Varicella-zoster virus ORF1 gene product is a tail-anchored membrane protein localized to plasma membrane and trans-Golgi network in infected cells

Varicella-zoster virus (VZV) encodes five genes that do not have herpes simplex virus homologs. One of these genes, VZV open reading frame 1 (ORF1), encodes a membrane protein with a hydrophobic domain at its C-terminus that is predicted to be the transmembrane domain. However, the detailed characterization of ORF1 protein in infected cells has not been reported. Here, we produced mono-specific antibodies against ORF1 protein and characterized the gene products in infected cells. Western blot analyses showed the ORF1 polypeptides had apparent molecular masses of approximately 14-17 kDa. Furthermore, ORF1 was found to be a phosphoprotein by immunoprecipitation assay. In immunofluorescence assays, the VZV ORF1 protein was detected at both the plasma membrane and trans-Golgi network in both VZV-infected and ORF1-transfected cells. Moreover, ORF1 proteins associated with each other to form homodimer, and were incorporated into viral particles. The C-terminal hydrophobic domain was required for the association of ORF1 with the membrane structures, indicating that ORF1 protein is anchored to the membrane thorough its C-terminus, which is a transmembrane domain. Because ORF1 possesses a C-terminal transmembrane domain without an N-terminal signal sequence for its translocation to the ER lumen, ORF1 can be classified as a tail-anchored membrane protein. These results show that the N terminus of ORF1 protein faces the cytoplasm in infected cells and the tegument region in mature virions.     

A conserved region of the herpes simplex virus type 1 tegument protein VP22 facilitates interaction with the cytoplasmic tail of glycoprotein E (gE)

Herpes simplex virus type 1 (HSV-1) virions, contain a proteinaceous layer termed the tegument that lies between the nucleocapsid and viral envelope. Current evidence suggests that viral glycoprotein tails play a role in the recruitment of tegument-coated capsids to the site of final envelopment; vesicles derived from the trans-Golgi network. We have identified an interaction between VP22, an abundant tegument protein and the cytoplasmic tail of glycoprotein E (gE). This interaction was identified by coimmunoprecipitation studies and confirmed by a glutathione-S-transferase (GST) pulldown from infected cell lysates. Truncation mutagenesis suggests that residues 165-270 of VP22 facilitate the interaction with the cytoplasmic tail of gE. In fact, this region of VP22 is sufficient to bind to gE in the absence of additional viral proteins. Using a transfection/infection-based virion incorporation assay, residues 165-270 of VP22 fused to GFP competed efficiently with wild-type VP22 for packaging into assembling virus particles.     

Lack of trans-activation function for Maedi Visna virus and Caprine arthritis encephalitis virus Tat proteins

All lentiviruses contain an open reading frame located shortly upstream or inside of the env gene and encoding a small protein which has been designated Tat. This designation was mainly with respect to the positional analogy with the first exon of the trans-activator protein of the well studied human immunodeficiency virus type 1 (HIV-1). In this work we comparatively studied the trans- activation activity induced by Tat proteins of the small ruminant Maedi Visna virus (MVV) of sheep and Caprine arthritis encephalitis virus (CAEV) of goats on MVV and CAEV LTRs with that induced by the human lentivirus HIV-1 on its own LTR. The HIV-1 LTR alone weakly expresses the reporter GFP gene except when the HIV-1 Tat protein is coexpressed, the GFP expression is increased 60-fold. In similar conditions only minimal trans-activation increasing two- to three-fold the MVV and CAEV LTR activity was found with MVV Tat protein, and no trans-activation activity was detected in any used cell type or with any virus strain when CAEV Tat was tested. These results indicate that the small ruminant lentiviruses (SRLV) differ from the primate lentiviruses in their control of expression from the viral LTRs and put into question the biological role of the encoded protein named "Tat."     

乙肝病毒核心蛋白人源单链抗体在大肠杆菌中的表达

目的 获得可溶性的抗乙型肝炎病毒（HBV）核心蛋白（core)的人源单链可变区抗体（ScFv)，为得到纯度高、活力强的HBc-ScFv和进一步的抗HBV治疗奠定基础。方法 采用噬菌体表面展示技术，以重组的HBV核心蛋白为包被抗原，从噬菌体单链可变区抗体库中经过5轮“吸附－洗脱－扩增”筛选过程，获得抗原结合活性较强的乙型肝炎核心蛋白人源单链可变区抗体ScFv片段克隆，并对其进行DNA序列及免疫活性测定。从噬菌体抗体阳性克隆中提取质粒转化大肠杆菌HB2151，IPTG诱导表达乙型肝炎核心蛋白可溶性人源单链可变区抗体，ELISA和western blot检测其抗原结合特异性。结果 克隆了乙型肝炎核心蛋白的单链可变区抗体基因；经DNA酶切和序列分析表明，该抗体基因由771个碱基组成；ELISA和western blot结果表明：在大肠杆菌HB2151中经IPTG诱导表达的可溶性乙型肝炎核心蛋白的单链可变区抗体，具有结合乙型肝炎核心蛋白的特异性和免疫活性。结论 克隆、鉴定并在大肠杆菌HB2151中表达了可溶性的HBc-ScFv。     

抗HBV中和抗体MA18/7轻链可变区VL与GFP融合蛋白的表达及生物活性测定

目的 :在大肠杆菌中表达抗HBV中和抗体MA18/7轻链可变区基因 (VL)与增强型绿色荧光蛋白 (EGFP)的融合蛋白 ,并测定其生物学活性。方法 :应用基因工程技术 ,将EGFP基因克隆到载体pTO T7中构建原核表达载体。然后将MA18/7的VL基因按照读码框插入到无终止密码子TAA的EGFP基因的 5′末端 ,构建融合蛋白表达载体。通过ELISA和相对荧光强度测定在大肠杆菌中表达的融合蛋白的活性。结果 :构建了EGFP MA18/7 VL 表达载体。SDS PAGE表明 ,融合蛋白主要以包涵体的形式存在。荧光测定显示 ,融合蛋白保持了GFP的荧光性质。ELISA的结果表明 ,融合蛋白与重链可变区 (VH)片段结合成的Fv ,能特异性地识别HBVpre S1抗原。结论 :成功地获得具有良好生物学活性的融合蛋白 ,可用于进一步的研究。     

The effects of targeting the vaccinia virus B5R protein to the endoplasmic reticulum on virus morphogenesis and dissemination

The consequence of redirecting the vaccinia virus (VV) B5R protein to the endoplasmic reticulum (ER) has been investigated by the addition of an ER retrieval signal KKSL (K(2)X(2)) to the B5R C-terminus. This mutant B5R gene and a version of the gene with the inactive ER retrieval sequence KKSLAL (K(2)X(4)) were inserted into the thymidine kinase locus of a VV mutant lacking the B5R gene, vDeltaB5R. Similar levels of B5R protein were made by each virus, but the B5R-K(2)X(2) protein remained sensitive to endoglycosidase H and colocalised with protein disulphide isomerase in the ER. In contrast, the B5R-K(2)X(4) protein colocalised with 1, 4-galactosyltransferase in the trans-Golgi network. Electron microscopy revealed that even when the B5R protein was redirected to the ER, intracellular mature virus particles were wrapped by cellular membranes to form intracellular enveloped virus particles, although more incompletely wrapped particles were evident compared with wild type. These intracellular enveloped virus particles were, however, unable to efficiently induce the polymerisation of actin and the plaque size formed by vB5R-K(2)X(2) was small. Nevertheless, the amount and specific infectivity of EEV produced by vB5R-K(2)X(2) were similar to those of wild type, despite the dramatic reduction in the amount of B5R protein present in vB5R-K(2)X(2) EEV.     

The baculovirus P10 protein of Autographa californica nucleopolyhedrovirus forms two distinct cytoskeletal-like structures and associates with polyhedral occlusion bodies during infection

The role of the microtubule-associated P10 protein of baculoviruses is not yet understood. P10 has previously been linked with the formation of a number of cytoskeletal-like or cytoskeleton-associated structures in the nucleus and cytoplasm, thought to be involved in the morphogenesis of virus polyhedral occlusion bodies. The formation of these structures was studied by immunofluorescence laser scanning confocal microscopy in TN368 cells, a model system amenable to the study of virus interaction with the host cell cytoskeleton. We show that the Autographa californica nucleopolyhedrovirus P10 protein forms two distinct cytoskeletal-like structures, microtubule-associated filaments and perinuclear tubular aggregates. P10 also associates with polyhedral occlusion bodies. Depolymerisation of the microtubule network with colchicine prevents formation of P10 filaments but not of P10 tubules. Colchicine treatment enhances the association of P10 with occlusion bodies. Transient expression of P10 showed that both filaments and tubules can form in the absence of other viral proteins. We postulate a number of possible roles of the P10 protein during virus infection and morphogenesis.     

抗HTNV mAb 3G1单链抗体基因转化植物的研究

目的 构建抗HTNV mAb 3G1 scFv的转基因拟南芥植株.方法 从含有3G1 scFv基因的重组质粒中酶切获得含有该目的基因的表达框,将其克隆入载体pCAMBIA2301,构建植物表达载体3G1scFv-pCAMBIA2301.通过农杆菌介导的花粉管法将其转入拟南芥,PCR和Southern blotting检测是否获得转基因植株.组织化学染色检测标记基因GUS是否表达.结果 限制性内切酶酶切鉴定结果证明3G1 scFv基因被成功克隆入植物表达载体pCAMBIA2301,构建获得3G1scFv-pCAMBIA2301重组质粒.PCR和Southern blotting检测证明获得抗HTNV mAb 3G1 scFv的转基因拟南芥植株.组织化学染色结果表明,标记基因亦高效表达.结论 成功地将外源基因转入拟南芥中并表达,为进一步研究利用植物表达医用抗体奠定了基础.     

Association of Two Membrane Proteins Encoded by Herpes Simplex Virus Type 2, UL11 and UL56

Herpes simplex virus (HSV) acquires envelope by budding into trans-Golgi network (TGN)-derived vesicles. Previous studies showed that the UL11 gene product enables efficient virion envelopment and export from infected cells and is incorporated into virions as tegument protein. At its N-terminus, UL11 is dually acylated by myristoic and palmitoic acids. Fatty acylation of UL11 provides both membrane binding strength and Golgi-targeting specificity. We show here that UL11 interacts with UL56 protein, a tail-anchored type II membrane protein encoded by HSV, which associated with the Golgi apparatus and cytoplasmic vesicles. We previously showed that UL56 is involved in vesicular transport in infected cells. The UL11–UL56 complex localized to the perinuclear region of the cytoplasm in infected cells. Fatty acylation of UL11 was important for the formation of the UL11–UL56 protein complex. Taken together, our results identify a novel interaction between two HSV proteins facilitated by mutual interactions with Golgi-derived vesicles.     

骨形态发生蛋白2对退变椎间盘组织学和Ⅰ，Ⅱ型胶原的影响

背景：研究表明,退变椎间盘细胞外基质的主要变化是Ⅱ型胶原和蛋白多糖含量的减少和Ⅰ型胶原含量的增加。 目的：观察腺相关病毒介导的骨形态发生蛋白2基因(AAV-BMP-2)对兔退变腰椎间盘内髓核Ⅰ,Ⅱ型胶原的影响。 方法：将12只新西兰大白兔L2-3,L3-4,L4-5,L5-6椎间盘针刺制造退变模型后随机分为3组,每组4只。其中AAV-BMP-2组兔椎间盘注射AAV-BMP-2,AAV组兔椎间盘注射不携带目的基因的空载体,生理盐水组兔椎间盘注射生理盐水,注射后第8周处死动物取其相应的椎间盘常规石蜡包埋,组织切片,以苏木精-伊红染色观察其髓核组织学变化,免疫组织化学法检测髓核组织Ⅰ型、Ⅱ型胶原表达并进行半定量分析。 结果与结论：普通苏木精-伊红染色结果显示AAV-BMP-2组椎间盘内髓核细胞数目较多,呈单个或者簇状分布,髓核结构清晰,无纤维样组织填充。而AAV组和生理盐水组的组织结构相似,髓核内细胞数目少,髓核皱缩干瘪,细胞间为纤维样组织填充且排列紊乱。免疫组织化学染色显示：AAV-BMP-2组椎间盘髓核内Ⅱ型胶原的表达均高于AAV组和生理盐水组(P < 0.05);AAV-BMP-2组椎间盘髓核内Ⅰ型胶原的表达均低于AAV组和生理盐水组(P < 0.05)。结果说明,体内转染AAV-BMP-2能抑制椎间盘髓核细胞表达Ⅰ型胶原,促进椎间盘髓核细胞表达合成Ⅱ型胶原,提示维持椎间盘内胶原的含量、种类,可维持椎间盘内组织学的结构和形态,稳定髓核细胞生长环境,延缓椎间盘的退变。     

Ecotropic murine leukemia virus envelope protein affects interaction of cationic amino acid transporter 1 with clathrin adaptor protein complexes, leading to receptor downregulation

Mouse cationic amino acid transporter 1 (mCAT1) serves as the receptor for ecotropic murine leukemia virus (eMuLV). It has been shown that mCAT1 is expressed on the basolateral surface of polarized epithelial MDCK cells. However, little is known about the mechanisms involved in the intracellular trafficking of mCAT1. Using the green fluorescent protein-tagged mCAT1 expressed in MDCK cells, we report here that mCAT1 is physically associated with clathrin adaptor protein complex 1 (AP-1) implicated in protein trafficking from trans-Golgi network (TGN) to the basolateral surface. When the cells were infected with eMuLV, reduction of cell surface mCAT1, as well as a concomitant decrease in mCAT1-AP-1 association, was observed while association of mCAT1 with AP-3 involved in the TGN-to-lysosome trafficking was increased. Similar results were obtained when eMuLV envelope protein alone was expressed. The results may provide useful insights into the mechanism by which a simple retrovirus downregulates its receptor.     

The UL4 protein of equine herpesvirus 1 is not essential for replication or pathogenesis and inhibits gene expression controlled by viral and heterologous promoters

Defective interfering particles (DIP) of equine herpesvirus 1 (EHV-1) inhibit standard virus replication and mediate persistent infection. The DIP genome is comprised of only three genes: UL3, UL4, and a hybrid gene composed of portions of the IR4 (EICP22) and UL5 (EICP27) genes. The hybrid gene is important for DIP interference, but the function(s) of the UL3 and UL4 genes are unknown. Here, we show that UL4 is an early gene activated solely by the immediate early protein. The UL4 protein (UL4P) was detected at 4 hours post-infection, was localized throughout the nucleus and cytoplasm, and was not present in purified virions. EHV-1 lacking UL4P expression was infectious and displayed cell tropism and pathogenic properties in the mouse model similar to those of parental and revertant viruses. Reporter assays demonstrated that the UL4P has a broad inhibitory function, suggesting a potential role in establishing and/or maintaining DIP-mediated persistent infection.     

A host cell membrane protein, golgin-97, is essential for poxvirus morphogenesis

Acquisition of the membrane and genome encapsidation is an important step in the replication of enveloped viruses. The biogenesis of the poxviral primary membrane and the core as well as the mechanisms of their maturation are poorly understood. Using RNA interference approach, we demonstrate that a cellular trans-Golgi network membrane protein, golgin-97, is essential for virus replication. Analysis of the virion morphology in the cells depleted of golgin-97 shows that the protein is required for the virus morphogenesis and, in particular, for the formation of the first infectious virus form, mature virus, but not its precursor, immature virus. This suggests that golgin-97 may be involved in the maturation of the virus core and, potentially, the virus membrane.     

三叶因子3对甲状腺乳头状癌细胞周期的影响及机制

目的 探讨三叶因子3 (TFF3)基因沉默对人甲状腺乳头状癌TPC-1和BCPAP细胞增殖及细胞周期的影响及相关分子机制。 方法 包装TFF3 shRNA 慢病毒载体,病毒感染获得TPC-1和BCPAP稳转细胞株;生长曲线和集落形成实验检测沉默TFF3后细胞增殖状况;流式细胞术检测TFF3基因对TPC-1和BCPAP细胞周期的影响;实时定量聚合酶链反应(Real-time PCR)检测P27、P21和cyclin D1、周期蛋白依赖性激酶（CDK）4 mRNA的表达情况;免疫印迹法(Western blotting)、免疫细胞化学染色检测周期相关蛋白P27、P21、cyclin D1、CDK4和蛋白激酶B（Akt）、pAkt的蛋白表达水平。 结果 成功包装TFF3 shRNA 慢病毒载体,病毒液感染获得TPC-1和BCPAP稳转细胞株;生长曲线和集落形成实验结果显示,沉默TFF3后,细胞增殖能力减弱;流式细胞术结果显示,与对照组相比,TFF3基因沉默组G₁期的细胞比例明显增高(*P<0.05),S和G2期的细胞比例明显下降（*P<0.05);TFF3沉默组TPC-1和BCPAP细胞中的P27、P21 mRNA和蛋白明显上调（*P<0.05),而cyclin D1,CDK4 mRNA和蛋白表达降低（*P<0.05);4株细胞Akt蛋白含量无明显差异,但沉默TFF3组磷酸化蛋白激酶B（pAkt）表达减弱;免疫细胞化学染色显示,cyclinD1阳性蛋白位于癌细胞胞核,P27、P21蛋白表达于胞质和胞核,且沉默TFF3后在细胞核中阳性信号增强,细胞质中阳性表达降低。 结论 沉默TFF3可明显延长甲状腺癌细胞周期,抑制细胞的增殖,可能与抑制磷脂酰肌醇3-激酶/蛋白激酶B（PI3K/Akt）通路相关蛋白的表达有关。     

The membrane on the surface of hepatitis E virus particles is derived from the intracellular membrane and contains trans-Golgi network protein 2

Our previous studies demonstrated that hepatitis E virus (HEV) requires the multivesicular body (MVB) pathway to release virus particles, suggesting that HEV utilizes the cellular ESCRT machinery in the cytoplasm, not at the cell surface, to be released from infected cells. In this study, we generated a murine monoclonal antibody (mAb) against the membrane-associated HEV particles to examine whether the membrane is derived from intracellular vesicles or the cell surface. An established mAb, TA1708, was found to capture the membrane-associated HEV particles, but not the membrane-dissociated particles or fecal HEV, in an immunocapture RT-PCR assay. Furthermore, digitonin treatment confirmed that the membrane on the surface of cell-culture-generated HEV particles was a lipid membrane. Double immunofluorescence staining revealed that mAb TA1708 specifically recognizes trans-Golgi network protein 2 (TGOLN2), an intracellular antigen derived from the trans-Golgi network. Supporting these findings, HEV particles with lipid membranes and ORF3 proteins on their surface were found abundantly in the lysates of HEV-infected cells. These results indicate that HEV forms membrane-associated particles in the cytoplasm, most likely by budding into intracellular vesicles, and that the released HEV particles with a lipid membrane retain the antigenicity of TGOLN2 on their surface.