Tolerance and immunity to pathogens in early life: insights from HBV infection. Semin Immunopathol. 2017;39:643-652. [PMID: 28685270 PMCID: PMC5711997 DOI: 10.1007/s00281-017-0641-1]

Life-threatening infections in human newborns: Reconciling age-specific vulnerability and interindividual variability

In humans, the interindividual variability of clinical outcome following exposure to a microorganism is immense, ranging from silent infection to life-threatening disease. Age-specific immune responses partially account for the high incidence of infection during the first 28 days of life and the related high mortality at population level. However, the occurrence of life-threatening disease in individual newborns remains unexplained. By contrast, inborn errors of immunity and their immune phenocopies are increasingly being discovered in children and adults with life-threatening viral, bacterial, mycobacterial and fungal infections. There is a need for convergence between the fields of neonatal immunology, with its in-depth population-wide characterization of newborn-specific immune responses, and clinical immunology, with its investigations of infections in patients at the cellular and molecular levels, to facilitate identification of the mechanisms of susceptibility to infection in individual newborns and the design of novel preventive and therapeutic strategies.

Interspecies comparison of the early transcriptomic changes associated with hepatitis B virus exposure in human and macaque immune cell populations

Background and aims

Hepatitis B virus (HBV) infection affects 300 million individuals worldwide, representing a major factor for the development of hepatic complications. Although existing antivirals are effective in suppressing replication, eradication of HBV is not achieved. Therefore, a multi-faceted approach involving antivirals and immunomodulatory agents is required. Non-human primates are widely used in pre-clinical studies due to their close evolutionary relationship to humans. Nonetheless, it is fundamental to identify the differences in immune response between humans and these models. Thus, we performed a transcriptomic characterization and interspecies comparison of the early immune responses to HBV in human and cynomolgus macaques.

Methods

We characterized early transcriptomic changes in human and cynomolgus B cells, T cells, myeloid and plasmacytoid dendritic cells (pDC) exposed to HBV ex vivo for 2 hours. Differentially-expressed genes were further compared to the profiles of HBV-infected patients using publicly-available single-cell data.

Results

HBV induced a wide variety of transcriptional changes in all cell types, with common genes between species representing only a small proportion. In particular, interferon gamma signaling was repressed in human pDCs. At the gene level, interferon gamma inducible protein 16 (IFI16) was upregulated in macaque pDCs, while downregulated in humans. Moreover, IFI16 expression in pDCs from chronic HBV-infected patients anti-paralleled serum HBsAg levels.

Conclusion

Our characterization of early transcriptomic changes induced by HBV in humans and cynomolgus macaques represents a useful resource for the identification of shared and divergent host responses, as well as potential immune targets against HBV.

Unusual serological profile in hepatitis B virus (HBV) infection associated with a probable clinical case of acute exacerbation of pre-existing chronic HBV infection

BACKGROUND

Acute or chronic HBV infection in an individual can be laboratory characterized according to the serological profile of the viral markers in the bloodstream, and the dynamics monitoring of these markers is necessary to assess the disorder course and the infection outcome. However, under certain circumstances unusual or atypical serological profiles may be observed in both acute and chronic HBV infection. They are considered as such because they do not properly characterize the form or infection clinical phase or because they seem inconsistent, considering the viral markers dynamics in both clinical contexts. This manuscript comprises the analysis of an unusual serological profile in HBV infection.

METHODS AND RESULTS

This clinical-laboratory study, had as reference a patient who presented clinical profile suggestive of acute HBV infection after recent exposure, whose laboratory data were initially compatible with this clinical presentation. However, the serological profile analysis and its monitoring demonstrated unusual pattern of viral markers expression, which has been observed in several clinical contexts, and is often associated a number of agent- or host-related factors.

CONCLUSION

The serological profile analyzed here, associated with the biochemical markers serum levels found, is indicative of active chronic infection, consequence of viral reactivation. This finding suggests that in the event of unusual serological profiles in HBV infection, if the influence of agent- or host-related factors is not properly considered and neither the viral markers dynamics properly analyzed, there may be mistake in the infection clinical diagnosis, especially when the patient's clinical and epidemiological history is unknown.

A nomogram based on HBeAg, AST, and age to predict non-minimal liver inflammation in CHB patients with ALT <80 U/L

Objective

Precise assessment of liver inflammation in untreated hepatitis B e antigen (HBeAg)-positive patients with chronic hepatitis B virus (HBV) infection can determine when to initiate antiviral therapy. The aim of this study was to develop and validate a nomogram model for the prediction of non-minimal liver inflammation based on liver pathological injuries combined with age and alanine aminotransferase (ALT), aspartate aminotransferase (AST), hepatitis B surface antigen (HBsAg), HBeAg, and HBV DNA quantification.

Methods

We retrospectively included 735 HBeAg-positive chronic hepatitis B (CHB) patients with ALT < 80 U/L as the primary cohort and prospectively enrolled 196 patients as the validation cohort. Multivariate logistic regression analysis identified independent impact factors. A nomogram to predict significant liver inflammation was developed and validated.

Results

Multivariate logistic regression analysis showed that HBeAg, AST, and age were independent risk factors for predicting non-minimal liver inflammation in untreated CHB patients. The final formula for predicting non-minimal liver inflammation was Logit(P) = -1.99 - 0.68 × Log₁₀HBeAg + 0.04 × Age + 0.06 × AST. A nomogram for the prediction of non-minimal liver inflammation was established based on the results from the multivariate analysis. The predicted probability of the model being consistent with the actual probability was validated by the calibration curves, showing the best agreement in both the primary and validation cohorts. The C-index was 0.767 (95%CI = 0.734-0.802) in the primary cohort and 0.749 (95%CI = 0.681-0.817) in the prospective validation cohort.

Conclusions

The nomogram based on HBeAg, AST, and age might help predict non-minimal liver inflammation in HBeAg-positive CHB patients with ALT < 80 U/L, which is practical and easy to use for clinicians.

Hepatitis B virus X gene impacts on the innate immunity and immune-tolerant phase in chronic hepatitis B virus infection

BACKGROUND AND AIMS

The immunologic features involved in the immune-tolerant phase of chronic hepatitis B (CHB) virus (HBV) infection are unclear. The hepatitis B virus X (HBx) protein disrupts IFN-β induction by downregulating MAVS and may destroy subsequent HBV-specific adaptive immunity. We aimed to analyse the impacts of genetic variability of HBx in CHB patients on the immune-tolerant phase during long-term follow-up.

METHODS

Children with CHB in the immune-tolerant phase were recruited and followed longitudinally. HBx gene sequencing of infecting HBV strains was performed, and the effects of HBx mutations on the immune-tolerant phase were assessed. Restoration of the host immune response to end the immune-tolerant phase was investigated by immunoblotting, immunostaining, ELISA and reporter assays of MAVS/IFN-β signalling in liver cell lines, patient liver tissues and the HBV plasmid replication system.

RESULTS

A total of 173 children (median age, 6.92 years) were recruited. Patients carrying HBx R87G, I127V and R87G + I127V double mutations exhibited higher cumulative incidences of immune-tolerant phase breakthrough (p = .011, p = .006 and p = .017 respectively). Cells transfected with HBx R87G and I127V mutants and pHBV1.3-B6.3 replicons containing the HBx R87G and I127V mutations exhibited statistically increased levels of IFN-β, especially under poly(I:C) stimulation or Flag-MAVS cotransfection. HA-HBx wild-type interacted with Flag-MAVS and enhanced its ubiquitination, but this ability was diminished in the R87G and I127V mutants.

CONCLUSIONS

HBx suppresses IFN-β induction. R87G and I127V mutation restored IFN-β production by preventing MAVS degradation, contributing to curtailing the HBV immune-tolerant phase in CHB patients.

The COVID-19 pandemic in the African continent

In December 2019, a new coronavirus, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and associated disease, coronavirus disease 2019 (COVID-19), was identified in China. This virus spread quickly and in March, 2020, it was declared a pandemic. Scientists predicted the worst scenario to occur in Africa since it was the least developed of the continents in terms of human development index, lagged behind others in achievement of the United Nations sustainable development goals (SDGs), has inadequate resources for provision of social services, and has many fragile states. In addition, there were relatively few research reporting findings on COVID-19 in Africa. On the contrary, the more developed countries reported higher disease incidences and mortality rates. However, for Africa, the earlier predictions and modelling into COVID-19 incidence and mortality did not fit into the reality. Therefore, the main objective of this forum is to bring together infectious diseases and public health experts to give an overview of COVID-19 in Africa and share their thoughts and opinions on why Africa behaved the way it did. Furthermore, the experts highlight what needs to be done to support Africa to consolidate the status quo and overcome the negative effects of COVID-19 so as to accelerate attainment of the SDGs.

Monocytic MDSCs homing to thymus contribute to age-related CD8+ T cell tolerance of HBV

Hepatitis B virus exposure in children usually develops into chronic hepatitis B (CHB). Although hepatitis B surface antigen (HBsAg)–specific CD8⁺ T cells contribute to resolve HBV infection, they are preferentially undetected in CHB patients. Moreover, the mechanism for this rarely detected HBsAg-specific CD8⁺ T cells remains unexplored. We herein found that the frequency of HBsAg-specific CD8⁺ T cells was inversely correlated with expansion of monocytic myeloid-derived suppressor cells (mMDSCs) in young rather than in adult CHB patients, and CCR9 was upregulated by HBsAg on mMDSCs via activation of ERK1/2 and IL-6. Sequentially, the interaction between CCL25 and CCR9 mediated thymic homing of mMDSCs, which caused the cross-presentation, transferring of peripheral HBsAg into the thymic medulla, and then promoted death of HBsAg-specific CD8⁺ thymocytes. In mice, adoptive transfer of mMDSCs selectively obliterated HBsAg-specific CD8⁺ T cells and facilitated persistence of HBV in a CCR9-dependent manner. Taken together, our results uncovered a novel mechanism for establishing specific CD8⁺ tolerance to HBsAg in chronic HBV infection.

Molecular characterization of hepatitis B virus (HBV) isolated from a pediatric case of acute lymphoid leukemia, with a delayed response to antiviral treatment: a case report

BACKGROUND

Tenofovir disoproxil fumarate (TDF) is effectively used as the first-line antiviral for chronic hepatitis B virus (HBV) infection in adults and children older than 12 years. To date, no confirmed case of virologic breakthrough (VBT) in a pediatric case has been reported.

CASE PRESENTATION

Here we describe a case of a 5-year old, asymptomatically infected with HBV infection two months after chemotherapy for precursor B acute lymphoblastic leukemia (ALL). Although the 5-year old male is South African, his family originated from Guinea. At the end of the one-year follow-up, the infection progressed to chronic HBV infection, with a high viral load. At 36 weeks (8 months) post-treatment with lamivudine (LAM), there was a partial virologic response (PVR) and after 61 weeks (14 months), he was switched to TDF rescue monotherapy. Even with TDF treatment, he still experienced VBT and subsequent PVR. The full-length genome of HBV isolated 78 weeks after the switch to rescue TDF monotherapy was sequenced and belonged to genotype E. In addition to the LAM mutations (rtS256G and rtM267L), missense mutations in B-cell, T-cell, HLA class I and II-restricted epitopes emerged, which were to evade and escape host surveillance, leading to delayed viral clearance, persistence and disease progression. Two further events of VBT occurred between weeks 113 and 141 of TDF rescue-therapy. Viral loads and liver enzymes are normalizing progressively with long-term therapy.

CONCLUSION

Although the host immune reconstitution may be delayed, prolonged TDF treatment was effective in treating this pediatric case of HBV infection with VBT and PVR.

Adenovirus vector encoding TPPII ignites HBV-specific CTL response by activating autophagy in CD8+ T cell

Early studies have shown that autophagy and TPPII are associated with HBV infection. In this study, adenovirus vector containing TPPII was constructed to immunize HBV transgenic mice in vivo to explore the potential mechanism of autophagy and HBV infection. Our goal is to provide new ideas for immunotherapy of hepatitis B. First, adenovirus vector containing TPPII was constructed. Then, we used adenovirus to immunize HBV transgenic mice and ATG5 knockout HBV transgenic mice. The autophagy of CD8+ T cells was detected by transmission electron microscopy and immunofluorescence electron microscopy, Western blot was used to detect the expression of autophagy LC3 and BECN1, CTL reaction, HBV DNA and HBsAg in serum, HBsAg and HBcAg in liver tissues by immunohistochemistry, to further examine the possible mechanisms involved in autophagy. Adv-HBcAg-TPPII promotes autophagy of CD8+ T lymphocyte, activates CTL response, inhibits HBV DNA replication and HBsAg expression, and PI3K/ Akt /m TOR signalling pathway may be involved in autophagy. This study demonstrates that autophagy of CD8+ T cells was induced by Adv-HBcAg-TPPII and the molecular mechanism may be related to the PI3K/ Akt /m TOR signalling pathway, providing a possible theoretical basis for immunotherapy of hepatitis B.

Quantitative HBsAg versus HBV DNA in Predicting Significant Hepatitis Activity of HBeAg-Positive Chronic HBV Infection

(1) Background: As specialparameters in predicting significant hepatitis activity of hepatitis B e antigen (HBeAg)-positive chronic hepatitis B virus (HBV) infection, the quantitative standard of HBV DNA has not been agreed and that of hepatitis B surface antigen(HBsAg) has not been formed. Our objective is to evaluate the validity of HBsAg and HBV DNA in predicting the significant hepatitis activity of HBeAg-positive patients. (2) Methods: A population of 516 patients with HBeAg-positive chronic HBV infection was enrolled. Serum ALT was measured using an Abbott Architect c16000 autoanalyzer; diagnoses of liver pathological grade and stage referred to the Scheuer standard. Three levels of significant hepatitis activity were preset, which were successively “ALT ≥ 20 IU/L or Grade > G1 or Stage > S1”, “ALT ≥ 30 IU/L or Grade > G1 or Stage > S1” and “ALT ≥ 40 IU/L or Grade > G1 or Stage > S1”. (3) Results: A subpopulation of 288 patients with possible high HBV replication was selected based on locally weighted scatterplot smoothing regression curves between ALT and HBsAg, HBeAg and HBV DNA. In the subpopulation with possible high HBV replication, areas under receiver operating characteristic curves of HBsAg for predicting the three levels of significant hepatitis activity were successively 0.868, 0.839 and 0.789, which were all significantly greater than those of HBV DNA, as those were successively 0.553, 0.550 and 0.574 (p = 0.0002, p < 0.0001 and p < 0.0001). With the standard of HBsAg ≤ 4.699 log₁₀ IU/mL, the sensitivity and specificity of HBsAg for predicting the three levels of significant hepatitis activity were successively 75.81% and 81.82%, 79.23% and 78.57% and 80.82% and 67.44%. (4) Conclusion: Quantitative HBsAg instead of HBV DNA is valuable in predicting significant hepatitis activity of HBeAg-positive chronic HBV infection.

Explaining the unexpected COVID-19 trends and potential impact across Africa

Official COVID-19 case counts and mortality rates across Africa are lower than had been anticipated. Research reports, however, indicate far higher exposure rates than the official counts in some countries. Particularly in Western and Central Africa, where mortality rates are disproportionately lower than the rest of the continent, this occurrence may be due to immune response adaptations resulting from (1) frequent exposure to certain pro-inflammatory pathogens, and (2) a prevalence of low-grade inflammation coupled with peculiar modifications to the immune response based on one's immunobiography. We suggest that the two factors lead to a situation where post infection, there is a rapid ramp-up of innate immune responses, enough to induce effective defense and protection against plethora pathogens. Alongside current efforts at procuring and distributing vaccines, we draw attention to the need for work towards appreciating the impact of the apparently widespread, asymptomatic SARS-CoV-2 infections on Africa's populations vis a vis systemic inflammation status and long-term consequences for public health.

Explaining the unexpected COVID-19 trends and potential impact across Africa

Official COVID-19 case counts and mortality rates across Africa are lower than had been anticipated. Research reports, however, indicate far higher exposure rates than the official counts in some countries. Particularly in Western and Central Africa, where mortality rates are disproportionately lower than the rest of the continent, this occurrence may be due to immune response adaptations resulting from (1) frequent exposure to certain pro-inflammatory pathogens, and (2) a prevalence of low-grade inflammation coupled with peculiar modifications to the immune response based on one's immunobiography. We suggest that the two factors lead to a situation where post infection, there is a rapid ramp-up of innate immune responses, enough to induce effective defense and protection against plethora pathogens. Alongside current efforts at procuring and distributing vaccines, we draw attention to the need for work towards appreciating the impact of the apparently widespread, asymptomatic SARS-CoV-2 infections on Africa's populations vis a vis systemic inflammation status and long-term consequences for public health.

Effects of intrauterine exposure to hepatitis B virus in foetuses

Foetal response to hepatitis B viral infection is still unknown. The mechanisms of persistent infection that occurs more often in mother-to-child transmission than adult transmission are also unclear. Various aspects of the environmental factors that accelerate or inhibit infection and the cytokine responses are associated with the persistence of infection. Several studies showed that the cytokine poor immune response in immaturity causes the persistence of the infection. However, some reports suggested that a mature immune response was the cause of this persistent infection. This review comprehensively summarized the reports from in vitro, in vivo as well as clinical reports regarding the responses of the foetuses of hepatitis B infected mothers to the micro-organism. The mechanism of more opportunities to be persistently infected via the mother-to-child transmission route is also summarized and discussed. Since there are limited clinical reports at this time, this review will provide evidence for future studies regarding the intrauterine infection mechanism and foetal response to hepatitis B virus to elucidate the mechanisms responsible for mother-to-child transmission. This understanding may lead to effective interventions to control mother-to-child hepatitis B infection in the future.

High infectious disease burden as a basis for the observed high frequency of asymptomatic SARS-CoV-2 infections in sub-Saharan Africa

Following the coronavirus outbreaks described as severe acute respiratory syndrome (SARS) in 2003 and the Middle East respiratory syndrome (MERS) in 2012, the world has again been challenged by yet another corona virus, named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). SARS-CoV-2 infections were first detected in a Chinese Province in December 2019 and then declared a pandemic by the World Health Organization in March 2020. An infection caused by SARS-CoV-2 may result in asymptomatic, uncomplicated or fatal coronavirus disease 2019 (COVID-19). Fatal disease has been linked with the uncontrolled "cytokine storm" manifesting with complications mostly in people with underlying cardiovascular and pulmonary disease conditions. The severity of COVID-19 disease and the associated mortality has been disproportionately lower in terms of number of cases and deaths in Africa and also Asia in comparison to Europe and North America. Also, persons of colour residing in Europe and North America have been identified as a highly susceptible population due to a combination of several socioeconomic factors and poor access to quality healthcare. Interestingly, this has not been the case in sub-Saharan Africa where majority of the population are even more deprived of the aforementioned factors. On the contrary, sub-Saharan Africa has recorded the lowest levels of mortality and morbidity associated with the disease, and an overwhelming proportion of infections are asymptomatic. Whilst it can be argued that these lower number of cases in Africa may be due to challenges associated with the diagnosis of the disease such as lack of trained personnel and infrastructure, the number of persons who get infected and develop symptoms is proportionally lower than those who are asymptomatic, including asymptomatic cases that are never diagnosed. This review discusses the most probable reasons for the significantly fewer cases of severe COVID-19 disease and deaths in sub-Saharan Africa.

Analysis of chronic inflammatory lesions of the colon for BMMF Rep antigen expression and CD68 macrophage interactions

Bovine meat and milk factors (BMMF) are routinely found in bovine sera and dairy products, predominantly of Eurasian dairy cattle. BMMF DNA and proteins are demonstrated in tissues of colon cancer patients, specifically interstitial macrophages of peritumor tissues. BMMF represent plasmid-like, zoonotic infectious agents with an indirect role in cancer formation by inducing chronic inflammation leading to oxidative stress and DNA mutation in nearby replicating cells, which may develop into polyps as progenitors for colon cancer. Detection of BMMF during long latency periods prior to symptoms developing allows for specific preventive and early therapeutic measures. Detection of BMMF might offer a prognostic tool for prediction of patient survival, preventive approaches, and therapy success.

Consumption of Eurasian bovine meat and milk has been associated with cancer development, in particular with colorectal cancer (CRC). In addition, zoonotic infectious agents from bovine products were proposed to cause colon cancer (zur Hausen et al., 2009). Bovine meat and milk factors (BMMF) are small episomal DNA molecules frequently isolated from bovine sera and milk products, and recently, also from colon cancer (de Villiers et al., 2019). BMMF are bioactive in human cells and were proposed to induce chronic inflammation in precancerous tissue leading to increased radical formation: for example, reactive oxygen and reactive nitrogen species and elevated levels of DNA mutations in replicating cells, such as cancer progenitor cells (zur Hausen et al., 2018). Mouse monoclonal antibodies against the replication (Rep) protein of H1MSB.1 (BMMF1) were used to analyze BMMF presence in different cohorts of CRC peritumor and tumor tissues and cancer-free individuals by immunohistochemistry and Western blot. BMMF DNA was isolated by laser microdissection from immunohistochemistry-positive tissue regions. We found BMMF Rep protein present specifically in close vicinity of CD68⁺ macrophages in the interstitial lamina propria adjacent to CRC tissues, suggesting the presence of local chronic inflammation. BMMF1 (modified H1MSB.1) DNA was isolated from the same tissue regions. Rep and CD68⁺ detection increased significantly in peritumor cancer tissues when compared to tissues of cancer-free individuals. This strengthens previous postulations that BMMF function as indirect carcinogens by inducing chronic inflammation and DNA damage in replicating cells, which represent progress to progenitor cells for adenoma (polyps) formation and cancer.

Understanding Antibody Responses in Early Life: Baby Steps towards Developing an Effective Influenza Vaccine

The immune system of young infants is both quantitatively and qualitatively distinct from that of adults, with diminished responsiveness leaving these individuals vulnerable to infection. Because of this, young infants suffer increased morbidity and mortality from respiratory pathogens such as influenza viruses. The impaired generation of robust and persistent antibody responses in these individuals makes overcoming this increased vulnerability through vaccination challenging. Because of this, an effective vaccine against influenza viruses in infants under 6 months is not available. Furthermore, vaccination against influenza viruses is challenging even in adults due to the high antigenic variability across viral strains, allowing immune evasion even after induction of robust immune responses. This has led to substantial interest in understanding how specific antibody responses are formed to variable and conserved components of influenza viruses, as immune responses tend to strongly favor recognition of variable epitopes. Elicitation of broadly protective antibody in young infants, therefore, requires that both the unique characteristics of young infant immunity as well as the antibody immunodominance present among epitopes be effectively addressed. Here, we review our current understanding of the antibody response in newborns and young infants and discuss recent developments in vaccination strategies that can modulate both magnitude and epitope specificity of IAV-specific antibody.

High infectious disease burden as a basis for the observed high frequency of asymptomatic SARS-CoV-2 infections in sub-Saharan Africa

Following the coronavirus outbreaks described as severe acute respiratory syndrome (SARS) in 2003 and the Middle East respiratory syndrome (MERS) in 2012, the world has again been challenged by yet another corona virus, named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). SARS-CoV-2 infections were first detected in a Chinese Province in December 2019 and then declared a pandemic by the World Health Organization in March 2020. An infection caused by SARS-CoV-2 may result in asymptomatic, uncomplicated or fatal coronavirus disease 2019 (COVID-19). Fatal disease has been linked with the uncontrolled "cytokine storm" manifesting with complications mostly in people with underlying cardiovascular and pulmonary disease conditions. The severity of COVID-19 disease and the associated mortality has been disproportionately lower in terms of number of cases and deaths in Africa and also Asia in comparison to Europe and North America. Also, persons of colour residing in Europe and North America have been identified as a highly susceptible population due to a combination of several socioeconomic factors and poor access to quality healthcare. Interestingly, this has not been the case in sub-Saharan Africa where majority of the population are even more deprived of the aforementioned factors. On the contrary, sub-Saharan Africa has recorded the lowest levels of mortality and morbidity associated with the disease, and an overwhelming proportion of infections are asymptomatic. Whilst it can be argued that these lower number of cases in Africa may be due to challenges associated with the diagnosis of the disease such as lack of trained personnel and infrastructure, the number of persons who get infected and develop symptoms is proportionally lower than those who are asymptomatic, including asymptomatic cases that are never diagnosed. This review discusses the most probable reasons for the significantly fewer cases of severe COVID-19 disease and deaths in sub-Saharan Africa.

Successful treatment of infantile hepatitis B with lamivudine: A case report

BACKGROUND

How to treat infantile hepatitis B virus (HBV) infection remains a controversial issue. The nucleoside analogue lamivudine (LAM) has been approved to treat children (2 to 17 years old) with chronic hepatitis B. Here, we aimed to investigate the benefit of LAM treatment in infantile hepatitis B.

CASE SUMMARY

A 4-mo-old infant born to a hepatitis B surface antigen (HBsAg)-positive woman was found to be infected by HBV during a health checkup. Liver chemistry and HBV seromarker tests showed alanine aminotransferase of 106 U/L, HBsAg of 685.2 cut-off index, hepatitis B “e” antigen of 1454.0 cut-off index, and HBV DNA of > 1.0 × 10⁹ IU/mL. LAM treatment (20 mg/d) was initiated, and after 19 mo, serum HBsAg was entirely cleared and hepatitis B surface antibody was present. The patient received LAM treatment for 2 years in total and has been followed for 3 years. During this period, serum hepatitis B surface antibody has been persistently positive, and serum HBV DNA was undetectable.

CONCLUSION

Early treatment of infantile hepatitis B with LAM could be safe and effective.

Animal Models of Hepatitis B Virus Infection-Success, Challenges, and Future Directions

Chronic hepatitis B virus (HBV) infection affects more than 250 million people worldwide, which greatly increases the risk for terminal liver diseases, such as liver cirrhosis and hepatocellular carcinoma (HCC). Even though current approved antiviral therapies, including pegylated type I interferon (IFN) and nucleos(t)ide analogs, can effectively suppress viremia, HBV infection is rarely cured. Since HBV exhibits a narrow species tropism and robustly infects only humans and higher primates, progress in HBV research and preclinical testing of antiviral drugs has been hampered by the scarcity of suitable animal models. Fortunately, a series of surrogate animal models have been developed for the study of HBV. An increased understanding of the barriers towards interspecies transmission has aided in the development of human chimeric mice and has greatly paved the way for HBV research in vivo, and for evaluating potential therapies of chronic hepatitis B. In this review, we summarize the currently available animal models for research of HBV and HBV-related hepadnaviruses, and we discuss challenges and future directions for improvement.

Highly multiplexed 2-dimensional imaging mass cytometry analysis of HBV-infected liver

Studies of human hepatitis B virus (HBV) immune pathogenesis are hampered by limited access to liver tissues and technologies for detailed analyses. Here, utilizing imaging mass cytometry (IMC) to simultaneously detect 30 immune, viral, and structural markers in liver biopsies from patients with hepatitis B e antigen⁺ (HBeAg⁺) chronic hepatitis B, we provide potentially novel comprehensive visualization, quantitation, and phenotypic characterizations of hepatic adaptive and innate immune subsets that correlated with hepatocellular injury, histological fibrosis, and age. We further show marked correlations between adaptive and innate immune cell frequencies and phenotype, highlighting complex immune interactions within the hepatic microenvironment with relevance to HBV pathogenesis.

Checkpoint inhibition through small molecule-induced internalization of programmed death-ligand 1

Programmed death-ligand 1 is a glycoprotein expressed on antigen presenting cells, hepatocytes, and tumors which upon interaction with programmed death-1, results in inhibition of antigen-specific T cell responses. Here, we report a mechanism of inhibiting programmed death-ligand 1 through small molecule-induced dimerization and internalization. This represents a mechanism of checkpoint inhibition, which differentiates from anti-programmed death-ligand 1 antibodies which function through molecular disruption of the programmed death 1 interaction. Testing of programmed death ligand 1 small molecule inhibition in a humanized mouse model of colorectal cancer results in a significant reduction in tumor size and promotes T cell proliferation. In addition, antigen-specific T and B cell responses from patients with chronic hepatitis B infection are significantly elevated upon programmed death ligand 1 small molecule inhibitor treatment. Taken together, these data identify a mechanism of small molecule-induced programmed death ligand 1 internalization with potential therapeutic implications in oncology and chronic viral infections.

Long-lasting Imprint in the Soluble Inflammatory Milieu despite Early Treatment of Acute Symptomatic Hepatitis C

Background

Treatment with direct-acting antivirals (DAAs) in patients with chronic hepatitis C infection leads to partial restoration of soluble inflammatory mediators (SIMs). In contrast, we hypothesized that early DAA treatment of acute hepatitis C virus (HCV) with DAAs may normalize most SIMs.

Methods

In this study, we made use of a unique cohort of acute symptomatic hepatitis C patients who cleared HCV with a 6-week course of ledipasvir/sofosbuvir. Plasma samples were used for proximity extension assay measuring 92 proteins.

Results

Profound SIM alterations were observed in acute HCV patients, with marked upregulation of interleukin (IL)-6 and CXCL-10, whereas certain mediators were downregulated (eg, monocyte chemoattractant protein-4, IL-7). During treatment and follow-up, the majority of SIMs decreased but not all normalized (eg, CDCP1, IL-18). Of note, SIMs that were downregulated before DAA treatment remained suppressed, whereas others that were initially unchanged declined to lower values during treatment and follow-up (eg, CD244).

Conclusions

Acute hepatitis C was associated with marked changes in the soluble inflammatory milieu compared with both chronic hepatitis patients and healthy controls. Whereas early DAA treatment partly normalized this altered signature, long-lasting imprints of HCV remained.

Long-term immune protection against HBV: associated factors and determinants

In Italy, vaccination against hepatitis B became compulsory for all the newborns and 12-years-old adolescents in 1991. The main purpose of this study was to evaluate the persistence of long-term protection against HBV in medical students of the University of L’Aquila and in postgraduates Medical Doctors (HCWs) working in San Salvatore Hospital. The second aim was to study the variables associated with a protective anti-HBs antibody level, such as age at vaccination, gender, time elapsed from the last dose of vaccination.

Three hundred and forty-two subjects were enrolled from January 2017 to January 2019 and a blood sample was collected to evaluate the levels of serum HBsAg, anti-HBs and anti-HBc. Statistical analysis calculated a multivariable logistic regression model to examine predictors of a protective anti-HBs titer. The larger part (239, 70%) of the students had an anti-HBs titer >10 mIU/mL, those were statistically significant older (26.7 vs 24.5 years, p < .001), vaccinated at age 12 years (83.5% vs 59.9% among vaccinate at infancy, p < .001) and more frequently attending postgraduate medical school (80.8% vs 57.5% among healthcare profession school, p < .001). The multivariable logistic regression model showed that HBV vaccination at age of 12 was significantly and independently associated with protective titers (OR = 10.27, p = .019).

The results agreed with literature on HBV vaccination, confirming the efficacy of vaccination after 20 years. In particular, our results suggest that adolescent administration is the main predictor of a protective title, regardless of gender, course and years since vaccinations.

Pharmacotherapy options for managing hepatitis B in children

INTRODUCTION

To eliminate viral hepatitis by 2030, the World Health Organization (WHO) launched the first global health sector strategy on viral hepatitis, with particular focus given to hepatitis B and C in 2016. To achieve the reduction of mortality in children, it is indispensable to know which children should be treated and how to treat them.

AREA COVERED

In this article, the authors review the antiviral treatment of children with chronic hepatitis B virus (HBV) infection including antivirals available for children with chronic HBV infection.

EXPERT OPINION

The approvals of nucleos(t)ide analogues (NAs) and pegylated interferon (PEG-IFN) for children have lowered a hurdle to the initiation of antiviral treatment in children. The international guidelines use nearly the same criteria of antiviral treatment for children with chronic HBV infection, but the WHO guidelines provide a cautious stance on the antiviral treatment of children. Not only PEG-IFN but also NAs with a high genetic barrier to drug resistance should be the first-line treatment for children. In settings with limited medical resources, NAs can be the first-line treatment for children. Although the concept of an 'immune-tolerant phase' is challenged, evidence is not sufficient to recommend the treatment of HBeAg-positive immune-tolerant children.

High infectious disease burden as a basis for the observed high frequency of asymptomatic SARS-CoV-2 infections in sub-Saharan Africa

Following the coronavirus outbreaks described as severe acute respiratory syndrome (SARS) in 2003 and the Middle East respiratory syndrome (MERS) in 2012, the world has again been challenged by yet another corona virus, named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). SARS-CoV-2 infections were first detected in a Chinese Province in December 2019 and then declared a pandemic by the World Health Organization in March 2020. An infection caused by SARS-CoV-2 may result in asymptomatic, uncomplicated or fatal coronavirus disease 2019 (COVID-19). Fatal disease has been linked with the uncontrolled "cytokine storm" manifesting with complications mostly in people with underlying cardiovascular and pulmonary disease conditions. The severity of COVID-19 disease and the associated mortality has been disproportionately lower in Africa and Asia in comparison to Europe and North America in terms of number of cases and deaths. While persons of colour who live in Europe and North America have been identified as a highly susceptible population due to a combination of several socioeconomic factors and poor access to quality healthcare, this has not been the case in sub-Saharan Africa where inhabitants are even more deprived concerning the said factors. On the contrary, sub-Saharan Africa has recorded the lowest levels of mortality and morbidity associated with the disease, and an overwhelming proportion of infections are asymptomatic. This review discusses the most probable reasons for the significantly fewer cases of severe COVID-19 disease and deaths in sub-Saharan Africa.

Human hepatitis viruses-associated cutaneous and systemic vasculitis

Human hepatitis viruses (HHVs) include hepatitis A virus, hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis delta virus, and hepatitis E virus and can cause liver inflammation in their common human host. Usually, HHV is rapidly cleared by the immune system, following acute HHV invasion. The morbidities associated with hepatitis A virus and hepatitis E virus infection occur shortly after their intrusion, in the acute stage. Nevertheless, the viral infectious process can persist for a long period of time, especially in HBV and HCV infection, leading to chronic hepatitis and further progressing to hepatic cirrhosis and liver cancer. HHV infection brings about complications in other organs, and both acute and chronic hepatitis have been associated with clinical presentations outside the liver. Vascular involvement with cutaneous and systemic vasculitis is a well-known extrahepatic presentation; moreover, there is growing evidence for a possible causal relationship between viral pathogens and vasculitis. Except for hepatitis delta virus, other HHVs have participated in the etiopathogenesis of cutaneous and systemic vasculitis via different mechanisms, including direct viral invasion of vascular endothelial cells, immune complex-mediated vessel wall damage, and autoimmune responses with stimulation of autoreactive B-cells and impaired regulatory T-cells. Cryoglobulinemic vasculitis and polyarteritis nodosa are recognized for their association with chronic HHV infection. Although therapeutic guidelines for HHV-associated vasculitis have not yet been established, antiviral therapy should be initiated in HBV and HCV-related systemic vasculitis in addition to the use of corticosteroids. Plasma exchange and/or combined cyclophosphamide and corticosteroid therapy can be considered in patients with severe life-threatening vasculitis manifestations.

Reversal of Immunity After Clearance of Chronic HCV Infection-All Reset?

Chronic viral infections cause deterioration of our immune system. However, since persistent infections rarely can be eliminated, the reinvigoration capacity of an exhausted immune system has remained largely elusive. Chronic hepatitis C virus (HCV) infection can since some years be effectively cured with novel direct acting antiviral agents. Thus, it is now possible to study reversal of immunity in patients that are cured from a long-lasting chronic infection. We here highlight recent developments in the analysis of various immune cell populations during and after clearance of HCV infection. Surprisingly, whereas reinvigoration of certain immune traits clearly can be seen, many features of immune exhaustion persist over time after viral elimination. Thus, a long-term chronic insult might result in irreversible damage to our immune system. This will be important to consider in therapeutic vaccination efforts against chronic infection and in the development of immunotherapy based strategies against cancer.

Advances in Targeting the Innate and Adaptive Immune Systems to Cure Chronic Hepatitis B Virus Infection

“Functional cure” is being pursued as the ultimate endpoint of antiviral treatment in chronic hepatitis B (CHB), which is characterized by loss of HBsAg whether or not anti-HBs antibodies are present. “Functional cure” can be achieved in <10% of CHB patients with currently available therapeutic agents. The dysfunction of specific immune responses to hepatitis B virus (HBV) is considered the major cause of persistent HBV infection. Thus, modulating the host immune system to strengthen specific cellular immune reactions might help eliminate HBV. Strategies are needed to restore/enhance innate immunity and induce HBV-specific adaptive immune responses in a coordinated way. Immune and resident cells express pattern recognition receptors like TLRs and RIG I/MDA5, which play important roles in the induction of innate immunity through sensing of pathogen-associated molecular patterns (PAMPs) and bridging to adaptive immunity for pathogen-specific immune control. TLR/RIG I agonists activate innate immune responses and suppress HBV replication in vitro and in vivo, and are being investigated in clinical trials. On the other hand, HBV-specific immune responses could be induced by therapeutic vaccines, including protein (HBsAg/preS and HBcAg), DNA, and viral vector-based vaccines. More than 50 clinical trials have been performed to assess therapeutic vaccines in CHB treatment, some of which display potential effects. Most recently, using genetic editing technology to generate CAR-T or TCR-T, HBV-specific T cells have been produced to efficiently clear HBV. This review summarizes the progress in basic and clinical research investigating immunomodulatory strategies for curing chronic HBV infection, and critically discusses the rather disappointing results of current clinical trials and future strategies.

Feasibility and efficacy of home rectal irrigation in neonates and early infancy with Hirschsprung disease

PURPOSE

A single-stage pull-through (SSPT) is the most commonly performed procedure for Hirschsprung disease (HSCR) and has been shown to be better than multi-stage procedures. However, performing a SSPT in the neonatal period or early in infancy is a risk factor for an inaccurate diagnosis, post-operative enterocolitis, and a protracted post-operative recovery. The present study was primarily designed to evaluate the feasibility and efficacy of home rectal irrigation in the neonatal period and early in infancy, followed by a delayed and planned SSPT in a prospective cohort with HSCR.

METHODS

Between January 2014 and December 2016, a total of 147 neonates diagnosed with HSCR were enrolled in the study. Six patients were excluded as a result of ganglion cells found in second rectal biopsies after the neonatal period. One hundred twenty-two patients successfully underwent 2-4 months of home rectal irrigation during the neonatal period, followed by a SSPT procedure after the neonatal period (group A, n = 122). Nineteen patients were not candidates for home rectal irrigation, and thus, colostomies were performed during the neonatal period followed by multi-stage procedures after the neonatal period (group B, n = 19). One hundred twenty-two healthy children, age- and gender-matched to group A were enrolled as the healthy control group for assessment of nutrition status (group C, n = 122). The birth weight, gender ratio, aganglionic segment, age, and Hirschsprung-associated enterocolitis (HAEC) score at the time of HSCR diagnosis were measured to evaluate the feasibility of home rectal irrigation in neonates and early in infancy. The nutritional indices, including weight, body length, serum albumin, serum prealbumin, serum retinol-binding protein, and incidence of HAEC after 2-4 successful home rectal irrigation, were used to assess the efficacy of home rectal irrigation. Anastomotic strictures or leakage, perianal excoriation, frequency of defecation, and morbidity of post-operative HAEC were recorded to evaluate the beneficial effects to pull through (PT), which were facilitated by home rectal irrigation.

RESULTS

Higher HAEC scores and older age at the time of diagnosis of HSCR were associated with group B, compared to group A (4.34 ± 1.25 vs. 11.0 ± 2.56 [t = 18.20, p < 0.05] and 2.8 ± 1.46 days vs. 12.1 ± 5.3 days [t = 16.10, p < 0.05], respectively). The ratio of rectosigmoid HSCR to non-rectosigmoid HSCR was higher in group A than group B (104/18 vs. 4/15 [χ² = 34.29, p < 0.05]). There were no differences in birth weight, weight at the time of diagnosis of HSCR, and gender ratio between groups A and B. There were no differences in birth weight, birth length, post-home rectal irrigation age, post-home rectal irrigation weight, post-home rectal irrigation length, and post-home rectal irrigation serum albumin between groups A and C (3.47 ± 0.42 kg vs. 3.48 ± 0.40 kg [t = 0.10, p > 0.05], 50.02 ± 0.49 cm vs. 50.05 ± 0.46 cm [t = 0.61, p > 0.05], 98.59 ± 13.34 days vs. 97.83 ± 13.58 days [t = 0.44, p > 0.05], 6.77 ± 0.66 kg vs. 6.97 ± 0.87 kg [t = 1.95, p > 0.05], 61.55 ± 2.14 cm vs. 61.70 ± 2.07 cm [t = 0.59, p > 0.05], and 41.78 ± 2.42 g/L vs. 41.85 ± 2.37 g/L [t = 0.22, p > 0.05], respectively). The rate of HAEC in the period of home rectal irrigation in group A was low; however, the post-home rectal irrigation serum prealbumin level and retinol-binding protein were significantly lower in group A than group C (0.15 ± 0.04 g/L vs. 0.17 ± 0.05 g/L [t = 3.50, p < 0.05] and 22.51 ± 7.53 g/L vs. 30.57 ± 9.26 g/L [t = 7.46, p < 0.05], respectively). There were no anastomotic strictures or leakage after definitive PT performed in group A. The frequency of defecation ranged from 2-6 times per day, 10 patients had perianal excoriation 3 months after PT, and 11 patients had post-operative HAEC during 6 months of follow-up after PT.

CONCLUSION

Home rectal irrigation in neonates and early in infancy, followed by a delayed and planned SSPT is feasible and effective in patients with HSCR, and could be beneficial to definitive PT. However, for patients with an extended aganglionic segment, older age, or high HAEC score at the time of diagnosis of HSCR, rectal irrigation maybe not suitable.

TRIAL REGISTRATION

This was a prospective comparative study designed to evaluate the effects of home rectal irrigation for facilitating and enhancing recovery after PT, and was registered at Clinical Trials.gov as NCT02776176.

Host Genetic Determinants of Hepatitis B Virus Infection

Chronic hepatitis B virus (HBV) infection is still a major health problem worldwide. Recently, a great number of genetic studies based on single nucleotide polymorphisms (SNPs) and genome-wide association studies have been performed to search for host determinants of the development of chronic HBV infection, clinical outcomes, therapeutic efficacy, and responses to hepatitis B vaccines, with a focus on human leukocyte antigens (HLA), cytokine genes, and toll-like receptors. In addition to SNPs, gene insertions/deletions and copy number variants are associated with infection. However, conflicting results have been obtained. In the present review, we summarize the current state of research on host genetic factors and chronic HBV infection, its clinical type, therapies, and hepatitis B vaccine responses and classify published results according to their reliability. The potential roles of host genetic determinants of chronic HBV infection identified in these studies and their clinical significance are discussed. In particular, HLAs were relevant for HBV infection and pathogenesis. Finally, we highlight the need for additional studies with large sample sizes, well-matched study designs, appropriate statistical methods, and validation in multiple populations to improve the treatment of HBV infection.

Ex vivo Detection and Characterization of Hepatitis B Virus-Specific CD8+ T Cells in Patients Considered Immune Tolerant

In this study, we aimed to detect and characterize ex vivo virus-specific CD8⁺ T cells in patients with immune-tolerant hepatitis B virus (HBV) infection. We investigated a Korean chronic hepatitis B cohort composed of 15 patients in the immune-tolerant phase, 17 in the immune-active phase, and 13 under antiviral treatment. We performed enzyme-linked immunospot (ELISpot) assays ex vivo and intracellular cytokine staining after in vitro culture. We also performed ex vivo multimer staining assays and examined the expression of programmed death-1 (PD-1) and CD127 in pentamer-positive cells. Ex vivo ELISpot revealed that HBV-specific T cell function was weaker in immune-tolerant patients than in those under antiviral treatment. In vitro culture of peripheral blood mononuclear cells for 10 days revealed that HBV-specific CD8⁺ T cells produced interferon-γ in some immune-tolerant patients. We detected HBV-specific CD8⁺ T cells ex vivo (using the HBV core_18-27 pentamer) in patients from all three groups. The PD-1⁺ subset of pentamer⁺ CD8⁺ T cells was smaller ex vivo in the immune-tolerant phase than in the immune-active phase or under antiviral treatment. Interestingly, the proportion of PD-1⁺ CD8⁺ T cells in HBV-specific CD8⁺ T cells correlated with patient age when all enrolled patients were analyzed. Overall, HBV-specific CD8⁺ T cells are present in patients considered as immune-tolerant, although their ex vivo functionality is significantly weaker than that in patients under antiviral treatment (P < 0.05). Despite the high viral load, the proportion of PD-1 expression in HBV-specific CD8⁺ T cells is lower in the immune-tolerant phase than in other phases. Our results indicate appropriate stimulation may enhance the effector function of HBV-specific CD8⁺ T cells in patients considered as being in the immune-tolerant phase.

Endogenously Expressed Antigens Bind Mammalian RNA via Cationic Domains that Enhance Priming of Effector CD8 T Cells by DNA Vaccination

Hepatitis B virus (HBV) core (HBV-C) antigens with homologous or heterologous HIV-tat48-57-like (HBV-C149tat) cationic domains non-specifically bind cellular RNA in vector-transfected cells. Here, we investigated whether RNA-binding to cationic domains influences the immunogenicity of endogenously expressed antigens delivered by DNA vaccination. We initially evaluated induction of HBV-C (K^b/C93)-specific CD8⁺ T cell responses in C57BL/6J (B6) and 1.4HBV-S^mut transgenic (tg) mice that harbor a replicating HBV genome in hepatocytes by DNA immunization. RNA-binding HBV-C and HBV-C149tat antigens moderately enhanced K^b/C93-specific CD8⁺ T cells in B6 mice as compared with RNA-free HBV-C149 antigen (lacking cationic domains). However, only the RNA-binding antigens elicited K^b/C93-specific CD8⁺ T cells that inhibited HBV replication in 1.4HBV-S^mut tg mice. Moreover, RNA-binding to designer antigens, which express a K^b/p15E epitope from an endogenous murine leukemia virus-derived tumor-specific gp70 protein, was crucial to prime tumor-rejecting effector CD8⁺ T cells in B6 mice. Antigen-bound endogenous RNAs function as a Toll-like receptor 7 (TLR-7) ligand and stimulated priming of K^b/p15E-specific CD8⁺ T cells in B6, but not TLR-7^−/−, mice. Antigen-bound cellular RNAs thus function as an endogenous natural adjuvant in in vivo vector-transfected cells, and thus are an attractive tool to induce and/or enhance effector CD8⁺ T cell responses directed against chronic viral infections or tumor self-antigens by DNA vaccination.

Clonal anergy of CD117+chB6+ B cell progenitors induced by avian leukosis virus subgroup J is associated with immunological tolerance

BACKGROUND

The pathogenesis of immunological tolerance caused by avian leukosis virus subgroup J (ALV-J), an oncogenic retrovirus, is largely unknown.

RESULTS

In this study, the development, differentiation, and immunological capability of B cells and their progenitors infected with ALV-J were studied both morphologically and functionally by using a model of ALV-J congenital infection. Compared with posthatch infection, congenital infection of ALV-J resulted in severe immunological tolerance, which was identified as the absence of detectable specific antivirus antibodies. In congenitally infected chickens, immune organs, particularly the bursa of Fabricius, were poorly developed. Moreover, IgM-and IgG-positive cells and total immunoglobulin levels were significantly decreased in these chickens. Large numbers of bursa follicles with no differentiation into cortex and medulla indicated that B cell development was arrested at the early stage. Flow cytometry analysis further confirmed that ALV-J blocked the differentiation of CD117+chB6+ B cell progenitors in the bursa of Fabricius. Furthermore, both the humoral immunity and the immunological capability of B cells and their progenitors were significantly suppressed, as assessed by (a) the antibody titres against sheep red blood cells and the Marek's disease virus attenuated serotype 1 vaccine; (b) the proliferative response of B cells against thymus-independent antigen lipopolysaccharide (LPS) in the spleen germinal centres; and (c) the capacities for proliferation, differentiation and immunoglobulin gene class-switch recombination of B cell progenitors in response to LPS and interleukin-4(IL-4) in vitro.

CONCLUSIONS

These findings suggested that the anergy of B cells in congenitally infected chickens is caused by the developmental arrest and dysfunction of B cell progenitors, which is an important factor for the immunological tolerance induced by ALV-J.

5'-triphosphate siRNA targeting HBx elicits a potent anti-HBV immune response in pAAV-HBV transfected mice

RNA with 5'-triphosphate (3p-RNA) is recognized by RNA sensor RIG-I (retinoic acid-inducible gene I protein). Previously, we reported that small interfering RNA targeting HBx (3p-siHBx) could confer potent anti-hepatitis B virus (HBV) efficacy via HBx silencing and RIG-I activation. However, the characteristics of innate and adaptive immunity especially exhaustion profiles in the liver microenvironment in response to 3p-siHBx therapy have not been fully elucidated. Here, we observed that 3p-siHBx more significantly inhibited HBV replication in vivo. 3p-siHBx enhanced natural killer (NK) cell activation with KLRG1 and CD69 upregulation and interferon (IFN)-γ secretion. 3p-siHBx significantly reversed the exhaustion phenotype of CD8⁺ T cells, and augmented CD8⁺ T cell activation and function. Importantly, 3p-siHBx disrupted the differentiation of myeloid-derived suppressor cells (MDSC) and regulatory T cells (Treg), accompanied by the reduction of the immunosuppressive cytokines interleukin (IL)-10 and transforming growth factor (TGF)-β. 3p-siHBx also enhanced dendritic cell maturation. Further investigation showed that RIG-I was involved in 3p-siHBx-induced IFN-α, IFN-β, and IFN-λ production. Moreover, RIG-I activation in HBV⁺ hepatocytes would improve the recruitment of CD8⁺ T cells and NK cells. These results reveal that 3p-siHBx therapy can improve the immune microenvironment in HBV-carrier liver and inhibit HBV replication, indicating the potential utility of RIG-I ligands as molecular adjuvants for viral vaccines or candidate drugs.

From infancy and beyond… ensuring a lifetime of hepatitis B virus (HBV) vaccine-induced immunity

Despite the long-term efficacy and immune persistence observed following HBV vaccination of infants, the need for a booster dose following infant immunization continues to be deliberated. Evidence from HBV booster dose response studies and long-term immunization program reviews are the basis for the recommendation that a vaccine booster is not necessary. However, further studies continue to emerge and highlight the need for standardization among observational studies in order to appropriately compare outcomes. There is an assumption that neonatal and infant (within 12 months of age) vaccine immune responses are equivalent; however, evidence exists for distinct vaccine responses within the first year of life. HBV vaccine programs have evolved over time, particularly regarding the type and dosage of vaccine used. Several universal neonatal immunization programs initially incorporated a 2.5 μg dosage (Recombivax-HB, Merck). This dosage has been shown in multiple long-term studies and meta-analyses to be associated with a lower primary response, decreased antibody persistence over time, and a reduced booster response 10 to 20 years following immunization. Ongoing surveillance of this and other HBV neonatally-vaccinated populations, particularly in low endemic regions, is necessary to understand the impact on long-term protection in order to ensure lifelong protection against hepatitis B infection.

Infectious Agents as Stimuli of Trained Innate Immunity

The discoveries made over the past few years have modified the current immunological paradigm. It turns out that innate immunity cells can mount some kind of immunological memory, similar to that observed in the acquired immunity and corresponding to the defense mechanisms of lower organisms, which increases their resistance to reinfection. This phenomenon is termed trained innate immunity. It is based on epigenetic changes in innate immune cells (monocytes/macrophages, NK cells) after their stimulation with various infectious or non-infectious agents. Many infectious stimuli, including bacterial or fungal cells and their components (LPS, β-glucan, chitin) as well as viruses or even parasites are considered potent inducers of innate immune memory. Epigenetic cell reprogramming occurring at the heart of the phenomenon may provide a useful basis for designing novel prophylactic and therapeutic strategies to prevent and protect against multiple diseases. In this article, we present the current state of art on trained innate immunity occurring as a result of infectious agent induction. Additionally, we discuss the mechanisms of cell reprogramming and the implications for immune response stimulation/manipulation.