Considering that HBV belongs to the DNA virus family and is hepatotropic,we model the HBV DNA-containing capsids as a compartment.In this paper,a delayed HBV infection model is established,where the general incidence ...Considering that HBV belongs to the DNA virus family and is hepatotropic,we model the HBV DNA-containing capsids as a compartment.In this paper,a delayed HBV infection model is established,where the general incidence function and two infection routes including cell-virus infection and cell-cell infection are introduced.According to some preliminaries,including well-posedness,basic reproduction number and existence of two equilibria,we obtain the threshold dynamics for the model.We illustrate numerical simulations to verify the above theoretical results,and furthermore explore the impacts of intracellular delay and cell-cell infection on the global dynamics of the model.展开更多
Oral antiretroviral drugs have been a fundamental component of human immunodeficiency virus(HIV)treatment for over three decades,and their continuously improving safety and efficacy have directly contributed to revers...Oral antiretroviral drugs have been a fundamental component of human immunodeficiency virus(HIV)treatment for over three decades,and their continuously improving safety and efficacy have directly contributed to reversing the initially devastating course of the HIV epidemic.Long-acting antiretroviral(ARV)regimens are necessary to sustain viral suppression in people living with HIV who express a strong desire to alleviate pill fatigue or avoid the potential stigma associated with daily oral regimens.The development of innovative long-acting ARVs remains an unmet requirement in the fields of HIV treatment and prevention.In this review,we provide an overview of lenacapavir,a first-in-class picomolar long-acting capsid inhibitor for HIV-1 that operates through multiple stages without any known cross-resistance to other existing antiretroviral drug classes.展开更多
Porcine circovirus type 3(PCV3)was initially identified in 2016 in pigs exhibiting unexplained cardiac and multi-organ inflammation in the USA(Palinski et al.2017).PCV3 has subsequently been identified in numerous cou...Porcine circovirus type 3(PCV3)was initially identified in 2016 in pigs exhibiting unexplained cardiac and multi-organ inflammation in the USA(Palinski et al.2017).PCV3 has subsequently been identified in numerous countries,including China,Brazil,Italy,and others,demonstrating widespread viral dissemination(Tan et al.2021).Notably,recent investigations have revealed PCV3 infection across multiple species,including pigs,cattle,dogs,wild boars,chamois,roe deer,and others(Tan et al.2021).This evidence suggests potential viral propagation beyond its primary host(pigs).展开更多
Mass mortality of mandarin fish(Siniperca chuatsi)due to infectious spleen and kidney necrosis virus(ISKNV)infection occurs frequently.Since there are no effective drug treatments available,prevention relies heavily o...Mass mortality of mandarin fish(Siniperca chuatsi)due to infectious spleen and kidney necrosis virus(ISKNV)infection occurs frequently.Since there are no effective drug treatments available,prevention relies heavily on detection.Effective and rapid on-site detection methods are needed for early diagnosis of ISKNV.In this study,a rapid and simple colloidal gold test strip method,specific for the antibody against major capsid protein(MCP),was developed and systematically evaluated for the detection of ISKNV.The limit of detection of the test strip is a 1꞉100 dilution of a positive standard serum and the antibody level in the fish could be estimated from the depth of color of the test line.The strips were tested against serum samples of cyprinid herpesvirus-2(CyHV-2),grass carp reovirus(GCRV),largemouth bass ranavirus(LMBV),large yellow croaker iridovirus(LYCIV),and spring viremia of carp virus(SVCV),yielding no cross-reactivity.In addition,10 mandarin fish artificially infected with ISKNV were tested using the current industry standard PCR method(SC/T 7211-2011)on their splenorenal tissues.The results from the test strips showed a high degree of concordance with PCR testing,achieving a Kappa value of 0.737.All the results indicated that the colloidal gold test strips prepared in this study could be used as a simple,rapid,and highly sensitive and specific method for ISKNV diagnosis.展开更多
Foot-and-mouth disease is a highly contagious disease that produces severe economic losses in the livestock industry. This disease is being controlled by the use of an inactivated vaccine. However, the use of recombin...Foot-and-mouth disease is a highly contagious disease that produces severe economic losses in the livestock industry. This disease is being controlled by the use of an inactivated vaccine. However, the use of recombinant empty capsids as a subunit vaccine has been reported to be a promising candidate because it avoids the use of virus in the vaccine production. A plasmid containing the capsid precursor P12A and protease 3C sequences of foot-and-mouth disease virus (FMDV) was constructed and used to compare transient and stable expression in mammalian cells. When BHK-21 cells were transfected with the recombinant vector, protease 3C cleaved the capsid precursor P12A into the structural proteins VP0, VP1 and VP3. A sucrose gradient demonstrated that the structural proteins assembled into different subviral particles. Attempts to generate a stable cell line only allowed isolating low-level-expressing clones, probably due to the effect of protease 3C on the cells. Moreover, the recombinant protein yield achieved in transient expression assays was much higher than the one achieved in stable expression assays. Results indicate that mammalian cells are a good strategy to produce recombinant FMDV subviral particles. However, the alternative approach of transient gene expression in scalable systems should be used instead of the standard method that involves the generation of a stable cell line.展开更多
The hepatitis B virus （HBV） particle consists of an envelope containing three related surface proteins and probably lipid and an icosahedral nucleocapsid of approximately 30 nm diameter enclosing the viral DNA genom...The hepatitis B virus （HBV） particle consists of an envelope containing three related surface proteins and probably lipid and an icosahedral nucleocapsid of approximately 30 nm diameter enclosing the viral DNA genome and DNA polymerase. The capsid is formed in the cytosol of the infected cell during packaging of an RNA pregenome replication complex by multiple copies of a 21-kDa C protein. The capsid gains the ability to bud during synthesis of the viral DNA genome by reverse transcription of the pregenome in the lumen of the particle. The three envelope proteins S, t4, and L shape a complex transmembrane fold at the endoplasmic reticulum, and form disulfide-linked homoand heterodimers. The transmembrane topology of a fraction of the large envelope protein L changes posttranslationally, therefore, the N terminal domain of L （preS） finally appears on both sides of the membrane. During budding at an intracellular membrane, a short linear domain in the cytosolic preS region interacts with binding sites on the capsid surface. The virions are subsequently secreted into the blood. In addition, the surface proteins can bud in the absence of capsids and form subviral lipoprotein particles of 20 nm diameter which are also secreted.展开更多
For genome mulUplication hepadnaviruses use the transcriptional machinery of the cell that is found within the nucleus. Thus the viral genome has to be transported through the cytoplasm and nuclear pore. The intracyto...For genome mulUplication hepadnaviruses use the transcriptional machinery of the cell that is found within the nucleus. Thus the viral genome has to be transported through the cytoplasm and nuclear pore. The intracytosolic translocation is facilitated by the viral capsid that surrounds the genome and that interacts with cellular microtubules. The subsequent passage through the nuclear pore complexes （NPC） is mediated by the nuclear transport receptors importin α andβ. Importin α binds to the C-terminus of the capsid protein that comprises a nuclear localization signal （NLS）. The exposure of the NLS is regulated and depends upon genome maturation and/or phosphorylation of the capsid protein. As for other karyophilic cargos using this pathway importin α interacts with importin β that facilitates docking of the import complex to the NPC and the passage through the pore. Being a unique strategy, the import of the viral capsid is incomplete in that it becomes arrested inside the nuclear basket, which is a cage-like structure on the karyoplasmic face of the NPC. Presumably only this compartment provides the factors that are required for capsid disassembly and genome release that is restricted to those capsids comprising a mature viral DNA genome.展开更多
Dear Editor,Zika virus (ZIKV) is a mosquito-borne virus that belongs to the Flavivirus family along with dengue virus (DENV),yellow fever virus, West Nile virus, and Japanese encephalitis virus (Ming et al. 2016). ZIK...Dear Editor,Zika virus (ZIKV) is a mosquito-borne virus that belongs to the Flavivirus family along with dengue virus (DENV),yellow fever virus, West Nile virus, and Japanese encephalitis virus (Ming et al. 2016). ZIKV is a singlestranded positive-sense RNA virus encoding three structural proteins, including nucleocapsid protein C, prM/M,envelope glycoprotein E, and seven non-structural proteins.Since 2015.展开更多
Porcine circovirus type 2（PCV2）has recently been reported to elicit the unfolded protein response（UPR）via activation of the PERK/e IF2α（RNA-activated protein kinase-like endoplasmic reticulum（ER）kinase/eukaryo...Porcine circovirus type 2（PCV2）has recently been reported to elicit the unfolded protein response（UPR）via activation of the PERK/e IF2α（RNA-activated protein kinase-like endoplasmic reticulum（ER）kinase/eukaryotic initiation factor 2α）pathway.This study attempted to examine which viral protein might be involved in inducing UPR and whether this cellular event would lead to apoptosis of the cells expressing the viral protein.By transient expression,we found that both replicase（Rep）and capsid（Cap）proteins of PCV2 could induce ER stress as shown by increased phosphorylation of PERK with subsequent activation of the eI F2α-ATF4（activating transcription factor 4）-CHOP（CCAAT/enhancer-binding protein homologous protein）axis.Cap expression,but not Rep,significantly reduced antiapoptotic B-cell lymphoma-2（Bcl-2）and increased caspase-3 cleavage,possibly due to increased expression of CHOP.Since knockdown of PERK by RNA interference clearly reduced Cap-induced CHOP expression,caspase-3cleavage,and apoptotic cell death possibly by partially rescuing Bcl-2 expression,we propose that there is connection between Cap-induced UPR and apoptosis via the PERK/eI F2α/ATF4/CHOP/Bcl-2 pathway.This study,together with our earlier studies,provides insight into the mechanisms underlying PCV2 pathogenesis.展开更多
Porcine circovirus 3(PCV3)has been detected in major pig-producing countries around the world since its first report in the US in 2016.Most current studies have focused on epidemiological investigations and detection ...Porcine circovirus 3(PCV3)has been detected in major pig-producing countries around the world since its first report in the US in 2016.Most current studies have focused on epidemiological investigations and detection methods of PCV3 because of lack of live virus strains for research on its pathogenesis in porcine cells or even in pigs.We constructed a recombinant plasmid pCMV-Cap carrying the PCV3 orf2 gene to investigate the effects of capsid(Cap)protein expression on autophagic response in human embryonic kidney cell line 293 T(HEK293 T).We demonstrate that PCV3 Cap protein induced complete autophagy shown as formation of autophagosomes and autophagosome-like vesicles as well as LC3-II conversion from LC3-I via inhibiting phosphorylation of the mammalian target of rapamycin(mTOR)in HEK293 T cells.The ubiquitin–proteasome pathway is also involved in the autophagy process.These findings provide insight for further exploration of PCV3 pathogenetic mechanisms in porcine cells.展开更多
Despite the improving coverage of preventative vaccines,hepatitis B remains a severe global public health problem,with more than 250 million patients living with hepatitis B virus(HBV)infection.Current available thera...Despite the improving coverage of preventative vaccines,hepatitis B remains a severe global public health problem,with more than 250 million patients living with hepatitis B virus(HBV)infection.Current available therapies,including nucleos(t)ide analogs and peginterferon,can control HBV replication but fail to eliminate covalently closed circular DNA(cccDNA)and achieve a cure.The HBV core protein(Cp)is a well-conserved structural protein,self-assembling to form the viral capsid.It involves in or modulates almost every stage of the HBV lifecycle,which makes it an attractive target for the development of new anti-HBV therapies.HBV core protein allosteric modulators(CpAMs)have become a hotspot in recent years.Herein,we provide a concise report focusing on the various medicinal chemistry strategies involved in the latest research(2018-2022)of HBV CpAMs,including high throughput screening(HTS),virtual screening(VS),drug repositioning,natural products,substitution decorating approach,scaffold hopping,molecular hybridization,prodrug strategy and conformational constraint strategy,to provide guidance for further development of new and effective anti-HBV drugs.展开更多
Three pairs of specific primers were designed to amplify the F2-1, F2-2 and XF2-2 truncated sequences of ORF2 which encodes the capsid protein of porcine circovirus type 2 （PCV-2）. The F2-1 sequence had most of the ...Three pairs of specific primers were designed to amplify the F2-1, F2-2 and XF2-2 truncated sequences of ORF2 which encodes the capsid protein of porcine circovirus type 2 （PCV-2）. The F2-1 sequence had most of the NLS region of ORF2, but the F2-2 and XF2-2 genes had the NLS region deleted. Truncated genes were subcloned into pET-32a（＋） vectors to construct recombinant fusion expression vectors. The vectors were then transformed into Rosetta（DE3） E. coli and expressed by induction of IPTG. Expressed proteins were detected by western blotting and ELISA. The protein with best immunoreactivity was confirmed and selected, then utilized to inoculate SPF rabbits to prepare polyclonal antibodies. The protein and prepared polyclonal antibody were utilized to detect sera samples against PCV-2 from Shandong province and PCV-2 particles in PK-15 cells. In our study, three recombinant fusion proteins were successfully obtained, and the molecular weights of fusion proteins were 35.9 kDa, 33.6 kDa and 38.6 kDa respectively detected by SDS-PAGE. All of the proteins showed positive reaction with anti-PCV-2 antisera, and His-XF2-2 showed better immunoreactivity than the others. The protein of His-XF2-2 was coated as antigen in ELISA to detect the seroprevalence of PCV-2 in certain districts of Shandong province, the seropositivity rate was 27.7 % （73/264）. Specific fluorescence and positive signals for PCV-2 could be detected in PK-15 cells inoculated with PCV-2 with the participation of prepared antibodies against His-XF2-2 in IFA and IPMA. Experimental results indicated that the truncated PCV-20RF2 gene containing most of the NLS region was successfully expressed in E. coli, and His-XF2-2 was demonstrated to have better immunoreactivity with anti-PCV-2 antisera than the other two fusion proteins. His-XF2-2 and prepared polyclonal antibodies against it had a satisfactory capability in detecting PCV-2 infection.展开更多
The family Picornaviridae is one of the largest families of human viral pathogens,causing an extensive range of clinical manifestations from mild fever,common cold to serious paralytic poliomyelitis,COPD,etc.,some of ...The family Picornaviridae is one of the largest families of human viral pathogens,causing an extensive range of clinical manifestations from mild fever,common cold to serious paralytic poliomyelitis,COPD,etc.,some of which can even be life-threatening.Picornaviruses also cause zoonotic epidemics that result in dramatic social and economical losses.Although no efficient antivirus agent for prophylaxis or treatment of picornarivus infections has been officially approved yet,a large number of anti-picornavirus compounds with potent activity have been developed and investigated,through which further information about picornavirus has been revealed as well.Viral mRNA translation,viral mRNA replication and especially the viral capsid are the three main targets of these compounds having been extensively studied.The typical one is the WIN series of compounds that bind to the viral capsid and inhibit rival attachment or uncoating.Herein,a perspective on picornavirus inhibitors and a concrete evolution of WIN compounds will be presented in this paper.展开更多
Grass carp reovirus (GCRV) is a tentative member of the Aquareovirus genus in the family Reoviridae. The mature virion comprises 11 dsRNA genomes enclosed by two concentric icosahedral proteins shells that is comprise...Grass carp reovirus (GCRV) is a tentative member of the Aquareovirus genus in the family Reoviridae. The mature virion comprises 11 dsRNA genomes enclosed by two concentric icosahedral proteins shells that is comprised of five core proteins and two outer capsid proteins. The genome sequence and 3D structure demonstrate there is a higher level of sequence homology in structural proteins between GCRV and mammalian orthoreoviruses (MRV) compared to other members of the family. To understand the pathogenesis of GCRV infection, the outer capsid protein VP5, a homology of the μ1 protein of MRV, was expressed in E.coli. It was found that the recombinant VP5 was highly expressed, and the expressed His-tag fusion protein was involved in the formation of the inclusion body. Additionally, specific anti-VP5 serum was prepared from purified protein and western blot demonstrated that the expressed protein was able to bind immunologically to rabbit anti GCRV particle serum and the immunogenicity was determined by ELISA assay. Additional experiments in investigating the functional properties of VP5 will further elucidate the role of the GCRV outer capsid protein VP5 during entry into host cells, and its interaction among viral proteins and host cells during the infection process.展开更多
VP1, a capsid protein of swine vesicular disease virus, was cloned from the SVDV HK/70 strain and inserted into retroviral vector pBABE puro, and expressed in PK15 cells by an retroviral expression system. The ability...VP1, a capsid protein of swine vesicular disease virus, was cloned from the SVDV HK/70 strain and inserted into retroviral vector pBABE puro, and expressed in PK15 cells by an retroviral expression system. The ability of the VP1 protein to induce an immune response was then evaluated in guinea pigs. Western blot and ELISA results indicated that the VP1 protein can be recognized by SVDV positive serum, Furthermore, anti-SVDV specific antibodies and lymphocyte proliferation were elicited and increased by VP1 protein after vaccination. These results encourage further work towards the development of a vaccine against SVDV infection.展开更多
This study bioinformatically analyzed the non-VP1 capsid proteins（VP2-VP4） of Coxasckievirus A6（CVA6）, with an attempt to predict their basic physicochemical properties, structural/functional features and linear B...This study bioinformatically analyzed the non-VP1 capsid proteins（VP2-VP4） of Coxasckievirus A6（CVA6）, with an attempt to predict their basic physicochemical properties, structural/functional features and linear B cell eiptopes. The online tools Sub Loc, Target P and the others from Ex PASy Bioinformatics Resource Portal, and SWISS-MODEL（an online protein structure modeling server）, were utilized to analyze the amino acid（AA） sequences of VP2-VP4 proteins of CVA6. Our results showed that the VP proteins of CVA6 were all of hydrophilic nature, contained phosphorylation and glycosylation sites and harbored no signal peptide sequences and acetylation sites. Except VP3, the other proteins did not have transmembrane helix structure and nuclear localization signal sequences. Random coils were the major conformation of the secondary structure of the capsid proteins. Analysis of the linear B cell epitopes by employing Bepipred showed that the average antigenic indices（AI） of individual VP proteins were all greater than 0 and the average AI of VP4 was substantially higher than that of VP2 and VP3. The VP proteins all contained a number of potential B cell epitopes and some eiptopes were located at the internal side of the viral capsid or were buried. We successfully predicted the fundamental physicochemical properties, structural/functional features and the linear B cell eiptopes and found that different VP proteins share some common features and each has its unique attributes. These findings will help us understand the pathogenicity of CVA6 and develop related vaccines and immunodiagnostic reagents.展开更多
基金Supported by the Natural Science Foundation of Shanxi Province(202303021211003)the National Natural Science Foundation of China(12126349,11601293,12361102)the Scientific Plan of Guizhou Province(No.Qian Ke He Jichu-ZK[2021]YiBan002).
文摘Considering that HBV belongs to the DNA virus family and is hepatotropic,we model the HBV DNA-containing capsids as a compartment.In this paper,a delayed HBV infection model is established,where the general incidence function and two infection routes including cell-virus infection and cell-cell infection are introduced.According to some preliminaries,including well-posedness,basic reproduction number and existence of two equilibria,we obtain the threshold dynamics for the model.We illustrate numerical simulations to verify the above theoretical results,and furthermore explore the impacts of intracellular delay and cell-cell infection on the global dynamics of the model.
基金supported by National Key R&D Program of China(No.2023YFC2306800)Natural Science Foundation of Shandong Province(No.ZR2024QH201)+4 种基金the Postdoctoral Fellowship Program of CPSF(No.GZC20231489)China Postdoctoral Science Foundation(No.2023M742101)the Key Research and Development Program,Ministry of Science and Technology of the People’s Republic of China(No.2023YFC2606500)the Shandong Laboratory Program(No.SYS202205)Sanming Project of Medicine in Shenzhen(No.SZSM202311032).
文摘Oral antiretroviral drugs have been a fundamental component of human immunodeficiency virus(HIV)treatment for over three decades,and their continuously improving safety and efficacy have directly contributed to reversing the initially devastating course of the HIV epidemic.Long-acting antiretroviral(ARV)regimens are necessary to sustain viral suppression in people living with HIV who express a strong desire to alleviate pill fatigue or avoid the potential stigma associated with daily oral regimens.The development of innovative long-acting ARVs remains an unmet requirement in the fields of HIV treatment and prevention.In this review,we provide an overview of lenacapavir,a first-in-class picomolar long-acting capsid inhibitor for HIV-1 that operates through multiple stages without any known cross-resistance to other existing antiretroviral drug classes.
基金supported by the National Key Research and Development Program of China (2023YFD1800500)the Jiangsu Innovative and Entrepreneurial Talent Team Project,China (JSSCTD202224)+1 种基金the 111 Project D18007the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD),China
文摘Porcine circovirus type 3(PCV3)was initially identified in 2016 in pigs exhibiting unexplained cardiac and multi-organ inflammation in the USA(Palinski et al.2017).PCV3 has subsequently been identified in numerous countries,including China,Brazil,Italy,and others,demonstrating widespread viral dissemination(Tan et al.2021).Notably,recent investigations have revealed PCV3 infection across multiple species,including pigs,cattle,dogs,wild boars,chamois,roe deer,and others(Tan et al.2021).This evidence suggests potential viral propagation beyond its primary host(pigs).
基金Supported by the Earmarked Fund for China Agricultural Research System(No.CARS-45-16)the Key Research and Development Plan of Jiangsu Province(No.BE2021369)。
文摘Mass mortality of mandarin fish(Siniperca chuatsi)due to infectious spleen and kidney necrosis virus(ISKNV)infection occurs frequently.Since there are no effective drug treatments available,prevention relies heavily on detection.Effective and rapid on-site detection methods are needed for early diagnosis of ISKNV.In this study,a rapid and simple colloidal gold test strip method,specific for the antibody against major capsid protein(MCP),was developed and systematically evaluated for the detection of ISKNV.The limit of detection of the test strip is a 1꞉100 dilution of a positive standard serum and the antibody level in the fish could be estimated from the depth of color of the test line.The strips were tested against serum samples of cyprinid herpesvirus-2(CyHV-2),grass carp reovirus(GCRV),largemouth bass ranavirus(LMBV),large yellow croaker iridovirus(LYCIV),and spring viremia of carp virus(SVCV),yielding no cross-reactivity.In addition,10 mandarin fish artificially infected with ISKNV were tested using the current industry standard PCR method(SC/T 7211-2011)on their splenorenal tissues.The results from the test strips showed a high degree of concordance with PCR testing,achieving a Kappa value of 0.737.All the results indicated that the colloidal gold test strips prepared in this study could be used as a simple,rapid,and highly sensitive and specific method for ISKNV diagnosis.
文摘Foot-and-mouth disease is a highly contagious disease that produces severe economic losses in the livestock industry. This disease is being controlled by the use of an inactivated vaccine. However, the use of recombinant empty capsids as a subunit vaccine has been reported to be a promising candidate because it avoids the use of virus in the vaccine production. A plasmid containing the capsid precursor P12A and protease 3C sequences of foot-and-mouth disease virus (FMDV) was constructed and used to compare transient and stable expression in mammalian cells. When BHK-21 cells were transfected with the recombinant vector, protease 3C cleaved the capsid precursor P12A into the structural proteins VP0, VP1 and VP3. A sucrose gradient demonstrated that the structural proteins assembled into different subviral particles. Attempts to generate a stable cell line only allowed isolating low-level-expressing clones, probably due to the effect of protease 3C on the cells. Moreover, the recombinant protein yield achieved in transient expression assays was much higher than the one achieved in stable expression assays. Results indicate that mammalian cells are a good strategy to produce recombinant FMDV subviral particles. However, the alternative approach of transient gene expression in scalable systems should be used instead of the standard method that involves the generation of a stable cell line.
文摘The hepatitis B virus （HBV） particle consists of an envelope containing three related surface proteins and probably lipid and an icosahedral nucleocapsid of approximately 30 nm diameter enclosing the viral DNA genome and DNA polymerase. The capsid is formed in the cytosol of the infected cell during packaging of an RNA pregenome replication complex by multiple copies of a 21-kDa C protein. The capsid gains the ability to bud during synthesis of the viral DNA genome by reverse transcription of the pregenome in the lumen of the particle. The three envelope proteins S, t4, and L shape a complex transmembrane fold at the endoplasmic reticulum, and form disulfide-linked homoand heterodimers. The transmembrane topology of a fraction of the large envelope protein L changes posttranslationally, therefore, the N terminal domain of L （preS） finally appears on both sides of the membrane. During budding at an intracellular membrane, a short linear domain in the cytosolic preS region interacts with binding sites on the capsid surface. The virions are subsequently secreted into the blood. In addition, the surface proteins can bud in the absence of capsids and form subviral lipoprotein particles of 20 nm diameter which are also secreted.
文摘For genome mulUplication hepadnaviruses use the transcriptional machinery of the cell that is found within the nucleus. Thus the viral genome has to be transported through the cytoplasm and nuclear pore. The intracytosolic translocation is facilitated by the viral capsid that surrounds the genome and that interacts with cellular microtubules. The subsequent passage through the nuclear pore complexes （NPC） is mediated by the nuclear transport receptors importin α andβ. Importin α binds to the C-terminus of the capsid protein that comprises a nuclear localization signal （NLS）. The exposure of the NLS is regulated and depends upon genome maturation and/or phosphorylation of the capsid protein. As for other karyophilic cargos using this pathway importin α interacts with importin β that facilitates docking of the import complex to the NPC and the passage through the pore. Being a unique strategy, the import of the viral capsid is incomplete in that it becomes arrested inside the nuclear basket, which is a cage-like structure on the karyoplasmic face of the NPC. Presumably only this compartment provides the factors that are required for capsid disassembly and genome release that is restricted to those capsids comprising a mature viral DNA genome.
基金supported by the National Natural Science Foundation of China (31470848, 31470880, 31670898, and 31870867)Open Research Fund Program of the State Key Laboratory of Virology of China (2017IOV003)Jiangsu Provincial Innovative Research Team
文摘Dear Editor,Zika virus (ZIKV) is a mosquito-borne virus that belongs to the Flavivirus family along with dengue virus (DENV),yellow fever virus, West Nile virus, and Japanese encephalitis virus (Ming et al. 2016). ZIKV is a singlestranded positive-sense RNA virus encoding three structural proteins, including nucleocapsid protein C, prM/M,envelope glycoprotein E, and seven non-structural proteins.Since 2015.
基金supported by the National Natural Science Foundation of China(No.31272534)the Department of Education of Zhejiang Province(No.Y201635576),China
文摘Porcine circovirus type 2（PCV2）has recently been reported to elicit the unfolded protein response（UPR）via activation of the PERK/e IF2α（RNA-activated protein kinase-like endoplasmic reticulum（ER）kinase/eukaryotic initiation factor 2α）pathway.This study attempted to examine which viral protein might be involved in inducing UPR and whether this cellular event would lead to apoptosis of the cells expressing the viral protein.By transient expression,we found that both replicase（Rep）and capsid（Cap）proteins of PCV2 could induce ER stress as shown by increased phosphorylation of PERK with subsequent activation of the eI F2α-ATF4（activating transcription factor 4）-CHOP（CCAAT/enhancer-binding protein homologous protein）axis.Cap expression,but not Rep,significantly reduced antiapoptotic B-cell lymphoma-2（Bcl-2）and increased caspase-3 cleavage,possibly due to increased expression of CHOP.Since knockdown of PERK by RNA interference clearly reduced Cap-induced CHOP expression,caspase-3cleavage,and apoptotic cell death possibly by partially rescuing Bcl-2 expression,we propose that there is connection between Cap-induced UPR and apoptosis via the PERK/eI F2α/ATF4/CHOP/Bcl-2 pathway.This study,together with our earlier studies,provides insight into the mechanisms underlying PCV2 pathogenesis.
基金Project supported by the Zhejiang Provincial Department of Science and Technology(No.2018C02028),China。
文摘Porcine circovirus 3(PCV3)has been detected in major pig-producing countries around the world since its first report in the US in 2016.Most current studies have focused on epidemiological investigations and detection methods of PCV3 because of lack of live virus strains for research on its pathogenesis in porcine cells or even in pigs.We constructed a recombinant plasmid pCMV-Cap carrying the PCV3 orf2 gene to investigate the effects of capsid(Cap)protein expression on autophagic response in human embryonic kidney cell line 293 T(HEK293 T).We demonstrate that PCV3 Cap protein induced complete autophagy shown as formation of autophagosomes and autophagosome-like vesicles as well as LC3-II conversion from LC3-I via inhibiting phosphorylation of the mammalian target of rapamycin(mTOR)in HEK293 T cells.The ubiquitin–proteasome pathway is also involved in the autophagy process.These findings provide insight for further exploration of PCV3 pathogenetic mechanisms in porcine cells.
基金financial support from the National Natural Science Foundation of China(NSFC Nos.82173677,82211530493)the Science Foundation for Outstanding Young Scholars of Shandong Province(No.ZR2020JQ31).
文摘Despite the improving coverage of preventative vaccines,hepatitis B remains a severe global public health problem,with more than 250 million patients living with hepatitis B virus(HBV)infection.Current available therapies,including nucleos(t)ide analogs and peginterferon,can control HBV replication but fail to eliminate covalently closed circular DNA(cccDNA)and achieve a cure.The HBV core protein(Cp)is a well-conserved structural protein,self-assembling to form the viral capsid.It involves in or modulates almost every stage of the HBV lifecycle,which makes it an attractive target for the development of new anti-HBV therapies.HBV core protein allosteric modulators(CpAMs)have become a hotspot in recent years.Herein,we provide a concise report focusing on the various medicinal chemistry strategies involved in the latest research(2018-2022)of HBV CpAMs,including high throughput screening(HTS),virtual screening(VS),drug repositioning,natural products,substitution decorating approach,scaffold hopping,molecular hybridization,prodrug strategy and conformational constraint strategy,to provide guidance for further development of new and effective anti-HBV drugs.
基金supported by the special studies for social welfare researches in institutes (2005DIB4J041)
文摘Three pairs of specific primers were designed to amplify the F2-1, F2-2 and XF2-2 truncated sequences of ORF2 which encodes the capsid protein of porcine circovirus type 2 （PCV-2）. The F2-1 sequence had most of the NLS region of ORF2, but the F2-2 and XF2-2 genes had the NLS region deleted. Truncated genes were subcloned into pET-32a（＋） vectors to construct recombinant fusion expression vectors. The vectors were then transformed into Rosetta（DE3） E. coli and expressed by induction of IPTG. Expressed proteins were detected by western blotting and ELISA. The protein with best immunoreactivity was confirmed and selected, then utilized to inoculate SPF rabbits to prepare polyclonal antibodies. The protein and prepared polyclonal antibody were utilized to detect sera samples against PCV-2 from Shandong province and PCV-2 particles in PK-15 cells. In our study, three recombinant fusion proteins were successfully obtained, and the molecular weights of fusion proteins were 35.9 kDa, 33.6 kDa and 38.6 kDa respectively detected by SDS-PAGE. All of the proteins showed positive reaction with anti-PCV-2 antisera, and His-XF2-2 showed better immunoreactivity than the others. The protein of His-XF2-2 was coated as antigen in ELISA to detect the seroprevalence of PCV-2 in certain districts of Shandong province, the seropositivity rate was 27.7 % （73/264）. Specific fluorescence and positive signals for PCV-2 could be detected in PK-15 cells inoculated with PCV-2 with the participation of prepared antibodies against His-XF2-2 in IFA and IPMA. Experimental results indicated that the truncated PCV-20RF2 gene containing most of the NLS region was successfully expressed in E. coli, and His-XF2-2 was demonstrated to have better immunoreactivity with anti-PCV-2 antisera than the other two fusion proteins. His-XF2-2 and prepared polyclonal antibodies against it had a satisfactory capability in detecting PCV-2 infection.
基金National Basic Research Program of China (973Program,Grant No. 2009CB825300)National Science Foundation ofChina (Grant No. 21172006)
文摘The family Picornaviridae is one of the largest families of human viral pathogens,causing an extensive range of clinical manifestations from mild fever,common cold to serious paralytic poliomyelitis,COPD,etc.,some of which can even be life-threatening.Picornaviruses also cause zoonotic epidemics that result in dramatic social and economical losses.Although no efficient antivirus agent for prophylaxis or treatment of picornarivus infections has been officially approved yet,a large number of anti-picornavirus compounds with potent activity have been developed and investigated,through which further information about picornavirus has been revealed as well.Viral mRNA translation,viral mRNA replication and especially the viral capsid are the three main targets of these compounds having been extensively studied.The typical one is the WIN series of compounds that bind to the viral capsid and inhibit rival attachment or uncoating.Herein,a perspective on picornavirus inhibitors and a concrete evolution of WIN compounds will be presented in this paper.
基金National Basic Research Program ofChina (973 Program) (2009CB118701)National NaturalScientific Foundation of China (30671615, 30871940)+1 种基金Innovation Project of the Chinese Academy of Sciences(KSCX2-YW-N-021)Science and Technology Foundation of Zhejiang Province (2007C22052)
文摘Grass carp reovirus (GCRV) is a tentative member of the Aquareovirus genus in the family Reoviridae. The mature virion comprises 11 dsRNA genomes enclosed by two concentric icosahedral proteins shells that is comprised of five core proteins and two outer capsid proteins. The genome sequence and 3D structure demonstrate there is a higher level of sequence homology in structural proteins between GCRV and mammalian orthoreoviruses (MRV) compared to other members of the family. To understand the pathogenesis of GCRV infection, the outer capsid protein VP5, a homology of the μ1 protein of MRV, was expressed in E.coli. It was found that the recombinant VP5 was highly expressed, and the expressed His-tag fusion protein was involved in the formation of the inclusion body. Additionally, specific anti-VP5 serum was prepared from purified protein and western blot demonstrated that the expressed protein was able to bind immunologically to rabbit anti GCRV particle serum and the immunogenicity was determined by ELISA assay. Additional experiments in investigating the functional properties of VP5 will further elucidate the role of the GCRV outer capsid protein VP5 during entry into host cells, and its interaction among viral proteins and host cells during the infection process.
文摘VP1, a capsid protein of swine vesicular disease virus, was cloned from the SVDV HK/70 strain and inserted into retroviral vector pBABE puro, and expressed in PK15 cells by an retroviral expression system. The ability of the VP1 protein to induce an immune response was then evaluated in guinea pigs. Western blot and ELISA results indicated that the VP1 protein can be recognized by SVDV positive serum, Furthermore, anti-SVDV specific antibodies and lymphocyte proliferation were elicited and increased by VP1 protein after vaccination. These results encourage further work towards the development of a vaccine against SVDV infection.
基金supported by the National Natural Science Foundation of China(No.81460304)Guangxi Natural Science Foundation(No.2015GXNSFDA139020)a research program sponsored by the Health Bureau of Guangxi Zhuang Autonomous Region,China(No.Z2014298)
文摘This study bioinformatically analyzed the non-VP1 capsid proteins（VP2-VP4） of Coxasckievirus A6（CVA6）, with an attempt to predict their basic physicochemical properties, structural/functional features and linear B cell eiptopes. The online tools Sub Loc, Target P and the others from Ex PASy Bioinformatics Resource Portal, and SWISS-MODEL（an online protein structure modeling server）, were utilized to analyze the amino acid（AA） sequences of VP2-VP4 proteins of CVA6. Our results showed that the VP proteins of CVA6 were all of hydrophilic nature, contained phosphorylation and glycosylation sites and harbored no signal peptide sequences and acetylation sites. Except VP3, the other proteins did not have transmembrane helix structure and nuclear localization signal sequences. Random coils were the major conformation of the secondary structure of the capsid proteins. Analysis of the linear B cell epitopes by employing Bepipred showed that the average antigenic indices（AI） of individual VP proteins were all greater than 0 and the average AI of VP4 was substantially higher than that of VP2 and VP3. The VP proteins all contained a number of potential B cell epitopes and some eiptopes were located at the internal side of the viral capsid or were buried. We successfully predicted the fundamental physicochemical properties, structural/functional features and the linear B cell eiptopes and found that different VP proteins share some common features and each has its unique attributes. These findings will help us understand the pathogenicity of CVA6 and develop related vaccines and immunodiagnostic reagents.
