Interconnection of cellular autophagy and endosomal vesicle trafficking and its role in hepatitis B virus replication and release

Hepatitis B virus(HBV)produces and releases various particle types,including complete virions,subviral particles with envelope proteins,and naked capsids.Recent studies demonstrate that HBV exploits distinct intracellular membrane trafficking pathways,including the endosomal vesicle trafficking and autophagy pathway,to assemble and release viral and subviral particles.Herein,we summarize the findings about the distinct roles of autophagy and endosomal membrane trafficking and the interaction of both pathways in HBV replication,assembly,and release.

Interferon-α response in chronic hepatitis B-transfected HepG2.2.15 cells is partially restored by lamivudine treatment

AIM: To characterize the IFN-response and its modul- ation by the antiviral compound lamivudine in HBV- transfected HepG2.2.15 cells. METHODS: HepG2.2.15 and HepG2 cells were stimulated with various concentrations of IFN-a2a in the presence or absence of lamivudine. Then, total RNA was extracted and analysed by customised cDNA arrays and northern blot for interferon-inducible genes (ISGs). In addition, cellular proteins were extracted for EMSA and western blot. HBV replication was assessed by southern blot or ELISAs for HBsAg and HBeAg. RESULTS: Two genes (MxA, Cig5) with completely abolished and 4 genes (IFITM1, -2, -3, and 6-16) with partially reduced IFN-responses were identified in HepG2.2.15 cells. In 2 genes (IFITM1, 6-16), the response to IFN-a could be restored by treatment with lamivudine. This effect could not be explained by a direct modulation of the Jak/Stat signalling pathway since EMSA and western blot experiments revealed no suppression of Stat1 activation and ISGF3 formation after stimulation with IFN-a in HepG2.2.15 compared to HepG2 cells. CONCLUSION: These results are consistent with the assumption that chronic hepatitis B may specifically modulate the cellular response to IFN by a selective blockage of some ISGs. Antiviral treatment with lamivudine may partially restore ISG expression by reducing HBV gene expression and replication.

New therapeutic vaccination strategies for the treatment of chronic hepatitis B

Chronic hepatitis B virus(CHB) is currently treated with either interferon-based or nucleot(s)idebased antiviral therapies.However,treatment with pegylated interferon alpha results in a durable antiviral response in only about 30%patients and is associated with side effects.Most patients receiving nucleot(s)ide analogue treatment do not establish long-term,durable control of Infection and have rebounding viremia after cessation of therapy.Thus,novel therapy strategies are necessary to achieve the induction of potent and durable antiviral immune responses of the patients which can maintain long-term control of viral replication.Therapeutic vaccination of HBV carriers is a promising strategy for the control of hepatitis B.Here the authors review new therapeutic vaccination strategies to treat chronic hepatitis B which may be introduced for patient treatment in the future.

A Case of Hepatitis B Reactivation due to the Hepatitis B Virus Escape Mutant in a Patient undergoing Chemotherapy

A 62-year-old man had chronic hepatitis B virus (HBV) infection and was diagnosed with liver cirrhosis.At the time of diagnosis the patient's virologic markers were positive for hepatitis B surface antigen (HBsAg),antibody to hepatitis B e antigen (anti-HBe) and antibody to hepatitis B core antigen (anti-HBc),while antibody to hepatitis B surface antigen (anti-HBs) and HBV DNA were negative.Later the patient received chemotherapy for malignancy.However,this was interrupted due to elevated liver enzymes.At the same time HBV DNA became positive.Lamivudine (LMV) therapy was administered immediately.However,the levels of serum aminotransferase and total bilirubin (TB) were still rising.Finally the patient died of fulminant hepatic failure.A sequence revealed HBV genotype C (HBsAg subtype adw) with immune escape mutations,F8L,S34L,F41S,G44V,F93C,V96G,L110I,C149Y and F161Y.The high morbidity and mortality of this complication is one of the major obstacles to completing the standard treatment for malignancy in HBV carriers.Therefore,the relative risk of antiviral prophylactic failure should be further assessed and the optimal strategy for antiviral prophylaxis in HBsAg-positive patients with oncologic and hematologic malignancies undergoing chemotherapy should be revised.

A Case of Hepatitis B Reactivation in an Anti-HBs Positive,Anti-HBc Positive non-Hodgkin’s Lymphoma Patient

Dear Editor,We report a case of HBV reactivation in an anti-HBs positive, anti-HBc positive non-Hodgkin’s lymphoma patient. Hepatitis B virus (HBV) reactivation is a well-recognized complication of patients undergoing chemotherapy or immunosuppressive therapy for lymphomas. The presence of antibodies to the

Regulation of Hepatitis C Virus Replication and Gene Expression by the MAPK-ERK Pathway

The mitogen activated protein kinases-extracellular signal regulated kinases (MAPK-ERK) pathway is involved in regulation of multiple cellular processes including the cell cycle. In the present study using a Huh7 cell line Con1 with an HCV replicon, we have shown that the MAPK-ERK pathway plays a significant role in the modulation of HCV replication and protein expression and might influence IFN-α signalling. Epithelial growth factor (EGF) was able to stimulate ERK activation and decreased HCV RNA load while a MAPK-ERK pathway inhibitor U0126 led to an elevated HCV RNA load and higher NS5A protein amounts in Con1 cells. It could be further demonstrated that the inhibition of the MAPK-ERK pathway facilitated the translation directed by the HCV internal ribosome entry site. Consistently, a U0126 treatment enhanced activity of the HCV reporter replicon in transient transfection assays. Thus, the MAPK-ERK pathway plays an important role in the regulation of HCV gene expression and replication. In addition, cyclin-dependent kinases (CDKs) downstream of ERK may also be involved in the modulation of HCV replication since roscovitine, an inhibitor of CDKs had a similar effect to that of U0126. Modulation of the cell cycle progression by cell cycle inhibitor or RNAi resulted consistently in changes of HCV RNA levels. Further, the replication of HCV replicon in Con1 cells was inhibited by IFN-α. The inhibitory effect of IFN-α could be partly reversed by pre-incubation of Con-1 cells with inhibitors of the MAPK-ERK pathway and CDKs. It could be shown that the MAPK-ERK inhibitors are able to partially modulate the expression of interferon-stimulated genes.

Interaction of viruses with host immune system and immunomodulation in chronic viral infections

The WHO estimates that almost500 million people world-wide are chronically infected with hepatitis B and C viruses(HBV and HCV)and human immune deficiency virus(HIV).During the recent years,significant progress was made in treatment of chronic infection with HBV,HCV,and HIV,mainly based on directly antiviral agents.However,

Recent Advances in Research on Hepadnaviral Infection in the Woodchuck Model

The woodchuck model is an excellent animal model to study hepadnaviral infection. The new progresses in this model made possible to examine the T-cell mediated immune responses in acute and chronic hepadnaviral infection. Recently, a new assay for cytotoxic T-cells based on detection of CD107 was established for the woodchuck model. In addition, new immunotherapeutic approaches based on combination of potent antiviral treatment and DNA-protein vaccines were proven to be useful for treatment of chronic hepatitis B.

Molecular Characterization of Duck Hepatitis B Virus Isolated from Hubei Brown Ducks

The objective of this study was to characterize the genome structure of duck hepatitis B virus （DHBV） isolated from Hubei brown ducks. The natural carrier rate of DHBV in adult ducks from Hubei area was investigated and the DHBV DNA-positive serum screened out. The complete genome of a DHBV strain was amplified by polymerase chain reaction （PCR） and cloned into T vector and sequenced. The results showed that the carrier rate of DHBV in Hubei brown ducks was 10 % This strain （GenBank accession number DQ276978） had a genome of 3024 nucleotides with three overlapping open reading frames encoding the surface, core and polymerase proteins respectively. Comparison of the strain with 17 DHBV strains registered in GenBank revealed a homology from 89.3 % to 93.5 % at the nucleotide level. The sequences of the structural and functional domains of these proteins were highly conserved. The strain was found to share more signature amino acids in the polymerase genes with the ＂Chinese＂ DHBV strains than those of the ＂Western＂ country strains. This finding was also corroborated by a phylogenetic tree analysis. Therefore, the DQ276978 might belong to a subtype of the Chinese DHBV strains.

mTOR Signaling: The Interface Linking Cellular Metabolism and Hepatitis B Virus Replication

Mammalian target of rapamycin(m TOR) is a conserved Ser/Thr kinase that includes m TOR complex(m TORC) 1 and m TORC2. The m TOR pathway is activated in viral hepatitis, including hepatitis B virus(HBV) infection-induced hepatitis.Currently, chronic HBV infection remains one of the most serious public health issues worldwide. The unavailability of effective therapeutic strategies for HBV suggests that clarification of the pathogenesis of HBV infection is urgently required. Increasing evidence has shown that HBV infection can activate the m TOR pathway, indicating that HBV utilizes or hijacks the m TOR pathway to benefit its own replication. Therefore, the m TOR signaling pathway might be a crucial target for controlling HBV infection. Here, we summarize and discuss the latest findings from model biology research regarding the interaction between the m TOR signaling pathway and HBV replication.

SARS-CoV-2-specific T cell responses wane profoundly in convalescent individuals 10 months after primary infection

A key question in the coronavirus disease 2019(COVID-19)pandemic is the duration of specific T cell responses against the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)post primary infection,which is difficult to address due to the large-scale COVID-19 vaccination and re-exposure to the virus.Here,we conducted an analysis of the long-term SARS-CoV-2-specific T cell responses in a unique cohort of convalescent individuals(CIs)that were among the first to be infected worldwide and without any possible antigen re-exposure since then.The magnitude and breadth of SARS-CoV-2-specific T cell responses correlated inversely with the time that had elapsed from disease onset and the age of those CIs.The mean magnitude of SARS-CoV-2-specific CD4 and CD8 T cell responses decreased about 82%and 76%,respectively,over the time period of ten months after infection.Accordingly,the longitudinal analysis also demonstrated that SARS-CoV-2-specific T cell responses waned significantly in 75%of CIs during the follow-up.Collectively,we provide a comprehensive characterization of the long-term memory T cell response in CIs,suggesting that robust SARS-CoV-2-specific T cell immunity post primary infection may be less durable than previously expected.

Contribution of Toll-like receptors to the control of hepatitis B virus infection by initiating antiviral innate responses and promoting specific adaptive immune responses

It is well accepted that adaptive immunity plays a key role in the control of hepatitis B virus （HBV） infection. In contrast, the contribution of innate immunity has only received attention in recent years. Toll-like receptors （TLRs） sense pathogen-associated molecule patterns and activate antiviral mechanisms, including intracellular antiviral pathways and the production of antiviral effector interferons （IFNs） and pro-inflammatory cytokines. Experimental results from in vitroand in vivo models have demonstrated that TLRs mediate the activation of cellular signaling pathways and the production of antiviral cytokines, resulting in a suppression of HBV replication. However, HBV infection is associated with downregulation of TLR expression on host cells and blockade of the activation of downstream signaling pathways. In primary HBV infection, TLRs may slow down HBV infection, but contribute only indirectly to viral clearance. Importantly, TLRs may modulate HBV-specific T- and B-cell responses in vivo, which are essential for the termination of HBV infection. Thus, TLR agonists are promising candidates to act as immunomodulators for the treatment of chronic HBV infection. Antiviral treatment may recover TLR expression and function in chronic HBV infection and may increase the efficacy of therapeutic approaches based on TLR activation. A combined therapeutic strategy with antiviral treatment and TLR activation could facilitate the restoration of HBV-specific immune responses and thereby, achieve viral clearance in chronically infected HBV patients.

Construction and Identification of a Human Liver Specific MicroRNA Eukaryotic Expression Vector

MiR-122 is one of the non-coding RNAs which showed its effects on the lipo-metablism, virus infection and HCC forming through regulation of liver gene expression. Its eukaryotic expression vector was constructed by using pSuper which was widely applied in the siRNA expression. The precursor of human miR-122 gene was amplified by polymerase chain reaction （PCR） from the human genomic DNA. The positive clones were screened by PCR and restriction enzyme digestion. The new expression vector of miR-122 was named pHsa-m122. PHsa-m122 and its controls were transfected to HepG2 cells. The miR-122 expression activity was evaluated by GFP122i sensor reporter plasmid through fluorescence detection and Western blot. It was shown that the fluorescence intensity of GFP122si and pHsa-m122 co-transfection group was weaker than that of the controls, so the functional activity of expressed miR-122 was detected. When HepG2 cells were co-transfected with HBV1.3 and pHsa-m122 plasmids, the results showed miR-122 may down-regulate the gene expression of HBV. The human liver specific microRNA eukaryotic expression vector of miR-122 was constructed successfully, which may facilitate further study of its function in the development of liver virus infection diseases and HCC. Cellular ＆ Molecular Immunology.

The role of micro RNAs in hepatocyte metabolism and hepatitis B virus replication

Though efficient vaccines against hepatitis B virus(HBV) and antiviral therapies are available,chronic HBV infection is still a global health problem. The process of HBV infection and HBV life cycle are extensively studied in last decades, however, the mechanisms of HBV-induced alterations of host cell metabolisms and host factors involved in modulating of viral replication are not fully understood. Thus, it is an important issue to examine these specific HBV-host interactions for development of novel strategies for antiviral therapies. Recently, microRNAs(miRNAs), a class of post-transcriptional regulatory small RNA, seem to be the relevant fine tuning factors of various cellular activities and pathways, including cell growth, metabolism, and viral replication. In this review, we summarize the up to date knowledge concerning the virus-host interactions and emphasizing on the role of miRNAs in regulation of HBV replication and host cell metabolism.

Complementation of Wild-Type and Drug-Resistant Hepatitis B Virus Genomes to Maintain Viral Replication and Rescue Virion Production under Nucleos(t)ide Analogs

As the open reading frames of hepatitis B virus(HBV)genomes are overlapping,resistance mutations(MTs)in HBV polymerase may result in stop codon MTs in hepatitis B surface proteins,which are usually detected as a mixed population with wild-type(WT)HBV.The question was raised how the coexistence of nucleos(t)ide analogs(NAs)resistance MTs and WT sequences affects HBV replication.In the present study,HBV genomes with frequently detected reverse transcriptase(RT)/surface truncation MTs,rtA181T/sW172^*,rtV191I/sW182^*and rtM204I/sW196^*,were phenotypically characterized alone or together with their WT counterparts in different ratios by transient transfection in the absence or presence of Nas.In the absence of Nas,RT/surface truncation MTs impaired the expression and secretion of HBV surface proteins,and had a dose-dependent negative effect on WT HBV virion secretion.However,in the presence of Nas,coexistence of MTs with WT maintained viral replication,and the presence of WT was able to rescue the production of MT HBV virions.Our findings reveal that complementation of WT and MT HBV genomes is highly effective under drug treatment.

Hepatitis B virus is degraded by autophagosome-lysosome fusion mediated by Rab7 and related components

Dear Editor,With an estimated 240 million chronically infected people worldwide,hepatitis B virus(HBV)infection is a major public health problem(Schweitzer et al.,2015).Despite more than 30 years of in tense research,many aspects of the HBV life cycle still remain unknown.

The IL-1R/TLR signaling pathway is essential for efficient CD8+ T-cell responses against hepatitis B virus in the hydrodynamic injection mouse model

The outcome of hepatitis B viral(HBV)infection is determined by the complex interactions between replicating HBV and the immune system.While the role of the adaptive immune system in the resolution of HBV infection has been studied extensively,the contribution of innate immune mechanisms remains to be defined.Here we examined the role of the interleukin-1 receptor/Toll-like receptor(IL-1R/TLR)signaling pathway in adaptive immune responses and viral clearance by exploring the HBV mouse model.Hydrodynamic injection with a replication-competent HBV genome was performed in wild-type mice(WT)and a panel of mouse strains lacking specific innate immunity component expression.We found higher levels of HBV protein production and replication in Tlr2^(−/−),Tlr23479^(−/−),3d/Tlr24^(−/−),Myd88/Trif^(−/−)and Irak4^(−/−)mice,which was associated with reduced HBV-specific CD8+T-cell responses in these mice.Importantly,HBV clearance was delayed for more than 2 weeks in 3d/Tlr24^(−/−),Myd88/Trif^(−/−)and Irak4^(−/−)mice compared to WT mice.HBV-specific CD8+T-cell responses were functionally impaired for producing the cytokines IFN-γ,TNF-αand IL-2 in TLR signaling-deficient mice compared to WT mice.In conclusion,the IL-1R/TLR signaling pathway might contribute to controlling HBV infection by augmenting HBV-specific CD8+T-cell responses.

Discrimination of False Negative Results in RT-PCR Detection of SARS-CoV-2 RNAs in Clinical Specimens by Using an Internal Reference

Reverse transcription-polymerase chain reaction(RT-PCR)is an essential method for specific diagnosis of SARS-CoV-2 infection.Unfortunately,false negative test results are often reported.In this study,we attempted to determine the principal causes leading to false negative results of RT-PCR detection of SARS-CoV-2 RNAs in respiratory tract specimens.Multiple sputum and throat swab specimens from 161 confirmed COVID-19 patients were tested with a commercialfluorescent RT-PCR kit targeting the ORF1 ab and N regions of SARS-CoV-2 genome.The RNA level of a cellular housekeeping gene ribonuclease P/MRP subunit p30(RPP30)in these specimens was also assessed by RT-PCR.Data for a total of 1052 samples were retrospectively re-analyzed and a strong association between positive results in SARS-CoV-2 RNA tests and high level of RPP30 RNA in respiratory tract specimens was revealed.By using the ROC-AUC analysis,we identified Ct cutoff values for RPP30 RT-PCR which predicted false negative results for SARS-CoV-2 RT-PCR with high sensitivity(95.03%–95.26%)and specificity(83.72%–98.55%)for respective combination of specimen type and ampli-fication reaction.Using these Ct cutoff values,false negative results could be reliably identified.Therefore,the presence of cellular materials,likely infected host cells,are essential for correct SARS-CoV-2 RNA detection by RT-PCR in patient specimens.RPP30 could serve as an indicator for cellular content,or a surrogate indicator for specimen quality.In addition,our results demonstrated that false negativity accounted for a vast majority of contradicting results in SARS-CoV-2 RNA test by RT-PCR.

Patients with SARS-CoV-2 and HBV coinfection are at risk of greater liver injury

To date,it remains unclear if severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)co-infection exacerbates liver injury in patients with chronic hepatitis B virus(HBV)infection.In this study,we present a retrospective study of 133 hospitalized confirmed mild coronavirus disease 2019(COVID-19)cases,including 116 patients with COVID-19 with negative serum hepatitis B antigen and 17 HBV inactive carriers with COVID-19.We found that there were no significant differences for the discharge rate or duration of hospitalization be-tween the two groups.However,inactive HBV carriers with SARS-CoV-2 co-infection are at a higher risk of abnormal liver function tests.The enhanced liver injury induced by SARS-CoV-2 and HBV co-infection was identified as the hepatocyte type rather than the cholangiocyte type.Moreover,the inflammatory response,including abnormal lactate dehydrogenase,D-dimer and interleukin-6 production,may contribute to this injury following SARS-CoV-2 co-infection.Collectively,SARS-CoV-2 and HBV co-infection exacerbates liver function of the pa-tients with COVID-19.

Inducible Rubicon facilitates viral replication by antagonizing interferon production

The RUN domain Beclin-1-interacting cysteine-rich-containing(Rubicon)protein is involved in the maturation step of autophagy and the endocytic pathway as a Beclin-1-binding partner,but little is known regarding the role of Rubicon during viral infection.Here,we performed functional studies of the identified target in interferon(IFN)signaling pathways associated with Rubicon to elucidate the mechanisms of viral resistance to IFN.The Rubicon protein levels were elevated in peripheral blood mononuclear cells,sera and liver tissues from patients with hepatitis B virus(HBV)infection relative to those in healthy individuals.Assays of the overexpression and knockdown of Rubicon showed that Rubicon significantly promoted HBV replication.In addition,Rubicon knockdown resulted in the inhibition of enterovirus 71,influenza A virus and vesicular stomatitis virus.The expression o0f Rubicon led to the suppression of virus-induced type-I interferon(IFN-αand IFN-β)and type-III interferon(IFN-λ1).Translocation of activated IRF3 and IRF7 from the cytoplasm to the nucleus was involved in this process,and the NF-κB essential modulator(NEMO),a key factor in the IFN pathway,was the target with which Rubicon interacted.Our results reveal a previously unrecognized function of Rubicon as a virus-induced protein that binds to NEMO,leading to the inhibition of type-I interferon production.Rubicon thus functions as an important negative regulator of the innate immune response,enhances viral replication and may play a role in viral immune evasion.