共查询到20条相似文献,搜索用时 62 毫秒
1.
一、DNA疫苗的免疫机理
DNA疫苗(DNAvaccine)又称基因疫苗、核酸疫苗,由病原抗原编码基因及质粒载体两部分组成。抗原基因可以是单个基因或完整的一组基因,也可以是编码抗原决定簇的一段核苷酸序列,质粒载体可在真核细胞中表达外源基因。DNA疫苗是将编码目的抗原蛋白基因序列的真核质粒,经各种基因转移途径导入机体细胞,通过宿主细胞转录、翻译、表达出相应的抗原蛋白, 相似文献
2.
一、DNA疫苗的免疫机理
DNA疫苗(DNA vaccine)又称基因疫苗、核酸疫苗,由病原抗原编码基因及质粒载体两部分组成.抗原基因可以是单个基因或完整的一组基因,也可以是编码抗原决定簇的一段核苷酸序列,质粒载体可在真核细胞中表达外源基因.DNA疫苗是将编码目的抗原蛋白基因序列的真核质粒,经各种基因转移途径导入机体细胞,通过宿主细胞转录、翻译、表达出相应的抗原蛋白,诱导宿主产生针对该抗原蛋白的保护性免疫应答,从而达到免疫的目的. 相似文献
3.
4.
核酸疫苗的研究与应用 总被引:1,自引:0,他引:1
核酸疫苗(nucleicacidvaccine)是指将含有编码某种抗原蛋白的外源基因(DNA或RNA)序列质粒载体作为疫苗,直接导入到动物细胞内,通过宿主细胞的表达系统合成抗原蛋白,诱导宿主产生对该抗原蛋白的免疫应答,以达到预防和治疗疾病的目的。核酸疫苗又称为基因疫苗或裸DNA疫苗,核酸疫苗包括DNA疫苗和RNA疫苗。这种免疫称为核酸免疫、基因免疫、DNA介导的免疫以及遗传免疫等。核酸疫苗与传统疫苗相比有许多优势。1核酸疫苗的研究历史核酸疫苗是由基因治疗发展而来的,1990年Wolff等发现,在小鼠肌肉组织内直接注射质粒DNA后,质粒及其携带的外… 相似文献
5.
6.
核酸免疫是利用重组DNA技术将保护性抗原蛋白基因克隆到真核表达载体,并将其直接导入体内,使抗原蛋白经过内源性表达递呈给免疫系统,诱发机体产生特异性的体液免疫和细胞免疫反应。核酸免疫也称DNA免疫或基因免疫。用于免疫注射的质粒DNA称为核酸疫苗(nucleicacidvaccine)或DNA疫苗(DNAvaccine)。核酸疫苗不同于传统的弱毒苗、灭活疫苗及蛋白亚单位苗,它是带有特异抗原基因的真核表达质粒。1 核酸免疫的发展核酸免疫是随着现代分子生物学和免疫学的发展而产生的。70年代末,Israel等将纯化的多瘤病毒DNA直接注射小鼠,证实裸DNA可被… 相似文献
7.
动物预防用DNA疫苗又称核酸疫苗或基因疫苗,是编码免疫原或与免疫原相关的真核表达质粒DNA(有时也可是RNA),它可经一定途径进入动物体内,被动物宿主细胞摄取后能转录和翻译表达出抗原蛋白,此抗原蛋白能够刺激机体产生非特异性和特异性两种免疫应答反应,从而起到免疫保护作用。 相似文献
8.
9.
10.
11.
12.
13.
本文概述了猪的毛色类型、猪的毛色遗传模式,着重综述了猪毛色基因分子基础的研究进展,指出存在问题并就未来发展方向做了思考。 相似文献
14.
魏静 《四川畜牧兽医学院学报》2009,(4):28-32
在现代法律秩序中,商会自治规范是制定法的基础和必要的补充,甚至在某些方面替代了制定法;商会自治规范主要包括商会组织规范、行为规范、惩罚规范以及争端解决规范等;其效力仅及于其内部成员;商会自治规范和制定法之间存在冲突,但也存在整合的基础。 相似文献
15.
Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF
Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo. 相似文献
16.
17.
以国际标准强毒R株人工感染非免疫产蛋鸡,定时扑杀,分别从鼻窦、眶下孔、气管、肺、气囊、卵巢和输卵管分离MG,并收集感染鸡所产蛋分离MG。结果表明,人工感染48小时后上、下呼吸道及肺已被全面感染,96小时气囊已被感染,120小时输卵管已能分离到MG,卵巢始终分离不到MG。人工感染鸡自144小时便能在其所产蛋中分离出MG。药物治疗能在72小时内消除感染,油乳剂苗则需24天后逐渐降低蛋内MG分离率,药物卵内注射、种蛋药浴、高温处理均能杀死卵内MG,但以研制的种蛋浸泡剂药浴效果为最好。 相似文献
18.
乳酸杆菌作为益生菌广泛用于人和动物.本文综述了乳酸杆菌改善宿主健康的机制.乳酸杆菌可通过产生抗菌物质如乳酸、过氧化氢、细菌素,或者通过竞争营养或肠道黏附位点来抑制致病菌;通过诱导黏附素的分泌或阻止细胞凋亡而增强肠道的屏障功能,从而保护肠道.文章重点讨论了乳酸杆菌表面成分(表面蛋白、脂磷壁酸和肽聚糖)与肠道受体(C型凝集素受体、Toll样受体和Nod样受体),阐述了他们结合后启动免疫调节信号,调控肠道免疫功能以发挥改善健康作用的机制. 相似文献
19.
REASONS FOR PERFORMING STUDY: Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation. OBJECTIVE: To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted. METHODS: For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS. RESULTS: Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined. CONCLUSIONS: Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air. 相似文献