A male-ABCD algorithm for hepatocellular carcinoma risk prediction in HBs Ag carriers

Objective: Hepatocellular carcinoma(HCC) development among hepatitis B surface antigen(HBs Ag) carriers shows gender disparity, influenced by underlying liver diseases that display variations in laboratory tests. We aimed to construct a risk-stratified HCC prediction model for HBs Ag-positive male adults.Methods: HBs Ag-positive males of 35-69 years old(N=6,153) were included from a multi-center populationbased liver cancer screening study. Randomly, three centers were set as training, the other three centers as validation. Within 2 years since initiation, we administrated at least two rounds of HCC screening using Bultrasonography and α-fetoprotein(AFP). We used logistic regression models to determine potential risk factors,built and examined the operating characteristics of a point-based algorithm for HCC risk prediction.Results: With 2 years of follow-up, 302 HCC cases were diagnosed. A male-ABCD algorithm was constructed including participant's age, blood levels of GGT(γ-glutamyl-transpeptidase), counts of platelets, white cells,concentration of DCP(des-γ-carboxy-prothrombin) and AFP, with scores ranging from 0 to 18.3. The area under receiver operating characteristic was 0.91(0.90-0.93), larger than existing models. At 1.5 points of risk score,26.10% of the participants in training cohort and 14.94% in validation cohort were recognized at low risk, with sensitivity of identifying HCC remained 100%. At 2.5 points, 46.51% of the participants in training cohort and 33.68% in validation cohort were recognized at low risk with 99.06% and 97.78% of sensitivity, respectively. At 4.5 points, only 20.86% of participants in training cohort and 23.73% in validation cohort were recognized at high risk,with positive prediction value of 22.85% and 12.35%, respectively.Conclusions: Male-ABCD algorithm identified individual's risk for HCC occurrence within short term for their HCC precision surveillance.

Host cyclophilin A facilitates SARS-CoV-2 infection by binding and stabilizing spike on virions

Dear Editor,The novel coronavirus SARS-CoV-2 rapidly evolutes to increase its infectivity and transmissibility,facilitates its immune escape,impairs vaccine efficacy,and currently causes repeated infections in human,which is mainly determined by the accumulated mutations in spike(S).1 Transmembrane S is a heavily glycosylated protein on the surface of the virion as homotrimer,responsible for binding to human angiotensin-converting enzyme 2(hACE2)receptor.2 While the architecture of S trimers has been well studied,how the stability of S is regulated by potential host factors remains unknown.

Distinct and relatively mild clinical characteristics of SARS-CoV-2 BA.5 infections against BA.2

Dear Editor,The global pandemic of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)Omicron variant has resulted in its continuous evolution and the emergence of numerous subvariants of Omicron(https://gisaid.org/).Currently,possibly owing to the increased evasion of neutralizing antibodies elicited by previous infection and vaccination and the higher transmissibility,the BA.5 variant has replaced BA.2 variant and dominated the pandemic.

Preclinical characterization and anti-SARS-CoV-2 efficacy of ATV014:an oral cyclohexanecarboxylate prodrug of 1′-CN-4-aza-7,9-dideazaadenosine C-nucleoside

Dear Editor,Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),the causative agent of the global pandemic coronavirus disease 2019(COVID-19),has proven itself to be a highly virulent respiratory pathogen with an unpredictable evolutionary capacity,posing a persistent threat to mankind.At the time of this manuscript’s publication.

Suppression of UsP8 sensitizes cells to ferroptosis via SQSTM1/p62-mediated ferritinophagy

Dear Editor,Ferroptosis is a newly discovered form of regulated cell death characterized by increased intracellular iron accumulation and subsequent lipid peroxidation(Dixon et al.,2012).Studies have revealed that ferroptosis plays an important role in multiple physiological and pathological processes including degenerative diseases,carcinogenesis,and cancer immunotherapy(Hassannia et al.,2019,Wang et al.,2019).

Current status of severe fever with thrombocytopenia syndrome in China

Severe fever with thrombocytopenia syndrome （SFTS） is an emerging infectious disease caused by SFTS virus （SFTSV）. SFTSV is associated with a high mortality rate and has been reported in China, South Korea and Japan. SFTSV undergoes rapid changes owing to evolution, gene mutations, and reassortment between different strains of SFTSV. In this review, we summarize the recent cases and general properties of SFTS, focusing on the epidemiology, genetic diversity, clinical features, and diagnostics of SFTSV in China. From 2010 to October 2016, SFTS cases were reported in 23 provinces of China, with increased numbers yearly. Infection and death cases are mainly found in central China, where the Haemaphysalis Iongicornis ticks are spread. The national average mortality rate of SFTS infection was 5.3%, with higher risk to elder people. The main epidemic period was from May to July, with a peak in May. Thus, SFTS reminds a significant public health problem, and development of prophylactic vaccines and effective antiviral drugs will be highly needed.

The functions of tumor suppressor PTEN in innate and adaptive immunity

The tumor suppressor phosphatase and tensin homolog(PTEN)is a lipid and protein phosphatase that is able to antagonize the PI3K/AKT pathway and inhibit tumor growth.PTEN also possesses phosphatase-independent functions.Genetic alterations of PTEN may lead to the deregulation of cell proliferation,survival,differentiation,energy metabolism and cellular architecture and mobility.Although the role of PTEN in tumor suppression is extensively documented and well established,the evidence for its roles in immunity did not start to accumulate until recently.In this review,we will focus on the newly discovered functions of PTEN in the regulation of innate and adaptive immunity,including antiviral responses.

Autophagy receptor CCDC50 tunes the STING-mediated interferon response in viral infections and autoimmune diseases

DNA sensing and timely activation of interferon(IFN)-mediated innate immunity are crucial for the defense against DNA virus infections and the clearance of abnormal cells.However,overactivation of immune responses may lead to tissue damage and autoimmune diseases;therefore,these processes must be intricately regulated.STING is the key adaptor protein,which is activated by cyclic GMP-AMP,the second messenger derived from cGAS-mediated DNA sensing.Here,we report that CCDC50,a newly identified autophagy receptor,tunes STING-directed type I IFN signaling activity by delivering K63-polyubiquitinated STING to autolysosomes for degradation.Knockout of CCDC50 significantly increases herpes simplex virus 1(HSV-1)-or DNA ligand-induced production of type I IFN and proinflammatory cytokines.Ccdc50-deficient mice show increased production of IFN,decreased viral replication,reduced cell infiltration,and improved survival rates compared with their wild-type littermates when challenged with HSV-1.Remarkably,the expression of CCDC50 is downregulated in systemic lupus erythematosus(SLE),a chronic autoimmune disease.CCDC50 levels are negatively correlated with IFN signaling pathway activation and disease severity in human SLE patients.CCDC50 deficiency potentiates the cGAS-STING-mediated immune response triggered by SLE serum.Thus,our findings reveal the critical role of CCDC50 in the immune regulation of viral infections and autoimmune diseases and provide insights into the therapeutic implications of CCDC50 manipulation.

A Convenient and Biosafe Replicon with Accessory Genes of SARS-CoV-2 and Its Potential Application in Antiviral Drug Discovery

SARS-CoV-2 causes the pandemic of COVID-19 and no effective drugs for this disease are available thus far.Due to the high infectivity and pathogenicity of this virus,all studies on the live virus are strictly confined in the biosafety level 3(BSL3)laboratory but this would hinder the basic research and antiviral drug development of SARS-CoV-2 because the BSL3 facility is not commonly available and the work in the containment is costly and laborious.In this study,we constructed a reverse genetics system of SARS-CoV-2 by assembling the viral cDNA in a bacterial artificial chromosome(BAC)vector with deletion of the spike(S)gene.Transfection of the cDNA into cells results in the production of an RNA replicon that keeps the capability of genome or subgenome replication but is deficient in virion assembly and infection due to the absence of S protein.Therefore,such a replicon system is not infectious and can be used in ordinary biological laboratories.We confirmed the efficient replication of the replicon by demonstrating the expression of the subgenomic RNAs which have similar profiles to the wild-type virus.By mutational analysis of nsp12 and nsp14,we showed that the RNA polymerase,exonuclease,and cap N7 methyltransferase play essential roles in genome replication and sgRNA production.We also created a SARS-CoV-2 replicon carrying a luciferase reporter gene and this system was validated by the inhibition assays with known anti-SARS-CoV-2 inhibitors.Thus,such a one-plasmid system is biosafe and convenient to use,which will benefit both fundamental research and development of antiviral drugs.

PTEN-L promotes type I interferon responses and antiviral immunity

Phosphatase and tensin homolog deleted on chromosome ten(PTEN)is a well-known tumor suppressor that acts as a dual-specificity phosphatase and is frequently mutated in human cancer.Our previous work has demonstrated that PTEN also plays a vital role in type I interferon responses and antiviral innate immunity.Recently,a translational variant of PTEN with a long N-terminal extension(PTEN-L)has been discovered that is secreted into the extracellular environment and enters recipient cells,where it exerts a phosphatase function antagonistic to PI3K/Akt signaling and tumorigenesis.In this study,we demonstrate that PTEN-L promotes type I interferon responses and antiviral innate immunity during viral infection in a phosphatase activity-dependent manner.Compared with canonical PTEN,PTEN-L also exerts its antiviral function when it is applied exogenously in protein form.This finding was confirmed in cell cultures and mouse infection models.Furthermore,PTEN-L enhances the responses of both type I interferon and proinflammatory cytokines,thus suggesting that PTEN-L might possess additional functions compared with those of PTEN.Thus,the antiviral function of PTEN-L may open an avenue for the use of PTEN-L in antiviral therapy,particularly in patients with PTEN-deficient tumors.

Rapid isolation and immune profiling of SARS-CoV-2 specific memory B cell in convalescent COVID-19 patients via LIBRA-seq

B cell response plays a critical role against SARS-CoV-2 infection.However,little is known about the diversity and frequency of the paired SARS-CoV-2 antigen-specific BCR repertoire after SARS-CoV-2 infection.Here,we performed single-cell RNA sequencing and VDJ sequencing using the memory and plasma B cells isolated from five convalescent COVID-19 patients,and analyzed the spectrum and transcriptional heterogeneity of antibody immune responses.Via linking BCR to antigen specificity through sequencing(LIBRA-seq),we identified a distinct activated memory B cell subgroup(CD11c^(high) CD95^(high))had a higher proportion of SARS-CoV-2 antigen-labeled cells compared with memory B cells.Our results revealed the diversity of paired BCR repertoire and the non-stochastic pairing of SARS-CoV-2 antigen-specific immunoglobulin heavy and light chains after SARS-CoV-2 infection.The public antibody clonotypes were shared by distinct convalescent individuals.Moreover,several antibodies isolated by LIBRA-seq showed high binding affinity against SARS-CoV-2 receptor-binding domain(RBD)or nucleoprotein(NP)via ELISA assay.Two RBD-reactive antibodies C14646P3S and C2767P3S isolated by LIBRA-seq exhibited high neutralizing activities against both pseudotyped and authentic SARS-CoV-2 viruses in vitro.Our study provides fundamental insights into B cell response following SARS-CoV-2 infection at the single-cell level.

Molecular mechanisms of coronavirus RNA capping and methylation

The 5′-cap structures of eukaryotic m RNAs are important for RNA stability, pre-m RNA splicing,m RNA export, and protein translation. Many viruses have evolved mechanisms for generating their own cap structures with methylation at the N7 position of the capped guanine and the ribose 2′-Oposition of the first nucleotide, which help viral RNAs escape recognition by the host innate immune system. The RNA genomes of coronavirus were identified to have 5′-caps in the early1980 s. However, for decades the RNA capping mechanisms of coronaviruses remained unknown.Since 2003, the outbreak of severe acute respiratory syndrome coronavirus has drawn increased attention and stimulated numerous studies on the molecular virology of coronaviruses. Here, we review the current understanding of the mechanisms adopted by coronaviruses to produce the 5′-cap structure and methylation modification of viral genomic RNAs.

Mechanisms and Effects on HBV Replication of the Interaction between HBV Core Protein and Cellular Filamin B

Hepatitis B virus(HBV) infection is one of the major problems that threatens global health. There have been many studies on HBV, but the relationship between HBV and host factors is largely unexplored and more studies are needed to clarify these interactions. Filamin B is an actin-binding protein that acts as a cytoskeleton protein, and it is involved in cell development and several signaling pathways. In this study, we showed that filamin B interacted with HBV core protein,and the interaction promoted HBV replication. The interaction between filamin B and core protein was observed in HEK293T, Huh7 and HepG2 cell lines by co-immunoprecipitation and co-localization immnofluoresence. Overexpression of filamin B increased the levels of HBV total RNAs and pre-genome RNA(pg RNA), and improved the secretion level of hepatitis B surface antigen(HBsAg) and hepatitis B e antigen(HBeAg). In contrast, filamin B knockdown inhibited HBV replication, decreased the level of HBV total RNAs and pgRNA, and reduced the secretion level of HBsAg and HBeAg. In addition, we found that filamin B and core protein may interact with each other via four blocks of argentine residues at the C-terminus of core protein. In conclusion, we identify filamin B as a novel host factor that can interact with core protein to promote HBV replication in hepatocytes. Our study provides new insights into the relationship between HBV and host factors and may provide new strategies for the treatment of HBV infection.

Non-Structural Protein 5 of Zika Virus Interacts with p53 in Human Neural Progenitor Cells and Induces p53-Mediated Apoptosis

Zika virus(ZIKV) infection could disrupt neurogenesis and cause microcephaly in neonates by targeting neural progenitor cells(NPCs). The tumor suppressor p53-mediated cell cycle arrest and apoptotic cell death have been suggested to be activated upon ZIKV infection, yet the detailed mechanism is not well understood. In the present study, we investigated the effects of ZIKV-encoded proteins in the activation of p53 signaling pathway and found that, among the ten viral proteins,the nonstructural protein 5(NS5) of ZIKV most significantly activated the transcription of p53 target genes. Using the immunoprecipitation-coupled mass spectrometry approach, we identified that ZIKV-NS5 interacted with p53 protein. The NS5-p53 interaction was further confirmed by co-immunoprecipitation and GST pull-down assays. In addition, the MTase domain of NS5 and the C-terminal domain of p53 were mapped to be responsible for the interaction between these two proteins. We further showed that ZIKV-NS5 was colocalized with p53 and increased its protein level in the nuclei and able to prolong the half-life of p53. Furthermore, lentivirus-mediated expression of ZIKV-NS5 in hNPCs led to an apparent cell death phenotype. ZIKV-NS5 promoted the cleavage of PARP1 and significantly increased the cell apoptosis of h NPCs.Taken together, these findings revealed that ZIKV-NS5 is a previously undiscovered regulator of p53-mediated apoptosis in hNPCs, which may contribute to the ZIKV-caused abnormal neurodevelopment.

PTEN suppresses tumorigenesis by directly dephosphorylating Akt

Dear Editor,The serine-threonine kinase Akt plays a central role in regulating cell proliferation,migration,angiogenesis,transformation,energy metabolism,and death.1 The stimulation of growth factors recruits the PI3K to the plasma membrane and phosphatidylinositol-3A5-trisphosphate(PIP3),which in turn recruits Akt to the plasma membrane through PH domain of Akt.

Severe acute respiratory syndrome coronavirus protein 6 mediates ubiquitin-dependent proteosomal degradation of N-Myc(and STAT) interactor

Severe acute respiratory syndrome coronavirus(SARS-Co V) encodes eight accessory proteins, the functions of which are not yet fully understood. SARS-Co V protein 6(P6) is one of the previously studied accessory proteins that have been documented to enhance viral replication and suppress host interferon(IFN) signaling pathways. Through yeast two-hybrid screening, we identified eight potential cellular P6-interacting proteins from a human spleen c DNA library. For further investigation, we targeted the IFN signaling pathway-mediating protein, N-Myc(and STAT) interactor(Nmi). Its interaction with P6 was confirmed within cells. The results showed that P6 can promote the ubiquitin-dependent proteosomal degradation of Nmi. This study revealed a new mechanism of SARS-Co V P6 in limiting the IFN signaling to promote SARS-Co V survival in host cells.

Coronavirus: epidemiology, genome replication and the interactions with their hosts

This special issue of the journal is dedicated to the recent progress on coronaviruses and covers the topics of viral epidemiology,virus replication and the interactions between the coronaviruses and their hosts.Members of the family Coronaviridae infect a wide range of vertebrates and humans.

Old Weapon for New Enemy:Drug Repurposing for Treatment of Newly Emerging Viral Diseases

Emerging and re-emerging viral diseases are a public health concern for the whole world and pose a major threat to human health and life.In last decades,numerous major outbreaks of emerging and re-emerging viral diseases with gross public concern were recorded in different regions,including Ebola in western Africa,Zika in South America.

A novel strategy to generate virus vaccines with expanded genetic codes

The invention and application of vaccines for combating infectious diseases represent one of the greatest human accomplishments within the medical and health sectors in the history of mankind.The smallpox virus,once devastating and widespread across the continents,is the first and sole human pathogen that has been eradicated globally,and this great success is attributed to the use of vaccinia vaccines.

Suppression of HIV-1 Integration by Targeting HIV-1 Integrase for Degradation with A Chimeric Ubiquitin Ligase

Human immunodeficiency virus(HIV) attacks human immune system and causes life-threatening acquired immune deficiency syndrome(AIDS). Treatment with combination antiretroviral therapy(cART) could inhibit virus growth and slow progression of the disease, however, at the same time posing various adverse effects. Host ubiquitin-proteasome pathway(UPP) plays important roles in host immunity against pathogens including viruses by inducing degradation of viral proteins. Previously a series of methods for retargeting substrates for ubiquitin-proteasome degradation have been successfully established. In this study, we attempted to design and construct artificial chimeric ubiquitin ligases(E3 s) based on known human E3 s in order to manually target HIV-1 integrase for ubiquitin proteasome pathway-mediated degradation.Herein, a series of prototypical chimeric E3 s have been designed and constructed, and original substrate-binding domains of these E3 s were replaced with host protein domains which interacted with viral proteins. After functional assessment screening, 146 LI was identified as a functional chimeric E3 for HIV-1 NL4-3 integrase. 146 LI was then further optimized to generate 146 LIS(146 LI short) which has been shown to induce Lys48-specific polyubiquitination and reduce protein level of HIV-1 NL4-3 integrase more effectively in cells. Lymphocyte cells with 146 LIS knock-in generated by CRISPR/Cas-mediated homology-directed repair(HDR) showed remarkably decreased integration of HIV-1 NL4-3 viral DNAs and reduced viral replication without obvious cell cytotoxicity. Our study successfully obtained an artificial chimeric E3 which can induce Lys48-specific polyubiquitination and proteasome-mediated degradation of HIV-1 NL4-3 integrase, thus effectively inhibiting viral DNA integration and viral replication upon virus infection.