be elucidated. Rubella and toxoplasmosis can provoke important congenital defects and therefore screening is mandatory before conception; a vaccine for Rubella is recommended. Further and well-designed studies are still needed to better elucidate the role of some infectious agents, to improve fertility and its treatments.

Hepatitis B virus polymerase-specific T cell epitopes shift in a mouse model of chronic infection

BACKGROUND

Chronic hepatitis B virus (HBV) infection (CHB) is a significant public health problem that could benefit from treatment with immunomodulators. Here we describe a set of therapeutic HBV vaccines that target the internal viral proteins.

METHODS

Vaccines are delivered by chimpanzee adenovirus vectors (AdC) of serotype 6 (AdC6) and 7 (AdC7) used in prime only or prime-boost regimens. The HBV antigens are fused into an early T cell checkpoint inhibitor, herpes simplex virus (HSV) glycoprotein D (gD), which enhances and broadens vaccine-induced cluster of differentiation (CD8)⁺ T cell responses.

RESULTS

Our results show that the vaccines are immunogenic in mice. They induce potent CD8⁺ T cell responses that recognize multiple epitopes. CD8⁺ T cell responses increase after a boost, although the breadth remains similar. In mice, which carry high sustained loads of HBV particles due to a hepatic infection with an adeno-associated virus (AAV)8 vector expressing the 1.3HBV genome, CD8⁺ T cell responses to the vaccines are attenuated with a marked shift in the CD8⁺ T cells' epitope recognition profile.

CONCLUSIONS

Our data show that in different stains of mice including those that carry a human major histocompatibility complex (MHC) class I antigen HBV vaccines adjuvanted with a checkpoint inhibitor induce potent and broad HBV-specific CD8⁺ T cell responses and lower but still detectable CD4⁺ T cell responses. CD8⁺ T cell responses are reduced and their epitope specificity changes in mice that are chronically exposed to HBV antigens. Implications for the design of therapeutic HBV vaccines are discussed.

Occult Hepatitis B virus (HBV) infection and challenges for hepatitis elimination: A literature review

Occult hepatitis B infection (OBI) is characterized by the detection of hepatitis B virus (HBV) DNA in serum or liver but negativity for hepatitis B surface antigen. OBI, which is thought to be maintained by host, immunological, viral and/or epigenetic factors, is one of the most challenging clinical features in the study of viral hepatitis. Currently, there is no validated detection test for OBI. It is believed that OBI is widely distributed throughout the world, with a higher prevalence in populations at high-risk HBV, but the detailed worldwide prevalence patterns are unknown. We conducted a survey of recently published studies on OBI rates across all continents. High prevalence rates of OBI are observed in some specific groups, including patients with hepatitis C virus, human immunodeficiency virus co-infection or hepatocellular carcinoma. In 2016, the World Health Organization adopted strategies to eliminate viral hepatitis by 2030, but the difficulties in detecting and treating OBI currently challenge this goal. Subjects with OBI can transmit HBV, and episodes of reactivation can occur. Further studies to understanding the mechanisms that drive the development of OBI are needed and can contribute to efforts at eliminating viral hepatitis.

State of the art vaccination strategies as primary prevention to reduce incidence of gastrointestinal cancers

Immunizations have influenced the epidemiology of numerous gastrointestinal cancers. Human papillomavirus (HPV) is a common sexually transmitted infection (STI). Although most infections are transient and asymptomatic, persistent infections with oncogenic strains of HPV can progress to cervical, anal, penile, vaginal, vulvar, and oropharyngeal cancers. The introduction of HPV vaccinations has drastically reduced incidences of HPV-vaccine related infections and HPV related cervical cancers. The vaccine has proven to be safe and effective however, HPV vaccination rates have yet to reach target goals in the U.S. and many countries worldwide have not incorporated the vaccine into national immunization programs. The first successful nationwide vaccination program was employed against hepatitis B virus (HBV) in Taiwan in 1984 and demonstrated a statistically significant decrease in the incidence of hepatocellular carcinoma (HCC) in the 6 to 10 years after implementation of universal HBV vaccinations in infants. Twenty-year follow-up studies have continued to demonstrate statistically significant decreased rates of HBV related HCC among vaccinated populations. Despite the successful decrease in incidence of HBV-related HCC, efforts to create an effective prophylactic vaccination against hepatitis C virus (HCV) to prevent chronic HCV infection and its associated morbidity, including HCV-related HCC, have to date been unsuccessful.

An Updated Assessment of Chronic Hepatitis B Prevalence Among Foreign-Born Persons Living in the United States

BACKGROUND AND AIMS

Although prevalence of chronic hepatitis B (CHB) in the USA includes 0.42 million (range, 0.28-0.67) U.S.-born persons, foreign-born (FB) persons contribute a substantially larger number to the burden of CHB in the USA. Over the past decade, patterns of U.S. immigration have changed and many countries have implemented HBV prevention programs. This study aims to estimate the number of FB persons with CHB in the USA by country of origin, updating our 2011 study.

APPROACH AND RESULTS

We performed systematic searches for articles published in 2009-2019 reporting HBsAg seroprevalence in emigrants and in-country populations of 117 countries. Data meeting inclusion criteria were combined with data from our 2011 study to calculate pooled prevalence estimates for 99 countries using meta-analyses (total 2,800 surveys involving 112 million subjects). Combining country-specific CHB rate estimates with the number of FB in the USA in 2018, by country of origin from the U.S. Census Bureau, we estimate that the number of FB with CHB in the USA in 2018 was 1.47 million (95% CI, 1.21-1.73), substantially higher than previously reported. The weighted average CHB prevalence for all FB in the USA in 2018 was 3.07%. Approximately 59% of FB with CHB in the USA in 2018 emigrated from Asia, 19% from the Americas, and 15% from Africa. Subgroup analyses found that for many countries, CHB rates are higher in males than females and have declined over the past three decades, but no consistent pattern is observed between emigrant and in-country rates.

CONCLUSIONS

Including FB and U.S.-born persons, the total prevalence of CHB in the USA may be as high as 2.4 million.

Detection and Genetic Characterization of Hepatitis B and D Viruses: A Multi-Site Cross-Sectional Study of People Who Use Illicit Drugs in the Amazon Region

Hepatitis B (HBV) and delta (HDV) viruses are endemic in the Amazon region, but vaccine coverage against HBV is still limited. People who use illicit drugs (PWUDs) represent a high-risk group due to common risk behavior and socioeconomic factors that facilitate the acquisition and transmission of pathogens. The present study assessed the presence of HBV and HBV-HDV co-infection, identified viral sub-genotypes, and verified the occurrence of mutations in coding regions for HBsAg and part of the polymerase in HBV-infected PWUDs in municipalities of the Brazilian states of Amapá and Pará, in the Amazon region. In total, 1074 PWUDs provided blood samples and personal data in 30 municipalities of the Brazilian Amazon. HBV and HDV were detected by enzyme-linked immunosorbent assay and polymerase chain reaction. Viral genotypes were identified by nucleotide sequencing followed by phylogenetic analysis, whereas viral mutations were analyzed by specialized software. High rates of serological (32.2%) and molecular (7.2%) markers for HBV were detected, including cases of occult HBV infection (2.5%). Sub-genotypes A1, A2, D4, and F2a were most frequently found. Escape mutations due to vaccine and antiviral resistance were identified. Among PWUDs with HBV DNA, serological (19.5%) and molecular (11.7%) HDV markers were detected, such as HDV genotypes 1 and 3. These are worrying findings, presenting clear implications for urgent prevention and treatment needs for the carriers of these viruses.

Moderate Heat-Assisted Gene Electrotransfer for Cutaneous Delivery of a DNA Vaccine Against Hepatitis B Virus

An estimated 350 million people are living with chronic Hepatitis B virus (HBV) worldwide. Preventative HBV vaccination in infants has reduced the disease burden; however, insufficient immunization programs and access obstacles leave vulnerable populations at risk for infection in endemic regions. Gene electrotransfer (GET) using a noninvasive multielectrode array (MEA) provides an alternative platform for DNA vaccination in the skin. DNA vaccines are nonlive and nonreplicating and temperature stable unlike their counterparts. In addition, their simple engineering allows them to be manufactured quickly at a low cost. In the current work, we present the combination of GET and moderate heating for delivery of a DNA vaccine against HBV. Our laboratory has previously shown the synergy between moderate tissue preheating at 43°C and GET with the MEA as a means to reduce both the applied voltage and pulse number to achieve similar if not higher gene expression than GET alone. In this study, we expand upon this work, by optimizing the plasmid dose to achieve the highest level of expression. Using the reporter gene luciferase, we found that an intradermal injection of 100 μL at 1 mg/mL induced the highest expression levels across all tested GET conditions. We then evaluated our moderate heat-assisted GET platform for the intradermal delivery of a plasmid encoding Hepatitis B surface antigen (pHBsAg) via a prime and prime plus boost vaccination protocol. At 18 weeks, following the prime plus boost protocol, we observed that a high-voltage low-pulse GET condition with moderate heating (45 V 36 p+heat) generated antibodies against Hepatitis B surface antigen (HBsAb) at peak measuring 230-fold over injection of plasmid DNA alone with moderate heating. HBsAbs remained robust over the 30-week observation period. These data suggest that moderate heat-assisted GET has the potential to induce strong immune responses, an attractive feature for development of an alternative vaccine delivery platform.

The Epidemiological Impact of STIs among General and Vulnerable Populations of the Amazon Region of Brazil: 30 years of Surveillance

Sexually transmitted infections (STIs) represent a worldwide public health problem and, although many of them are curable, they continue to be neglected, especially in areas with a low human development index, such as in the northern region of Brazil. This review describes the results of 30 years of studies at the Virus Laboratory at the Federal University of Pará, including the prevalence and molecular epidemiology of HIV-1, HTLV-1/2, HPV, HBV, Treponema pallidum and Chlamydia trachomatis among urban and non-urban populations, and also in vulnerable groups in the Brazilian Amazon. Control strategies and challenges in preventing STIs are discussed considering this immense geographic region, where essential health services are unable to reach the entire population, especially the most vulnerable, such as female sex workers, people who use illicit drugs, remnants of quilombolos and indigenous communities.

Host RNA quality control as a hepatitis B antiviral target

Inhibition of the host RNA polyadenylating polymerases, PAPD5 and PAPD7 (PAPD5/7), with dihydroquinolizinone, a small orally available, molecule, results in a rapid and selective degradation of hepatitis B virus (HBV) RNA, and hence reduction in the amounts of viral gene products. DHQ, is a first in class investigational agent and could represent an entirely new category of HBV antivirals. PAPD5 and PAPD7 are non-canonical, cell specified, polyadenylating polymerases, also called terminal nucleotidyl transferases 4B and 4A (TENT4B/A), respectively. They are involved in the degradation of poor-quality cell transcripts, mostly non-coding RNAs and in the maturation of a sub-set of transcripts. They also appear to play a role in shielding some mRNA from degradation. The results of studies with DHQ, along with other recent findings, provide evidence that repression of the PAPD5/7 arm of the cell "RNA quality control" pathway, causes a profound (multi-fold) reduction rather than increase, in the amount of HBV pre-genomic, pre-core and HBsAg mRNA levels in tissue culture and animal models, as well. In this review we will briefly discuss the need for new HBV therapeutics and provide background about HBV transcription. We also discuss cellular degradation of host transcripts, as it relates to a new family of anti-HBV drugs that interfere with these processes. Finally, since HBV mRNA maturation appears to be selectively sensitive to PAPD5/7 inhibition in hepatocytes, we discuss the possibility of targeting host RNA "quality control" as an antiviral strategy.

Hepatitis B-management of acute infection and active inflammation in pregnancy-a hepatologist's perspective

Women at childbearing age and pregnant ladies living in the areas of high or intermediate prevalence of hepatitis B virus (HBV) remain at risk of getting the infection and passing the infections to their offspring via mother-to-child transmission (MTCT) of HBV. HBV infection may affect the mothers by active hepatitis, very occasionally liver cirrhosis and rarely fulminant hepatitis and liver failure. The virus may be transmitted to the babies despite immunoprophylaxis in the setting of very high maternal viral load. Tenofovir disoproxil fumarate (TDF) has been shown to be efficacious to reduce MTCT of HBV, which contributes to the elimination of chronic HBV infection by 2030, the goal set by World Health Organization.

Engineering Cellular Biosensors with Customizable Antiviral Responses Targeting Hepatitis B Virus

SynNotch receptor technology is a versatile tool that uses the regulatory notch core portion with an extracellular scFv and an intracellular transcription factor that enables to program customized input and output functions in mammalian cells. In this study, we designed a novel synNotch receptor comprising scFv against HBs antigen linked with an intracellular artificial transcription factor and exploited it for viral sensing and cellular immunotherapy. The synNotch receptor expressing cells sensed HBV particles and membrane-bound HBs antigens and responded by expressing reporter molecules, secNL or GFP. We also programmed these cells to dispense antiviral responses such as type I interferon and anti-HBV neutralizing mouse-human chimeric antibodies. Our data reveal that synNotch receptor signaling works for membrane-bound ligands such as enveloped viral particles and proteins borne on liposomal vesicles. This study establishes the concepts of "engineered immunity" where the synNotch platform is utilized for cellular immunotherapy against viral infections.

Effect of Hepatitis Viruses on the Nrf2/Keap1-Signaling Pathway and Its Impact on Viral Replication and Pathogenesis

With respect to their genome and their structure, the human hepatitis B virus (HBV) and hepatitis C virus (HCV) are complete different viruses. However, both viruses can cause an acute and chronic infection of the liver that is associated with liver inflammation (hepatitis). For both viruses chronic infection can lead to fibrosis, cirrhosis and hepatocellular carcinoma (HCC). Reactive oxygen species (ROS) play a central role in a variety of chronic inflammatory diseases. In light of this, this review summarizes the impact of both viruses on ROS-generating and ROS-inactivating mechanisms. The focus is on the effect of both viruses on the transcription factor Nrf2 (nuclear factor erythroid 2 (NF-E2)-related factor 2). By binding to its target sequence, the antioxidant response element (ARE), Nrf2 triggers the expression of a variety of cytoprotective genes including ROS-detoxifying enzymes. The review summarizes the literature about the pathways for the modulation of Nrf2 that are deregulated by HBV and HCV and describes the impact of Nrf2 deregulation on the viral life cycle of the respective viruses and the virus-associated pathogenesis.