弓形虫酵母双杂交cDNA文库构建及与Rop38相互作用蛋白的筛选

为筛选与弓形虫棒状体蛋白38基因(Rop38)相互作用的宿主细胞蛋白,本研究利用MatchmakerTM Gold酵母双杂交系统,构建了人成纤维细胞(HFF)和人T细胞(CEM.NKR)的c DNA文库,以构建的p GBKT7-Rop38作为诱饵质粒,采用PEG/Li Ac法转化酵母菌株Y2H,利用表型筛选法检测Rop38的自激活作用并进行酵母双杂交筛选。结果表明,诱饵蛋白在酵母双杂交系统中无毒性和自激活作用,而且通过酵母双杂交筛选共获得29个与Rop38蛋白相互作用的宿主蛋白,其中HFF文库筛选到20个蛋白,CEM.NKR文库筛选到11个蛋白。本实验为进一步研究Rop38调节宿主细胞基因表达的信号通路奠定了基础。     

弓形虫细胞核因子3基因的克隆及序列分析

为预测弓形虫细胞核因子3(TgNF3)基因作为抗弓形虫疫苗候选抗原的可能性,本试验以弓形虫RH株的总RNA为模板,应用逆转录-聚合酶链式反应(RT-PCR)扩增TgNF3基因并连接至pMD18-T载体。筛选阳性克隆后,测序鉴定。将测序结果正确的核苷酸序列翻译成氨基酸序列,运用生物信息学软件分析TgNF3蛋白的结构,预测抗原表位。结果显示,TgNF3基因长约950bp。TgNF3蛋白中包含1个跨膜结构域,9个α-螺旋区,4个β-折叠区,8个亲水区域和10个柔性区域,并预测含有9个线性B细胞抗原表位。结果表明,TgNF3蛋白可能具有良好的免疫原性,为研制以TgNF3为抗原的弓形虫亚单位疫苗及表位疫苗奠定了基础。     

Winter Scours' in sheep — An oibsolete term

We recently published a paper⁽¹⁾ documenting the success of head-only electrical stunning in red deer (Cervus elaphus). This work has now been extended to fallow deer (Dama dama) to determine whether there are differences between this species and red deer in terms of behavioural responses and effectiveness of electrical stunning.     

Latitudinal variability in the seroprevalence of antibodies against Toxoplasma gondii in non-migrant and Arctic migratory geese

Toxoplasma gondii is an intracellular coccidian parasite found worldwide and is known to infect virtually all warm-blooded animals. It requires a cat (family Felidae) to complete its full life cycle. Despite the absence of wild felids on the Arctic archipelago of Svalbard, T. gondii has been found in resident predators such as the arctic fox and polar bear. It has therefore been suggested that T. gondii may enter this ecosystem via migratory birds. The objective of this study was to identify locations where goose populations may become infected with T. gondii, and to investigate the dynamics of T. gondii specific antibodies. Single blood samples of both adults and juveniles were collected from selected goose species (Anser anser, A. brachyrhynchus, Branta canadensis, B. leucopsis) at Arctic brood-rearing areas in Russia and on Svalbard, and temperate wintering grounds in the Netherlands and Denmark (migratory populations) as well as temperate brood-rearing grounds (the Netherlands, non-migratory populations). A modified agglutination test was used on serum, for detection of antibodies against T. gondii. Occasional repeated annual sampling of individual adults was performed to determine the antibody dynamics. Adults were found seropositive at all locations (Arctic and temperate, brood-rearing and wintering grounds) with low seroprevalence in brood-rearing birds on temperate grounds. As no juvenile geese were found seropositive at any brood-rearing location, but nine month old geese were found seropositive during spring migration we conclude that geese, irrespective of species and migration, encounter T. gondii infection in wintering areas. In re-sampled birds on Svalbard significant seroreversion was observed, with 42% of seropositive adults showing no detectable antibodies after 12 months, while the proportion of seroconversion was only 3%. Modelled variation of seroprevalence with field data on antibody longevity and parasite transmission suggests seroprevalence of a population within a range of 5.2–19.9%, in line with measured values. The high occurrence of seroreversion compared to the low occurrence of seroconversion hampers analysis of species- or site-specific patterns, but explains the absence of an increase in seroprevalence with age and the observed variation in antibody titre. These findings imply that even though infection rate is low, adults introduce T. gondii to the high Arctic ecosystem following infection in temperate regions.     

刚地弓形虫Rop18基因的原核表达及鉴定

利用PCR技术从弓形虫RH株基因组中扩增出Rop18基因片段,克隆入pET-30a载体,将重组质粒转化入大肠杆菌Top10中,经酶切鉴定获得阳性重组质粒并对其进行测序。测序结果与参考序列(登录号:JX045329.1)比对发现,核苷酸同源性为99.6%。将阳性重组质粒转化入大肠杆菌BL21中,表达产物经SDS-PAGE检测结果显示,Rop18基因在大肠杆菌中成功表达;融合蛋白的分子质量在66.2 ku左右,Western blotting显示其能被兔抗弓形虫免疫血清识别。结果表明,弓形虫RH株Rop18基因可以在原核表达系统中高效表达,该重组蛋白具有免疫原性,有望作为弓形虫疫苗候选抗原。     

刚地弓形虫微线体蛋白3的研究进展

微线体蛋白3(MIC3)是刚地弓形虫生活史各个时期均能表达的分泌蛋白,具有较强的免疫反应性,在弓形虫对宿主细胞的识别、黏附及入侵过程中发挥重要作用。深入研究弓形虫MIC3有助于研制弓形虫病诊断制剂及疫苗以防制弓形虫病。文章综述了近年来关于MIC3的分子生物学特征、相关疫苗及其用于弓形虫病诊断方面的研究进展。     

弓形虫PCR检测试剂盒的组装和初步应用

研制弓形虫PCR检测试剂盒,观察临床应用效果。根据GenBank公布的弓形虫MIC3基因序列,设计合成1对特异性引物,对PCR反应条件进行优化,分别对试剂盒的特异性、敏感性、重复性、稳定性和保存期进行研究,之后进行临床试验。该诊断试剂盒能扩增出弓形虫特异性基因MIC3片段,与猪球虫、贾第虫、猪旋毛虫和隐孢子虫无交叉反应;该检测方法最低能够检测到10个弓形虫速殖子的DNA,不同批次的试剂盒对同一样品检测和同一批次对不同样品检测,有较高的重复性和稳定性,且常温下可保存1年以上,临床应用效果显著。该检测试剂盒对弓形虫病早期诊断、流行病学调查和卫生检疫提供了检测手段。     

利用环媒恒温基因扩增法检测生猪刚地弓形虫

基于已公布的刚地弓形虫Sag2基因序列设计了1套特异引物,经过条件优化,成功建立了针对刚地弓形虫(简称弓形虫)的环媒恒温基因扩增检测法.根据扩增弓形虫和其他几种病原生物的效果对该方法进行评估.结果表明,该方法只检出致病性弓形虫,特异性良好;检测最低速殖子浓度为4个/μL.对长沙、株洲、湘潭三地生猪血样检测的结果是仔猪、成猪和种母猪弓形虫感染率分别为6.45%、7.69%和15.38%.     

刚地弓形虫GRA25基因的克隆及序列分析

本研究旨在对来源于不同宿主和地理分布的22株弓形虫的GRA25基因进行PCR扩增并测序,对获得的GRA25基因序列进行比对,利用MP和ML两种方法对不同分离株的GRA25基因构建系统进化树。利用生物信息学软件将弓形虫RH株的GRA25基因翻译成氨基酸序列,对其编码蛋白的生物学特征进行分析。结果显示,弓形虫GRA25基因序列有2种长度,分别为939和948 bp。序列比对结果显示,GRA25基因在不同虫株间有82个核苷酸变异位点,变异率为0~4.4%。进化分析结果显示,用GRA25基因不能区分弓形虫基因Ⅰ型和Ⅱ型虫株。生物信息学分析预测弓形虫GRA25蛋白含有7个亲水区域,10个α-螺旋,3个β-折叠,8个无规则卷曲和8个潜在的线性B淋巴细胞抗原表位。本研究结果表明,GRA25基因不能作为标记分子区分不同基因型的弓形虫虫株,但可能作为疫苗候选分子研制新型抗弓形虫基因疫苗或表位肽疫苗。     

新孢子虫与弓形虫交叉抗原AMA1基因重组腺病毒的构建及免疫应答分析

为构建新孢子虫和弓形虫AMA1基因重组腺病毒,并分析其免疫原性,本试验根据新孢子虫和弓形虫AMA1基因序列的开放阅读框,设计新孢子虫和弓形虫交叉抗原AMA1基因通用引物,构建重组克隆质粒pMD18T-NcAMA1、pMD18T-TgAMA1及重组腺病毒穿梭质粒ADV4-Nc/TgAMA1,将ADV4-Nc/TgAMA1和骨架质粒pacAd5线性化后共转染293T细胞,包装Ad5-Nc/TgAMA1重组腺病毒,测定病毒滴度后,收集病毒液接种BALB/c小鼠,间接ELISA检测小鼠血清IgG抗体水平。结果显示,Nc/TgAMA1在Ad5-Nc/TgAMA1重组腺病毒中获得表达,测定Ad5-Nc/TgAMA1重组腺病毒滴度为10⁹PFU/mL,接种BALB/c小鼠后,Ad5-Nc/TgAMA1接种组IgG抗体水平明显高于pVAX1-Nc/TgAMA1质粒组和PBS对照组。结果表明,构建的Ad5-Nc/TgAMA1重组腺病毒能诱导小鼠产生特异性体液免疫应答。本试验为新孢子虫和弓形虫交叉抗原AMA1基因重组腺病毒载体疫苗的研制奠定了基础。