Dynamic Pathology and Antigen Location Study on Broiler Breeders with Coinfection of Marek's Disease Virus and Reticuloendotheliosis Virus

To further understand the generation and development of coinfection of Marek＇s disease virus （MDV） and reticuloendotheliosis virus （REV） in broiler breeders, and then find the method and optimal time of differential diagnosis for complex clinic multiple infection, the authors studied the pathohistological changes, apoptosis, immunohistochemistry （immunofluorescence）, and ultrastructure of tumor tissues of broiler breeders inoculated with MDV and REV. The study showed that proliferation of small lymphocytes was seen in the main organs at the age of 1 week, then immature lymphocytes, all kinds of lymphocytes, primitive reticulum cells, and Marek＇s disease cells （MDCs） were observed at 2-9 weeks. Apoptosis of lymphocytes could not be seen until the age of 10 weeks in the immune system. Immunohistochemistry detection showed that the positive signs of MDV and REV antigen were observed in the main organs at 2 weeks of age. Multi-morphology lymphocytes, MDV, and REV, mitotic figures and apoptosis of lymphocytes were observed with the help of transmission electron microscopy. MDV cooperating with REV promotes the course of disease of coinfection. Differential diagnosis can be done by immunohistochemistry in the early stage （before 2 weeks）, and histopathology in the late stage （post 4 weeks）. MDCs, primitive reticulum cells, immature lymphocytes, and two kinds of virions can serve as a basis for bistopathology differential diagnosis.

Comparison of Immune Effect of Four Commercial Marek's Disease Vaccines in Wenchang Chicken

Marek＇s disease（MD） is a lymphoproliferative disease of domestic chickens caused by a highly infectious,oncogenic alpha-herpesvirus known as Marek＇s disease virus（MDV）.The aim of this study was to compare the efficacy of four commercial MDV vaccines in Wenchang chicken.The 1-day old Wenchang chickens tested were injected with one of four different vaccines or not unvaccinated as control;five days later,they were then challenged by virulent MDV strain MD5.The results showed that,in comparison with HVT vaccines,the CVI988 vaccine gave the immunized chickens more potent immunities against challenges of MDV strain MD5.

重组马立克病病毒CVI988／Rispens的构建

根据I型马立克病病毒(MDV)强毒GA株基因序列,设计两对引物,用PCR方法扩增出CVI988／Rispens株的US10及其侧翼序列,分别克隆入pUC18载体中。经测序检测正确后,进一步插入含CMV启动子的绿色荧光蛋白 (EGFP)基因表达盒,获得了含EGFP报告基因的转移载体质粒pPUC18-US10-EGFP。通过同源重组,成功地筛选出表达EGFP的重组病毒rCVI988-EGFP,经传代证明重组rCVI988-EGFP在感染的CEF细胞中能稳定表达EGFP。结果表明:构建的重组转移载体质粒正确,US10是MDV复制非必需片段,为进一步利用US10区构建重组MDV多价基因工程疫苗奠定了基础。

用 Western Blot 法鉴定感染鸡外周血淋巴细胞中马立克氏病毒抗原

马立克氏病毒是鸡的一种高度致肿瘤性疱疹病毒，主要以淋巴瘤为特征，有关该病毒的致病机理还不清楚。本研究利用澳大利亚分离的ＭＤＶ致病毒株ＭＰＦ５７感染１日龄ＳＰＦ雏鸡，并在感染后４周对其外周血淋巴细胞中的ＭＤＶ特异性抗原进行了检测。结果表明，临床上呈急性感染并伴有明显症状的鸡的外周血淋巴细胞中的ＭＤＶ抗原分子量主要为２８、７３、６０和４９ｋＤａ；而无明显症状的鸡的外周血淋巴细胞中的ＭＤＶ抗原分子量主要为７３ｋＤａ。试验证明，Ｗｅｓｔｅｒｎｂｌｏｔ是一种较好的检测病毒抗原的方法，可以检测到荧光抗体方法检测不到的淋巴细胞中的ＭＤＶ特异抗原。

MDV Rispens 株B抗原基因的酶切及序列分析

将马立克氏病病毒（ＭＤＶ）血清Ｉ型Ｒｉｓｐｅｎｓ株接种原代鸡胚成纤维细胞（ＣＥＦ），待出现８０％以上细胞病变后收获，提取细胞和病毒的总ＤＮＡ．以此为模板，根据Ｂ抗原基因核苷酸序列设计一对引物，通过聚合酶链反应（ＰＣＲ）扩增出一条约２．８５ｋｂ的特异性条带，双酶消化后克隆至质粒ｐＵＣ１９，酶切分析表明该病毒的Ｂ抗原基因上ＨｉｎｄⅢ、ＥｃｏＲⅤ、ＢａｍＨⅠ、ＥｃｏＲⅠ的酶切位点分布与ＲＢ１Ｂ株、ＧＡ株的完全相同，进一步序列分析表明。

Expression and intercellular trafficking of the VP22 protein of CVI988/Rispens vaccine strain of Marek’s disease virus

The viral protein 22 (VP22) in the tegument of Marek’s disease virus serotype 1 (MDV-1) plays an im-portant role in cell-to-cell spread and viral propagation. Antiserum against the carboxyl terminus of VP22 was prepared by immunizing mice with recombinant VP22 expressed in E. coli, and used to in-vestigate its expression in chicken embryo fibroblast (CEF) cells infected with different MDV-1 strains. At an infection dose of PFU=50, intercellular trafficking of the VP22 into the nuclei of the surrounding receipt cells was detected as early as 3 hours post infection. By 6 hours after infection (before viral plague formation), the protein was detected in the whole nuclei of the recipient cells with no difference among MDV-1 strains CVI988/Rispens, GA and RB1B. Intra-nuclear accumulation of the VP22 protein was further increased when the viral plagues started to form. These results indicate that, albeit the ex-istence of the 201TKSERT206 deletion, the VP22 of the CVI988/Rispens vaccine strain has also intercel-lular-trafficking function, which might serve as a potential alternative delivering protein instead of virulent strains VP22.

Analysis of DNA methylation of CD79B in MDV-infected chicken spleen

Marek’s disease(MD),an immunosuppressive disease induced by Marek’s disease virus(MDV),provides an ideal model for studying diseases caused by a carcinogenic virus.CD79 B is a B-cell antigen receptor complex-associated protein β-chain precursor which is involved in the activation,proliferation,differentiation of B-cell and the transmission of downstream signals.This study analyzed CD79 B gene mRNA expression and methylation by two schemes#20(5′flanking to intron 1)and#27(intron 2 to intron 3),between MDV-infected tumorous spleens(TS)and non-infected spleens(NS).Results showed that average methylation levels of CpGs in #20 and #27 were higher in TS than in NS(P<0.05),while,CD79 B mRNA expression was lower in TS than in NS(P<0.01).Six of 40 CpG sites showed significantly(P<0.05)different methylation levels between TS and NS.Correlation analysis showed that the average methylation level rather than a single site methylation level in #20 affected(P<0.05)mRNA expression.Collectively,it was found that the change of CD79 B gene expression after MDV infection might be partly explained by modification of DNA methylation.

Study on the structure of heteropolymer pp38/pp24 and its enhancement on the bi-directional promoter upstream of pp38 gene in Marek’s disease virus

In the latest report, Chloramphenicol acetyltransferase (CAT) gene was used as a reporter to investi-gate the influence of pp38 on its upstream bi-directional promoter, and it was found that the co-expression of pp38 and pp24 can significantly enhance the transactivity of the bi-directional pro-moter between pp38 gene and 1.8-kb mRNA transcript in genome of Marek’s disease virus (MDV). In this study, enhanced green fluorescence protein (EGFP) gene was used as another reporter to further investigate the promoter activity. The transfection shows the promoter has the complete activity under the condition of co-expression of pp38 and pp24 in the same cells. Immunoprecipitation test was used to verify the structure of pp38/pp24 heteropolymer. The pp38-specific monoclonal antibody H19 was used in this test, and pp38, pp24 or both were prepared from the pcDNA-pp38, pcDNA-pp24 or pBud-pp38-pp24 transfected chicken embryonic fibroblast (CEF), respectively. Immunoprecipitation indicates that pp24 could be co-precipitated with pp38 by MabH19, implying that pp24 and pp38 were able to form a heteropolymer in the natural condition. The two separated tests clarify that pp38 and pp24 form a heteropolymer, which enhances the activity of the promoter.

MDV-1 VP22 conjugated VP2 enhancing immune response against infectious bursal disease virus by DNA vaccination in mice

VP22 of Marek’s disease virus serotype 1 (MDV-1) could function in protein transduction. In this study, an infectious bursal disease virus VP2 gene was fused to the carboxyl termini of VP22. It showed that the fusion protein did not spread into the bystander cells from the cells transfected with pVP22-VP2, as the VP22 alone could. The VP22 proteins were found to be translocated into all the nuclei in the neighboring COS-1 cells, as analyzed by a fluorescence assay. Although mice were immunized with the recombinant DNAs mixed with polyethylenimine (PEI) at a dose of 1:2, it failed to enhance the antibody response against IBDV VP2, as measured by the indirect ELISA assay, yet the cell mediated immune response was significantly increased. The ratio of CD8+/CD4+ T cells was significantly increased in the immunized group with the fusion genes, compared with the group immunized with VP2 (P<0.05). Our results demonstrated that VP22 indeed enhances the cell-mediated response in the fused VP2 in a mice model system, possibly due to the fact that the IBDV VP2 could be carried into the surrounding cells at a limited level under pressure from MDV VP22.

传染性法氏囊病病料中MDV、CAV、REV的共感染检测

从江苏、山东、浙江、河南、上海、广西、云南等地收集根据临床表现及病理变化诊断为传染性法氏囊病( IBD)的病鸡法氏囊样品 66份 ,用相应的核酸探针及斑点杂交法分别检测样品中鸡传染性贫血病病毒( CAV)、马立克氏病病毒 ( MDV)、网状内皮细胞增生病病毒 ( REV)的感染 ;用抗 IBD血清做琼扩检测 IB-DV。结果显示 ,部分地区病料中这些病毒有不同程度的二重感染、三重感染甚至四重感染。提示在研究特定毒株 IBDV的毒力时 ,应考虑多重感染对致病性的影响。

两株马立克病病毒的分离及相关致病基因序列的比较

为了解国内鸡群马立克病（MD）流行毒株的遗传特征,采用细胞培养、间接免疫荧光等方法从江苏省2个鸡场送检病鸡中分离鉴定出2株马立克病病毒（MDV）Ⅰ型毒株,采用PCR方法扩增两分离毒株的vIL-8、pp38、meq等病毒致病相关基因,所得序列用DNAStar软件与GenBank上登录的参考毒株进行比较分析。结果显示,两分离毒株的序列同源性为99.7%-100%,与MDVⅠ型强毒及超强毒株的同源性为99.3%-99.8%,具有强毒特征;两分离毒株的meq基因与其他4个国内分离强毒株的序列完全一致,在pp38基因编码的氨基酸序列中第109位均为甘氨酸而不是国外GA等毒株的谷氨酸,这与以前报道的另外3个中国野毒株一致。提示,这些变异可能是国内MDV流行强毒的遗传性特征。

表达马立克氏病病毒gI基因的重组鸡痘病毒的构建

以马立克氏病病毒 (MDV) 648株基因组DNA为模板 ,用PCR方法扩增 gI基因 ,将其插入到鸡痘病毒转移载体pFG1 1 75 1 ,通过脂质体方法转染鸡痘病毒 (FPV)感染的鸡胚成纤维细胞 (CEF) ,用蓝斑筛选方法纯化 4次 ,得到重组FPV ,用PCR方法证实 gI已插入到FPV基因组中 ,以间接免疫荧光试验鉴定重组FPV在CEF中表达了 gI基因 ,重组FPV命名为rFPVMDV648gI。

抗MDV-1 VP22羧基端单克隆抗体的制备与免疫学特性鉴定

目的:制备抗血清I型马立克氏病病毒(MDV-1)VP22的单克隆抗体(mAb),并鉴定其免疫学特性。方法:在原核系统中表达VP22羧基端区域(94-243aa),获得融合表达产物GST-VP22C。将该表达产物切胶免疫小鼠,利用杂交瘤技术制备抗MDV-1 VP22C的mAb,并通过ELISA、间接免疫荧光(IFA)、Western blot鉴定其特性。结果:获得了2株可稳定分泌抗MDV-1 VP22C的mAb的杂交瘤细胞,命名为3F7、4E4。IFA鉴定表明,两株mAb均能与感染MDV-1的成纤维细胞反应,其中,3F7 mAb染色呈现MDV空斑,而4E4mAb呈现整个单层的细胞核荧光。ELISA和Western blot分析表明,3F7能与杆状病毒表达的VP22反应,4E4不具备该特性。对3F7 mAb进一步鉴定,确定了该mAb针对的具体位置在94-193aa处,是蛋白转导域的预测位置。结论:成功地制备了抗MDV-1 VP22C的mAb,为深入研究VP22蛋白的转导功能提供了有用的试剂。

狄高辛标记DNA探针对鸡马立克氏病的流行病学研究

用狄高辛标记的Ⅰ型马立克氏病病毒特异性ＤＮＡ探针，对自然感染鸡羽囊、人工感染鸡羽囊和脏器、同居感染鸡羽囊进行了检测。结果表明，自然感染鸡，其羽囊最早出现阳性的日龄为４２日龄，随日龄增大，羽囊阳性检出率升高，１５０日龄达最高峰（２６．７％）。以后则阳性率显著下降（６月龄为０．４８％，１年以上为０．２４％）。鸡人工感染马立克氏病国际标准强毒（ＭＤＶ－ＧＡ强毒）后３ｄ，就可从５只鸡中３只的心、肝、肺、肾、法氏囊、胸腺、肌胃等脏器检出Ⅰ型ＭＤＶ－ＤＮＡ；２５ｄ，５只鸡的脏器均能检出ＭＤＶ－ＤＮＡ；同时，感染后１０ｄ，就可从羽囊检出ＭＤＶ－ＤＮＡ，１５ｄ羽囊检出阳性率达１００％。同居感染鸡从羽囊排毒的最早时间为同居后３１ｄ，即接触强毒２１ｄ后开始持续排毒，直至死亡。

表达马立克氏病病毒gI基因重组鸡痘病毒的免疫原性

以鸡痘病毒为载体,构建含马立克氏病病毒(MDV)gI基因的重组鸡痘病毒(rFPV),并在鸡胚成纤维细胞(CEF)中表达gI基因,用重组FPV(命名为rFPV MDV648gI)感染CEF,结果显示:rFPV MDV648gI能在CEF中稳定复制。进一步用rFPV MDV648gI接种无特定病原(SPF)鸡皮下组织,结果表明:鸡对rFPV MDV648gI具有抗体反应性。

马立克氏病强毒株感染鸡T细胞受体亚群动态变化的研究

为深入探讨鸡马立克氏病Ｔ细胞受体亚群的变化与疾病发生与发展的相互关系，本实验以马立克氏病强毒株人工感染１日龄ＳＰＦ雏鸡，在不同的感染期，以流式细胞仪分析脾脏、胸腺、外周血淋巴细胞中ＴＣＲ１＋和ＴＣＲ２＋Ｔ细胞的动态变化。结果表明，感染鸡脾脏中ＴＣＲ１＋Ｔ细胞异常增高，而ＴＣＲ２＋Ｔ细胞在脾脏和外周血中表现为暂短的升高，其后迅速下降。ＴＣＲ１＋Ｔ细胞与ＴＣＲ２＋Ｔ细胞的这种异常变化是ｖＭＤＶ感染雏鸡后Ｔ细胞表型变化的重要特征之一。

我国自然发病鸡群中MDV、REV和CAV共感染的检测

从山东、河南、河北、北京、江苏、广东、广西、四川、吉林、辽宁、台湾11 省42 个不同鸡群收集临床有发病表现的828只病、死鸡的病理组织样品,用点杂交方法检测各个样品中马立克氏病病(Marek′s disease virus,MDV)、网状内皮细胞增生病病毒(Reticuloendotheliosis virus,REV) 、鸡传染性贫血病病毒(Chicken anemia virus,CAV)的感染情况。结果表明:828 只病鸡中这三种病毒的检出率均相当高,分别为83. 94% (MDV)、61. 0% (CAV)和57.25%(REV),并且存在非常严重的双重感染(31. 16%)和三重感染(44. 69%),单重感染和阴性个体仅占15.34%和8.82%;在42个鸡群中的29个存在三重感染,占鸡群总数的69.05%,5个鸡群存在MDV和CAV的共感染,3个鸡群存在MDV和REV的共感染,二重感染占鸡群总数的19.05%,仅有2个鸡群未检测到这三种病毒;在地域分布上,11个省份均检测到了MDV、CAV和REV,表明了这三种病毒在我国的广泛分布及其在生产鸡群中的混合感染是导致当前我国养禽业生产性能下降、条件致病性疾病发生严重、临床腺胃肿大症状发生的重要原因。

马立克氏病病毒致瘤相关基因meq在不同病变组织中的变化

以MSB-1肿瘤细胞建立的马立克氏病为病理模型,利用PCR技术扩增不同病变组织中的meq基因,构建meq基因重组阳性质粒,测定和比较它们的核苷酸和氨基酸序列。结果显示,与L-meq(1 200 bp)和标准株GA的meq(1 020 bp)比较,MSB-1细胞和脾脏肿瘤组织的meq基因(1 197 bp)、羽髓meq基因(1 017 bp)分别相应缺失3个碱基(CCA);MSB-1细胞和脾脏肿瘤组织的meq基因具有与L-meq相同的180 bp插入序列;氨基酸序列也发生相应变化。结果表明,meq基因在不同病变组织中的核苷酸序列发生了变化,这种变化可能与马立克氏病病毒的致瘤机制有关。

致弱Ⅰ型MDV pp38基因同源物的克隆和序列分析

将致弱Ⅰ型马立克氏病病毒（ＭＤＶ）感染的细胞基因组ＤＮＡ的ＥｃｏＲⅠ酶切产物建于ｐＵＣ１８质粒载体文库中，以ｄｉｇｏｘｉｎｇｅｎｉｎ标记的含有强毒ＧＡ株ＭＤＶｐｐ３８基因克隆片段作为探针，进行原位杂交反应，初步筛选出阳性重组质粒，进一步用ＥｃｏＲⅠ酶切分析筛选到含ｐｐ３８基因同源物的重组ｐＵＣ１８质粒．序列分析表明该ｐｐ３８基因同源物与ｐｐ３８基因有极高的同源性。

马立克病病毒囊膜糖蛋白E基因的克隆及序列分析

用聚合酶链式反应 (PCR)技术 ,从中国广西分离的马立克氏病病毒 (MDV)N株和G2 株基因组DNA中 ,扩增出MDV糖蛋白E(gE)抗原基因片段的 1 5 0 0bp编码序列。将PCR扩增产物在KpnⅠ和HindⅢ位点克隆进 pUC1 8质粒载体中 ,以Dig标记的gEPCR产物作为探针做斑点杂交及酶切分析筛选到含MDVgE基因的目的重组质粒 pMNE、pMG2 E。通过酶切位点分析显示 ,两毒株的 gE基因内部酶切位点与MDV GA国际标准强毒株的酶切位点基本一致。对重组 pMNE、pMG2 E质粒进行部分序列测定 ,并用DNAStar软件分析 ,结果表明 :插入序列与发表的GA株gE基因序列具有高度同源性 ,gE基因为高度保守基因。