摘要：为了建立定量检测猪链球菌2型(SS2)粘附相关因子mRNA转录水平的荧光定量PCR方法,根据已报导的SS2粘附相关因子甘油醛-3-磷酸脱氢酶(GAPDH)、分选酶A(SrtA)、6-磷酸葡萄糖酸脱氢酶(6-PGD)及其管家基因aroA,用GenBank登录的核苷酸序列,设计特异性引物,提取SS2总RNA,经RT-PCR扩增和克隆了各粘附相关因子的核苷酸片段,以构建含有各自引物扩增序列的重组质粒,建立检测各粘附相关因子SYBR GreenⅠ荧光定量PCR方法。该方法起始模板数的对数与荧光信号达到所设定荧光阈值所经历的循环数(Ct)之间线性关系好,相关系数均达到0.995以上;扩增产物形成单一的特异性熔解峰;初始模板的检出下限达到了1μl 1.0×102拷贝数;组内变异系数小于2%,说明该方法特异性强、敏感性高、重复性好。

摘要：针对猪胸膜肺炎放线杆菌种特异性基因ApxⅣ和血清1、3、5、7型的特异Cps基因设计5对引物,通过扩增条件的优化,建立了猪胸膜肺炎放线杆菌及血清1、3、5、7型的五重PCR检测方法。特异性试验显示,对血清1~15型参考菌株均扩增出相应的预期目的条带,对6种引起猪发病的主要病原菌均未扩增出任何条带。敏感性试验表明,对各血清型细菌纯培物的敏感性皆为103 CFU/mL;对1、5型感染样品的敏感性为104 CFU/g,对3、7型感染样品的敏感性为103 CFU/g。可在4.5 h左右直接从病猪肺脏中得到检测结果。方法的建立为相关临床病例快速诊断及流行病学调查提供了有效的技术支持。

摘要：为了更好防治由出血性大肠杆菌O157∶H7引起的疾病,尝试研制基因工程疫苗,其中亚单位疫苗时具有很大优势。构建表达tir和stx1b的融合基因,将tir基因中间295个氨基酸残基(Tir295)与stx1b亚基基因72个氨基酸串联构建pGEX-stx2b-tir-stx1b重组质粒,将其转化于BL21(DE3),用IPTG进行诱导表达,经SDS-PAGE电泳检测,该融合蛋白获得了高效表达,目的蛋白表达量占菌体总蛋白含量的30%左右。重组蛋白纯化后皮下途径免疫小鼠,能够诱导高滴度(105)的IgG,鼻腔内途径免疫小鼠不仅能够诱导高滴度(104)的IgG,还能诱导高达102的IgA。二免后攻击50LD50的EHECO157∶H7,相对于对照组,免疫组粪便中排菌量明显降低、排菌时间明显缩短。结果表明:该融合蛋白免疫原性良好,并且由Tir、Stx2b和Stx1b三部分抗原组成,可刺激机体产生针对转位紧密素受体(Tir)和志贺毒素(Stx)的抗体,在EHECO157亚单位疫苗设计或单克隆抗体抗制备中具有重要价值。

摘要：建立用于从临床样品中检测EHEC O157:H7的二重PCR方法。根据GenBank登录EHEC O157:H7序列,通过对菌体和鞭毛抗原保守性核苷酸序列的比对和分析,分别设计编码O抗原rfbE基因和编码H抗原fliC基因各1对特异性引物,建立二重PCR检测方法,并以EHEC O157:H7纯培养和模拟制备的3种阳性样品为原材料,对方法的敏感性和特异性进行分析。运用成功建立的二重PCR,从带菌率最高的牛粪便中检测EHEC O157:H7,并进行菌株分离和鉴定。成功建立了rfbE与fliC的二重PCR方法,rfbE与fliC引物比例为2.5∶1,PCR循环参数中退火温度为56℃,扩增片段长度rfbE为812 bp,fliC为625 bp。检测阳性临床样品检测敏感性可以达到10 cfu/g。检测24株非EHEC O157:H7大肠杆菌和15株非大肠杆菌,只有EHECO157:H7能够扩增出特异性的rfbE条带,EHEC O157:H7和EPEC O55:H7能够扩增出fliC。只有EHEC O157:H7能够同时扩增出rfbE与fliC 2条目的条带。从63份牛粪便样品中分离到4株EHEC O157:H7:生化试验表明4株EHEC O157:H7具有典型EHECO157:H7的生化特性;药敏试验表明4株EHEC O157:H7具有较为广谱的耐药性;rfbE序列分析与GenBank序列同源性介于97.3%～99.2%之间,fliC序列与GenBank序列同源性介于97.6%～100%之间;4株EHEC O157:H7对Balb/c小鼠的致病性有差异,EHEC O157:H728#和EHEC O157:H738#致病性强,EHEC O157:H73#和EHEC O157:H717#较弱。以rfbE和fliC为目的基因成功建立了二重PCR,敏感性和特异性良好,可用于临床样品的检测,提高细菌分离率。

摘要：为建立检测PHoV的TaqMan荧光定量PCR方法,本研究根据PHoV的V P2基因序列设计引物和探针,以梯度稀释的含有V P2基因的重组质粒作为标准品,进行定量PCR反应。结果显示,该方法的检测灵敏度为10拷贝;而且该检测方法特异性较好,与猪的其他病毒核酸均无交叉反应;批内和批间的变异系数低于3.29%,表明该方法的重复性较好。对华东地区采集的225份临床样品进行检测,结果显示,PHoV的阳性率为14.2%。本研究建立的荧光定量PCR方法灵敏度高、特异性好,可以为PH oV的流行病学调查和发病机制等研究提供可靠的工具。

摘要：为研究猪博卡病毒VP2蛋白的功能及其在疫病诊断中的作用,对其基因进行了克隆和原核表达。根据猪博卡病毒基因组序列(GenBank登录号GU902967-GU902971)设计了1对引物,采用PCR方法扩增猪博卡病毒的VP2基因,并将其克隆到表达载体pET32a(+)中,构建重组质粒pET32a-VP2,经测序鉴定正确后,将其转化感受态细胞BL21(DE3),并进行IPTG诱导表达。结果表明,重组菌可表达分子量为49 000的融合蛋白,蛋白质表达量较高,且以可溶性形式存在于菌体中。表达产物经纯化后,目的蛋白纯度较好。Western blot结果显示,表达的VP2蛋白能与His抗体发生特异性免疫反应。说明该试验成功克隆了猪博卡病毒的VP2基因并进行了原核表达,为研究该蛋白的功能及建立血清学诊断方法奠定了基础。

摘要：[Objective] This study aimed to establish a real-time PCR method for de- tecting stx2 gene in Shiga toxin-producing E. coli （STEC）. [Method] According to the known STEC stx2 gene sequences published in GenBank, PCR primers and probes were designed based on the conserved region to construct recombinant plasmid as a positive template, thus optimizing the reaction conditions and establishing the real- time PCR method. [Result] A standard curve was established based on the opti- mized real-time PCR system, indicting a good linear correlation between the initial template concentration and Ct value, with the correlation coefficient F^e of above 0.995. The established method had a good specificity, without non-specific amplifica- tion for 10 non-STEC intestinal bacterial strains; the detection limit of initial template was 1.0x102 copies/μI, indicating a high sensitivity; furthermore, the coefficients of variation within and among batches were lower than 1% and 5% respectively, sug- gesting a good repeatability. [Conclusion] In this study, a real-time PCR method was successfully established for detecting STEC stx2 gene, which provided technical means for rapid detection of STEC in samples.

摘要：IL-1β和IL-18是重要的促炎症细胞因子,在介导机体炎症反应中起重要作用。为了建立在体外定量检测猪细胞因子IL-1β和IL-18 mRNA表达水平的SYBR GreenⅠ荧光定量PCR方法,依据GenBank中登录的猪细胞因子基因IL-1β、IL-18及管家基因β-actin核苷酸序列,设计特异性引物,经RT-PCR从3D4猪肺泡巨噬细胞系中克隆和扩增了上述3个因子核苷酸片段,构建含有各自引物扩增序列的重组质粒作为阳性模板,建立了检测IL-1β、IL-18及β-actin SYBR GREEⅠ荧光定量PCR方法。该方法起始模板数与Ct值之间线性关系好,相关系数达到0.990以上;特异性强,扩增产物形成单一的特异性熔解峰;敏感性高,初始模板的检出下限达到了1μl 1.0×102拷贝;重复性好,组内变异系数均小于4%。

摘要：[Objective] This study aimed to establish a method for quantitative detection of mRNA transcriptional level of SS2 adhesive related-factors of Streptococcus suis serotype 2 （SS2） by fluorescent quantitative PCR. []Vlethod] The gene fragments en- coding SS2 adhesive related-factors MRP, FBPS and CPS2J and a housekeeping gene aroA were amplified by reverse transcription PCR from the total RNA of SS2, cloned, and sequenced. The recombinant plasmids containing the target genes were constructed, and used as templates in Real-time PCR. [Result] Dynamic curves, stan- dard curves and melting curves of the adhesive related-factors and aroA were ob- tained by the optimized Real-time PCR system. The standard curves showed a good linear relationship between template copy number and circulation number, and the correlation coefficients （FF） of the standard curves were over 0.995. Also, these as- says were highly specific a^d there was single specific melting peak for every gene. Moreover, the assays were highly sensitive and had a detection limit of 1.0×102 copies in 1 μl of initial templates. Finally, it was highly repeatable and had a coeffi- cient of variation less than 2% for intra-assay. [Conclusion] This study will provide a way to reveal the adhesion mechanism of SS2 to different host cells at molecular level.

摘要：根据猪链球菌2型溶血素(SLY)的基因序列设计引物,以江苏分离株SS2-1的基因组为模板,扩增除信号肽序列外的溶血素成熟蛋白基因,并克隆到表达载体pET-32α(+)中,转化大肠杆菌BL21(DE3)。重组菌经1 mmol/L IPTG诱导,在37℃下4 h时表达产物(分子量约为7.2×104)达到高峰,表达量约占菌体总蛋白质的20%,表达产物在上清和包涵体中各占一半。将上清经镍柱亲和层析纯化,纯化蛋白质经Western blotting鉴定呈阳性,对绵羊红细胞、鸡红细胞的溶血效价分别为1.707×105HU/mg、4.267×104HU/mg,并可引起HEp-2和Vero细胞的颗粒增多、圆缩和脱落。纯化蛋白质对BALB/c小鼠的免疫保护率为83.3%(5/6)。这为进一步研究SLY致病机理和研制猪链球菌新型疫苗奠定了基础。