重组牛皮蝇素A蛋白的免疫试验

用由毕赤酵母表达的皮蝇素A（Hypdermin A，HA）蛋白分别免疫新西兰大白兔和牦牛，了解该蛋白免疫效果。用两种不同分子量的重组HA蛋白分别免疫新西兰大白兔1次和2次，ELISA测其抗体消长规律。结果表明，3周后抗体水平达到峰值，后缓慢下降。50KD蛋白免疫效果较30KD蛋白好，差异非常显著（P〈0．01）。用其中50KD的重组HA蛋白分别在7月和9月免疫自然感染牛皮蝇蛆病牦牛，观察感染率和感染强度，ELISA测其抗体消长规律。结果表明，7月免疫组与9月免疫组感染率分别为83．3％和36．3％（对照组为55．5％）；平均感染强度分别为6．5和4．2（对照组为13．0），差异不显著（P〉0．05）。免疫后，抗体水平上升，3个月后缓慢下降。9月免疫组免疫效果较7月免疫组好，三组抗体水平差异非常显著（P〈0．01）。上述研究结果为防治牛皮蝇蛆病疫苗的深入研究和实践运用提供了参考依据。     

牛皮蝇HA抗原基因转化紫花苜蓿的研究

以“甘农1号”紫花苜蓿(Medicago sativa)7 d苗龄子叶和下胚轴为受体材料,建立了高效的苜蓿再生体系和遗传转化体系,筛选出MS+2,4 D 2.0 mg/L+6 BA 0.5 mg/L和MS+6 BA 0.5 mg/L+NAA 0.03 mg/L+GA3 2.0 mg/L为苜蓿子叶愈伤组织诱导和分化的适宜培养基;探讨了农杆菌浓度OD600约0.5、感染时间8~10 min、共培养时间2 d为适宜的转化条件。采用农杆菌介导法将Hyperdomin A（HA）基因导入紫花苜蓿,经PCR检测和Southern分子杂交分析,结果表明HA基因已经整合到苜蓿基因组中,可为牛皮蝇蛆病可食性疫苗的研究提供理论基础。     

牛皮蝇Hypodermin B 基因的克隆及原核表达载体构建

参照牛皮蝇Hypodermin B(HB)基因的核苷酸序列,设计一对引物,以牛皮蝇总RNA为模板利用RT—PCR扩增牛皮蝇HB基因,并对扩增基因进行克隆测序。序列分析表明,克隆的牛皮蝇HA基因与GenBank中已经登录的核苷酸和氨基酸序列的同源性分别为97．2％和99．3％。同时,将该基因与原核表达载体．PGEX-4T-1连接,构建并获得阳性重组表达载体。     

牛皮蝇幼虫抗原基因原核表达条件的优化

分别对构建的3种牛皮蝇幼虫抗原(Hypodermin A,B,C)基因重组表达菌BL21(pETHA)、BL21(pETHB)、BL21(pETHC)在不同的诱导时间、诱导剂浓度和诱导温度等条件下的表达情况进行了研究.结果表明,重组表达菌BL21(pETHA)、BL21(pETHB)、BL21(pETHC)最佳诱导时间...     

皮蝇素A基因的克隆与序列分析

首先提取采自甘肃玛曲的皮蝇一期幼虫的总RNA,合成cDNA,根据设计的特异引物,利用PCR技术扩增出Hypodermin A(HA)基因片段,将此片段与PGEM-T Easy载体连接,构建克隆载体PGEM-HA,转化大肠杆菌JM109,筛选阳性克隆,进行测序与分析。结果表明,扩增的HA基因长678bp,编码229氨基酸。克隆到的基因序列与NCBI GenBank上登陆的皮蝇HA基因序列核甘酸同源性为96.6%,推导氨基酸同源性达97.8%。该基因的成功克隆为其进一步表达打下了坚实的基础。     

纹皮蝇Hypodermin C基因原核表达及间接ELISA检测方法的建立

为建立牛皮蝇蛆病的抗体检测方法,本研究从纹皮蝇I期幼虫中提取总RNA,采用RT-PCR扩增了Hypodermin C(HC)基因.将该基因片段插入到原核表达载体pET-30a(+)中进行原核表达.获得了31ku以包涵体形式表达的重组HC蛋白.Western blot结果表明表达产物能够与阳性牛血清IgG特异性结合,具有良好的抗原活性.以纯化的重组HC作为包被抗原建立了牛皮蝇蛆病间接ELISA诊断方法,实验确定抗原最佳包被浓度为15.63 μg/mL,血清最佳稀释度为1:80,阳性标准判定为待检血清OD值＞0.256.所建立的诊断方法具有较好的特异性、敏感性和可重复性.应用该检测方法对230份临床血清进行检测,阳性率为20.6％.研究结果表明该间接ELISA方法是一种有效的牛皮蝇蛆病血清学检测方法.     

皮蝇素A基因的克隆及其毕赤酵母表达载体的构建

提取采自甘肃玛曲皮蝇一期幼虫的总RNA,合成cDNA,根据设计的特异引物,利用PCR技术扩增出皮蝇素A(Hypodermin A,HA)基因片段,用Xho Ⅰ、Xba Ⅰ消化,将消化后的目的基因HA纯化并回收,与经同样的酶消化后并纯化回收的裁体pPICZa连接并转化,获得重组表达质粒pPICZa-HA,经PCR、酶切、测序表明,目的基因插入位置、方向和阅读框正确.     

纹皮蝇HypoderminC基因真核表达质粒构建及小鼠免疫试验

根据GenBank发表的Hypodermin C(HC)基因序列设计引物,以原核表达载体pET-HC为模板,PCR扩增HC基因,将克隆基因插入到真核表达载体pVAX1中,构建重组真核表达质粒pVAX1-HC。将重组质粒pVAX1-HC转染小鼠胎儿成纤维细胞,以间接免疫荧光法检测HC基因在细胞中表达。用真核表达质粒pVAX1-HC经双侧胫前肌注射昆明小鼠,对小鼠进行体液免疫和细胞免疫研究。结果表明,小鼠血清抗体水平和淋巴细胞增殖水平明显高于非免疫对照组。本研究成功构建了真核表达质粒pVAX1-HC,为纹皮蝇核酸疫苗研发奠定了基础。     

皮蝇Hypodermin A基因的克隆及表达质粒构建

参照牛皮蝇HypoderminA(HA)基因的核苷酸序列,设计一对引物,以皮蝇总RNA为模板进行RT--PCR扩增牛皮蝇HA基因,将扩增基因进行克隆测序。序列分析表明,所克隆获得的基因与GenBank中已经登录的核苷酸和氨基酸的同源性分别为97.2%和99.3%。同时,将该基因与表达载体PGEX-4T-1连接,构建并获得阳性重组表达载体。     

Impact of previous infestation on dynamics of circulating hypodermin C in cattle artificially infested with Hypoderma lineatum (Diptera: Oestridae)

Four groups of cattle were artificially infested with 50 first instar Hypoderma lineatum after either a primary natural infestation or in the absence of a primary infestation. In two groups the primary infestation had been terminated by the application of either an organophosphate insecticide or a macrocyclic lactone parasiticide. Circulating hypodermin C and specific antibodies were measured for 40 weeks after the artificial infestation. Stage specific mortality of the larvae was also monitored. Previously uninfested cattle exhibited typical antibody and antigen profiles during the infestations. Antibodies were first detected on Week 7 p.i., they rose to maximum values between Weeks 24 and 25, then declined as larvae reached the back. A second peak occurred at Week 32 and antibody remained more less constant thereafter. Previously infested groups exhibited a dramatic anamnestic response by Week 3 p.i. with antibody levels peaking at Week 8. A second peak was noted between Weeks 24 and 26 p.i. after which antibody levels declined and then remained relatively stable. The dynamics of circulating hypodermin C in the previously infested cattle resembled those in the previously uninfested cattle. Mortality of first instars did not differ among the four groups. Similarly mortality of second and third instars, in the warble, did not differ although there was a tendency for higher mortality in the previously infested, untreated group. These results reinforce previous work demonstrating the development of a significant immune response during the primary infestation that is reflected in the rapid and substantial production of antibodies upon re-infestation. It is significant that a challenge model using subcutaneous injection of newly hatched first instars avoids host immune responses in the skin that result in substantial larval mortality. The current data also support the concept that migrating first instars induce significant reduction in host immune response. There is a peak of antibody production as antigen levels peak during first instar migration to the back. As larvae molt to the second instar and antigen production ceases there is a persistence of antibody which suggests release of the immune response from the suppression induced by the first instar secretory antigens.