凋亡素诱导的肿瘤细胞凋亡

细胞凋亡是机体维持自身稳定的一种基本生理机制 ,并贯穿于整个生命活动。细胞凋亡异常可导致一些疾病的发生 ,如肿瘤的发生。同时 ,细胞凋亡的可诱导性也为肿瘤治疗提供了新的思路。凋亡素是来源于鸡贫血病毒的一个小分子蛋白。它能够选择性地诱导肿瘤细胞的凋亡 ,而对正常二倍体的细胞无任何毒副作用 ,并且正常细胞对凋亡素具有耐受性。凋亡素诱导肿瘤细胞凋亡既不需要依赖 p53 ,也不会被bcl-2的过表达所抑制。凋亡素还能诱导人成骨肉瘤细胞多药耐药株 R-OS-73 2的细胞凋亡。这些特点使凋亡素成为一种新型的候选抗肿瘤制剂。     

Effect of the VP3 gene of chicken anemia virus on canine mammary tumor cells

OBJECTIVE: To investigate the antitumor effect of the chicken anemia virus (CAV) VP3 gene in canine mammary tumor (CMT) cells. SAMPLE POPULATIONS: Established primary canine cell lines that originated from epithelial cells of resected CMTs and nonneoplastic mammary gland epithelial (MGE) cells. PROCEDURES: Expression vectors and lentiviral vectors encoding the VP3 gene from a Taiwan-Ilan isolate of CAV were used to deliver the VP3 gene into CMT cells and nonneoplastic MGE cells. Ectopic gene expression and the pro-apoptotic effect of the VP3 gene on CMT and nonneoplastic MGE cells by either transfection or viral infection were evaluated via immunofluorescence microscopy, western blot analysis, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling analysis. RESULTS: Overexpression of the enhanced green fluorescent protein-VP3 fusion protein was detected predominantly in the nuclei of CMT cells. In contrast, the VP3 protein was localized to the cytoplasm of nonneoplastic MGE cells. Among the fusion protein-expressing CMT cells, most underwent characteristic changes of apoptosis, whereas apoptosis was not detected in fusion protein-expressing, nonneoplastic MGE cells. Induction of apoptosis by VP3 gene overexpression in CMT cells was associated with the caspase-9-, but not the caspase-8-, mediated apoptosis pathway. CONCLUSIONS AND CLINICAL RELEVANCE: These data indicate that the VP3 gene of the CAV induces apoptosis in malignant CMT cells, but not in nonneoplastic canine MGE cells. On the basis of such tumor cell-specific killing, the VP3 gene may be a promising agent for the treatment of malignant mammary gland tumors in dogs.     

鸡贫血病毒实验感染雏鸡胸腺与骨髓的超微结构观察

用鸡贫血病毒 Ｃｕｘ １ 毒株接种于 １ 日龄 Ｓ Ｐ Ｆ 雏鸡，在确认感染成功的基础上，对感染雏鸡胸腺和骨髓的超微结构进行了观察。电镜观察表明，感染鸡骨髓和胸腺细胞的形态变化具有较典型的凋亡特征，如细胞膜出泡、核染色质凝结边集、细胞核裂解、出现凋亡小体等，此外还见有可能由病毒粒子形成的环状物。本试验为证明鸡贫血病毒能引起细胞凋亡提供了依据。     

凋亡素基因的克隆

为了探索应用凋亡素杀死肿瘤细胞的可能性,用ＰＣＲ方法扩增了鸡贫血病毒（ｃｈｉｃｋｅｎａｎｅｍｉａｖｉｒｕｓ,ＣＡＶ）的ＶＰ３基因（凋亡素）片段,然后将该片段重组于ｐＵＣ１９载体,并进行了限制性内切酶鉴定与序列分析,证实该片段与鸡贫血病毒Ｃｕｘ－１株的ＶＰ３ＤＮＡ序列一致,该ＤＮＡ全长３６３ｂｐ,编码１２１个氨基酸。     

Biological characteristics of chicken anemia virus regenerated from clinical specimen by PCR

Our previous genetic characterization of chicken anemia virus (CAV) in commercial broiler chickens in Alabama revealed a previously undetected polymorphism: a glutamine codon at VP1 position 22, in 7 of the 14 sequences. The novel glutamine codon was always found in association with a VP1 "hypervariable region" identical to CAV field isolates that replicate poorly in culture. The complete genome of CAV73, representative of the sequences with the novel polymorphism, was generated from cloned polymerase chain reaction (PCR) fragments amplified directly from naturally infected tissues. CAV73 had been detected in 31-day-old broilers submitted for examination for reasons unrelated to anemia. After electroporation of the cloned genomes into MDCC-CU147 lymphoblastoid cells, the regenerated CAV caused the culture to fail within 9 days, and the medium contained 5 X 10(6) TCID50 CAV/ml. Use of MDCC-CU147 cells was essential, as identical electroporation of MDCC-MSB1 cells failed to generate CAV able to destroy the culture within 8 wk. Regenerated CAV73 produced anemia and severe lymphocytic depletion of the thymus when inoculated into susceptible 3-day-old chickens and was reisolated from these chickens. Furthermore, it replicated in low- and high-passage MDCC-MSB1 cells similarly to a low-passage CAV field isolate that contains a different VP 1 "hypervariable region." The regeneration of CAV from PCR products directly from naturally infected carcasses, as performed in this study, provides a tool for the evaluation of distinct genetic polymorphisms that may be detected in specimens where infective virions are no longer available. Our results also provide some insight into the differential susceptibility of cell lines for low-passage CAV field isolates.     

鸡传染性贫血病毒诱导细胞凋亡的研究进展

鸡传染性贫血病毒是鸡传染性贫血病的病原体,能引起雏鸡贫血、淋巴组织萎缩、出血及免疫抑制,是导致许多疫苗免疫失败及雏鸡死亡的主要原因之一。该病毒在世界范围内广泛存在,是养鸡业潜在的巨大威胁。近年来的研究表明,鸡传染性贫血病毒主要是通过其编码的凋亡素诱导雏鸡胸腺和骨髓中的造血祖细胞凋亡而致病的,而凋亡素诱导细胞凋亡的能力与其在细胞中的核定位及半胱氨酸蛋白酶(caspase)等因素密切有关。文章就鸡传染性贫血病毒生物学特征、诱导细胞凋亡的现象及机制的研究进行了综述。     

Cloning and expression of chicken anemia virus VP3 protein in Escherichia coli

Purification of chicken anemia virus (CAV) VP3 protein, expressed in a prokaryotic expression system as histidine-tagged fusion protein is demonstrated in the present study. CAV particle was obtained from infected liver of chicken and DNA was extracted. The VP3 protein gene was amplified from the extracted DNA by polymerase chain reaction (PCR) and cloned. The recombinant expression construct (pTrc-VP3) was identified by PCR and sequencing analysis. Expression of VP3 protein with a molecular mass of approximately 21kDa was confirmed by Western blotting analysis with CAV-specific antibodies. The in vitro expressed VP3 protein was purified to near homogeneity by elution from the gel, as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. The purified VP3 protein was recognized by CAV antibodies in a Western blotting assay. This finding indicates that recombinant VP3 expressed in the pTrcHis2 vector system can be used as antigen to detect anti-CAV antibodies.     

鸡贫血病毒细胞凋亡素基因的原核表达及其免疫学活性

将鸡贫血病毒 (CAV)细胞凋亡素基因克隆入表达性载体 p GEX- 5 X- 3,在大肠杆菌中以融合蛋白的形式获得表达。再以表达产物免疫小鼠 ,制备抗 CAV凋亡素的多克隆抗体。以其对 CAV感染的 MSB1细胞作间接免疫荧光试验(IFA)检测呈阳性 ,表明表达产物保留了其相关的天然抗原特性。     

基因分析实现CAV VP1基因在大肠杆菌中的高效表达

通过分子生物学软件DNASTAR对CAV VP1的基因分析发现,CAV VP1基因的5端非抗原区编码蛋白的密码子中存在连续的大肠杆菌稀有密码子。为了在大肠杆菌中高效表达CAV VP1,文章研究扩增了不含5’端稀有密码子的CAV VP1基因,并将其插入原核表达载体pGEX-4T-1,构建了重组表达载体pGEX-VP1,成功进行了高效表达。电泳条带分析表明,融合蛋白的表达量在44%左右,为研究CAV VP1的抗原性提供了丰富的来源。     

鸡贫血病毒衣壳蛋白VP1基因的克隆、原核表达和纯化

根据GenBank中CAV哈尔滨分离株基因序列,设计出针对CAV VP1大片段(608 bp)的引物,利用PCR方法从CAV基因组序列中扩增出VP1基因的大片段(608 bp),按照正确的读码框克隆到原核表达载体pET32a( )上,得到含VP1大片段的pET32a( )重组子,转化大肠埃希菌BL21(DE3)感受态细胞,IPTG诱导重组蛋白表达,经SDS-PAGE和Western blotting检测发现有分子质量约42 ku的融合蛋白表达,与预期分子质量大小一致,通过Ni亲和层析柱纯化出融合蛋白,经Western blotting鉴定,融合蛋白与His单抗能够结合.CAV VP1基因的克隆表达及其融合蛋白的纯化为后续制备多克隆抗体和单克隆抗体提供了良好的抗原来源,也为研究VP1与其他CAV蛋白之间的相互关系奠定了基础.     

鸡贫血病病毒VP_2基因在大肠杆菌中的表达及其特性

将鸡贫血病病毒 (chicken anaem ia virus,CAV) VP2 基因克隆入表达性载体 p GEX- 5 X- 3,在大肠杆菌以谷胱甘肽转移酶 (GST)融合蛋白的形式获得了表达。以此表达产物免疫小鼠 ,制备抗 CAV VP2 的多克隆抗体。通过对 CAV感染的 MSB1细胞作间接免疫荧光试验 (IFA)检测 ,结果为阳性 ,这表明表达产物保留了 CAV相关的抗原特性。本研究为进一步探索 CAV VP2 的生物学特性奠定了基础。     

鸡贫血病毒哈尔滨分离株VP2基因克隆测序和比较

通过PCR方法克隆了从我国哈尔滨分离的一株鸡贫血病毒（CAV）的VP2基因，并对之进行了测序，该基因的开放读码框由65bp组成，编码216个氨基酸。通过将本次克隆的基因与GenBank收录的CAV的VP2基因比较，同源性至少为99％，未发现与本次克隆的VP2蛋白完全一致的CAV分离株，与之同源性最好的是CIA－1的VP2蛋白，相差1个氨基酸，与Cux-1也仅相差2个氨基酸，因此从该蛋白看CAV哈尔滨分离株的变异程度不很高。比较这27株病毒的VP2及其基因序列，发现共有31处核苷酸发生变异，这些变异将导致VP2的12个氨基酸变化，尽管他们散布于整个VP2，但在186到191号氨基酸区域存在一个没有报道过的变异程度相对较高的区域，CAV的VP2是相对较保守的蛋白。     

鸡贫血病毒vp3基因克隆、序列分析和比较

克隆了从我国哈尔滨分离的一株鸡贫血病毒（CAV）的vp3基因，并对之进行了测序。该基因的开放读码枢由366bp组成，编码121个氨基酸，氨基酸组成具有已报道VP3的典型特点。本次克隆的基因与GenBank收录的CAV的vp3基因进行序列比较，同源性至少为98％。与国内报道的山东株SJ1的vp3基因有3个核苷酸的差异，表明国内的CAV毒株已经产生了一些分化。在EMBL中比较本次克隆的VP3蛋白一级结构，与之差异最大的是马来西亚分离株的VP3，有5个氨基酸残基不同，同源性为96％。同时收集EMBL中的CAV的VP3蛋白绘制进化树，我国哈尔滨分离的CAV毒株与CIA进化关系最近，而与Cux-1的2个衍生株QDWX1、QDWX3进化关系最远。这些结果进一步证明了CAV在遗传方面是较保守的病毒，来自哈尔滨的CAV不是CAV的一个独立分支。     

Genome sequencing analysis of Brazilian chicken anemia virus isolates that lack MSB-1 cell culture tropism

Specific amino acid (aa) substitutions in VP1, VP2 and VP3 genes were reported as a distinctive feature of the American CIA-1 strain, characterized as having a variable rate of growth and tropism for different MSB-1 cell sublines [Renshaw RW, Soiné C, Weinkle T, O'Connell PH, Ohashi K, Watson S, et al. A hypervariable region in VP1 of chicken anemia virus mediates rate of spread and cell tropism in tissue culture. J Virol 1996;70(12):8872-8]. DNA sequencing of 878 nucleotides from twelve Brazilian CAV, eight of which tested for in vitro isolation in three different sources of MDCC-MSB1 cell line and identified as lacking capacity to propagate in any of these cells, were compared to sequence data available for CAV strains propagated or not in cell culture. Alignment of the deduced aa resulted in a lack of singled out amino acid substitutions in the partial genomic sequences of Brazilian isolates that would entirely contrast them to viruses propagated in MSB-1 cells, indicating that the combined VP1, VP2 and VP3 substitutions observed may not entirely account as sole determinants of CAV isolation and propagation in MDCC-MSB-1 cells.     

Biological and molecular characterization of chicken anemia virus isolates from Slovenia

The presence of chicken anemia virus (CAV) in Slovenia was confirmed by inoculation of 1-day-old chickens without antibodies against CAV and isolation of the virus on the Marek's disease chicken cell-MSB1 line and by polymerase chain reaction (PCR). Experimental inoculation of 1-day-old chickens resulted in lower hematocrit values, atrophy of the thymus, and atrophy of bone marrow. CAV was confirmed by PCR in the thymus, bone marrow, bursa of Fabricius, liver, spleen, ileocecal tonsils, duodenum, and proventriculus. The nucleotide sequence of the whole viral protein (VP)1 gene was determined by direct sequencing. Alignment of VP1 nucleotide sequences of Slovenian CAV isolates (CAV-69/00, CAV-469/01, and CAV-130/03) showed 99.4% to 99.9% homology. The VP1 nucleotide sequence alignment of Slovenian isolates with 19 other CAV strains demonstrated 94.4% to 99.4% homology. Slovenian isolates shared highest homology with the BD-3 isolate from Bangladesh. Alignment of the deduced VP1 amino acids showed that the Slovenian isolates shared 100% homology and had an amino acid sequence most similar to the BD-3 strain from Bangladesh (99.6%) and were 99.1% similar to the G6 strain from Japan and the L-028 strain from the United States. The Slovenian isolates were least similar (96.6%) to the 82-2 strain from Japan. A phylogeneric analysis on the basis of the alignment of the VP1 amino acids showed that CAV isolates used in the study formed three groups that indicated the possible existence of genetic groups among CAV strains. The CAV isolates were grouped together independent of their geographic origin and pathogenicity.     

Development of a DNA vaccine against chicken anemia virus by using a bicistronic vector expressing VP1 and VP2 proteins of CAV

In the present study, we describe the development of a DNA vaccine against chicken anemia virus. The VP1 and VP2 genes of CAV were amplified and cloned into pBudCE4.1 to construct two DNA vaccines, namely, pBudVP1 and pBudVP2-VP1. In vitro and in vivo studies showed that co-expression of VP1 with VP2 are required to induce significant levels of antibody against CAV. Subsequently, the vaccines were tested in 2-week-old SPF chickens. Chickens immunized with the DNA-plasmid pBudVP2-VP1 showed positive neutralizing antibody titer against CAV. Furthermore, VP1-specific proliferation induction of splenocytes and also high serum levels of Th1 cytokines, IL-2 and IFN-γ were detected in the pBudVP2-VP1-vaccinated chickens. These results suggest that the recombinant DNA plasmid co-expressing VP1 and VP2 can be used as a potential DNA vaccine against CAV.     

鸡贫血病毒VP1和VP2蛋白在家蚕中的联合表达

将鸡贫血病毒VP1和VP2基因分别克隆入转换载体pBacPAK8中，获得重组转移质粒pBac-vp1和pBac-vp2。以上两质粒分别与CvnⅠ酶切线性化的亲本病毒Bm-BacPAK6DNA共转染家蚕细胞，通过蓝白斑筛选，纯化得到重组病毒Bm-vp1和Bm-vp2。PCR分析表明Vp1和Vp2基因已整合进杆状病毒基因组中。将Bm-vp1和Bm-vp2共感染5龄家蚕，通过表达产物免疫SPF鸡产生的抗血清与CAV感染的MDCC－MSB1细胞的间接荧光抗体分析，证明表达产物能诱导鸡产生相应的抗体。该研究表明，表达VP1和VP2蛋白的重组家蚕杆状病毒（recombinant BmNPV）是很有前途的CAV亚单位疫苗的生产系统。     

Avian circovirus diseases: lessons for the study of PMWS

The diseases associated with psittacine beak and feather disease virus (BFDV), pigeon circovirus (PiCV) and goose circovirus (GoCV), which can be classified with porcine circovirus type 2 (PCV2) as members of the genus Circovirus of the family Circoviridae, have clinico-pathological features in common with post-weaning multisystemic wasting syndrome (PMWS), with which PCV2 infection is causally associated. Intracytoplasmic botryoid inclusions within macrophages and depletion of T and B lymphocytes are common histopathological features, and, in each case, affected animals usually exhibit ill-thrift and a predisposition to secondary infections, that is suggestive of an underlying immunosuppression. Although these avian diseases have been the subjects of relatively little research, their study can provide directly applicable lessons in the areas of diagnosis, epidemiology, pathogenesis and disease control for those charged with investigating PMWS. In keeping with its taxonomic separation as the only member of the genus Gyrovirus, the disease caused by chicken anaemia virus (CAV) differs histopathologically from the other circovirus-associated diseases. Most notably, the target cells of CAV have been identified as haemocytoblasts and precursor T lymphocytes, with lymphocyte depletion, which affects T cells only, occurring in cells directly infected with the virus. Nonetheless, CAV is the best-researched circovirus and provides excellent examples of both virus-induced immunosuppression and virus-virus interactions. The study of CAV-induced disease can therefore provide valuable, if less directly applicable lessons.     

鸡传染性贫血病毒VP3蛋白的原核表达及其单克隆抗体的研制

本研究首先利用同源重组一步克隆法将鸡传染性贫血病病毒(CIAV)的VP3基因克隆到pGEX-6P-1原核表达载体上,经IPTG诱导及SDS-PAGE分析成功获得了重组蛋白rGST-VP3的表达.随即以纯化的重组蛋白rGST-VP3免疫Balb/c小鼠,通过脾细胞与SP2/0细胞融合以及间接免疫荧光(IFA)筛选,获得2株稳定分泌CIAV-VP3抗体的杂交瘤细胞株,分别命名为CIAV-VP3-4D7和CIAV-VP3-4G8;亚型鉴定表明,CIAV-VP3-4D7和CIAV-VP3-4G8均为IgG1;效价测定发现,CIAV-VP3-4D7和CIAV-VP3-4G8的腹水间接免疫荧光效价分别为1:102400与1:12800;Western blot进一步证实,CIAV-VP3-4D7和CIAV-VP3-4G8均能识别重组蛋白rGST-VP3.本研究结果为后期研究VP3蛋白在CIAV致病中作用及其诱导凋亡分子机制奠定了坚实的物质基础.     

细小病毒衣壳蛋白功能研究进展

细小病毒是目前为止发现的最小的单股DNA病毒,在自然界分布极广并与多种疾病相关。该病毒衣壳中主要包含三种蛋白:VP1、VP2、VP3,这些衣壳蛋白参与了病毒感染的整个过程。VP1通过核定位信号(NLS)介导病毒感染性,协助病毒完成核内定位。VP2经"反受体"与细胞受体相互作用促进病毒进一步内化,与此同时VP1与VP2 N’末端共同作用完成核转运。裂解蛋白VP3仅存在于细小病毒科少数成员中,其功能未被完全确定,猜测可能是衣壳蛋白骨架。该病毒对外界理化因素有极强的抵抗力,如酸或热处理,甚至能逃避模式识别受体(PRRS)识别。通过对细小病毒感染过程中衣壳蛋白的作用及其在疾病治疗中的应用进行系统的总结及讨论,以期为相关科研工作者提供参考。