基因疫苗及其在猪传染病中的应用

基因疫苗被视为“第三次疫苗革命”，是目前疫苗领域的研究热点。综述了基因疫苗的发现、基因疫苗的免疫学机理、基因疫苗的优越性以及其在猪传染病中的应用，并提出了基因疫苗在应用过程中存在的问题，从而为畜禽传染病的防治提供新的思路。     

植物基因工程疫苗在畜牧业上的应用与发展前景

利用基因工程技术构建植物生物反应器,生产畜禽的植物基因工程疫苗是新兴的研究领域,和其他疫苗相比,具有廉价、安全、有效等优点。在最近的研究中,越来越多的抗原蛋白在植物中得到了表达。应用植物基因工程生产畜禽疫苗对预防集约化饲养动物传染病的发生和流行具有重要意义。本文就植物基因工程疫苗的特点及其在畜禽业上的应用和发展前景进行了综述。     

动物疫苗现状和研究展望

畜禽传染病的控制和消灭对保证养殖业的健康发展至关重要。传染病控制的原理是针对引起流行的三个环节，即消灭传染源、切断传播途径和保护易感群体。本文的主题是讲疫苗。疫苗免疫的作用主要是保护易感群体。显然，要有效控制乃至消灭传染病，单靠疫苗是不够的，因为没有解决传染源和传播途径的问题。我国在应用疫苗控制畜禽疫病中存在认识误区，即过分地依赖疫苗，这种思想存在于相当一部分决策的领导人中，也存在于一些经营者和技术人员中。我们只有正确认识疫苗在控制乃至消灭畜禽传染病中的作用，才能把握疫苗研究的方向，才能正确使用疫苗。     

基因疫苗在畜禽传染病中的作用

基因疫苗亦称DNA疫苗,是将编码某种蛋白质抗原的真核重组表达载体直接注射机体,在宿主细胞中表达外源基因,诱导特异性的体液免疫应答和细胞免疫应答,达到预防和治疗疾病的目的。基因疫苗在病毒感染性疾病中有广阔的应用前景,已成为疫苗研究领域的热点之一。基因疫苗被称为第三次疫苗革命。基因免疫已在畜禽传染病,如病毒性疾病、细菌性疾病、寄生虫免疫、抗肿瘤免疫、预防变态反应中发挥了巨大的作用。     

如何充分发挥疫苗的作用及疫苗的发展趋势

畜禽疫苗是控制和消灭畜禽传染病的有力武器，随着免疫学．生物化学、分子生物学．分子遗传学等学科的发展，畜禽疫苗的研究日新月异．种类越来越多，技术水平也越来越高．应用范围也越来越广泛，在畜牧养殖业中所起的作用也将越来越大。为使广大养殖业技术人员全面了解畜禽疫苗的作用，更好地控制畜禽传染病，综合我国畜禽疫苗的研究情况及发展动态论述如下。     

浅析畜禽免疫水平低下的原因

近年来，畜禽的疫病控制越来越受到重视。畜禽疫苗是控制和扑灭畜禽传染病的有力措施。但在实际应用中免疫效果并不十分理想，我们常遇到畜禽接种了某种疫苗后，仍发生该病，根据笔者在动物疫病诊断工作中的经验，现就当前畜禽免疫水平低下的原因作简要浅析。     

畜禽疫苗研究展望

畜禽传染病的控制和消灭对保证养殖业的健康发展至关重要。传染病控制的原理是针对引起流行的三个环节采取相应的措施，即消灭传染病，切断传播途径和保护易感群体。本文的主题是讲疫苗。疫苗免疫的作用主要是保护易感群体。显然要有效控制乃至消灭传染病，单靠疫苗是不够的，因为没有解决传染源和传播途径的问题。我国在应用疫苗控制畜禽疫     

DNA疫苗研究进展

DNA疫苗是一种新型的疫苗，能够诱发体液免疫和细胞免疫。本文简单介绍了DNA疫苗作用机理，产生的免疫反应，在畜禽传染病中的应用及免疫影响因素，并分析了DNA疫苗的安全问题及其应用前景。     

生物技术在畜牧业发展中的应用

本文阐述了目前全球农业生产所面临的各种难题,着重探讨了生物技术在畜禽品种改良、畜禽产品在生化制药、PCR在畜禽疫病诊断、基因疫苗在畜禽传染病中的广泛应用,21世纪农业将是农业生物技术广泛应用的时代。     

畜禽疫苗专供秩序的建立

畜禽疫苗的使用在畜牧业生产中占有重要位置．从五十年代初开始，我省使用牛瘟、猪瘟、猪丹毒、猪肺疫等10多种疫苗，消灭了牛瘟并控制了家畜多种传染病的发生．六十年代，全省实行了疫苗计划管理，开展对畜禽主要传染病大面积的预防接种工作．随着社会的发展，科学的进步，畜禽疫苗的品种和使用数量不断增加，到1997年全省使用各种疫苗50余种，其中预防接种猪瘟疫苗9239万头次、鸡新城疫31794万羽次．疫苗的广泛应用，有效控制了畜禽疫病的发生，每年为农民减少直接经济损失数亿元，经济和社会效益十分显著，保护和促进了我省畜牧业生产的…     

动物核酸疫苗的研究现状及发展前景

核酸疫苗是近年来备受人们关注的一种新型疫苗。核酸疫苗以其特有的可诱导机体产生全面的免疫应答,对不同亚型的病原体具有交叉防御作用,以及安全、可靠、生产方便等优点被称之为“疫苗的第三次革命”。核酸疫苗由编码能引起保护性免疫反应的病原体抗原的基因片段和载体构建而成,包括DNA疫苗和RNA疫苗,目前研究较多的是DNA疫苗。DNA疫苗是指含有编码抗原基因的真核表达质粒DNA,经直接接种体内后,可被体细胞摄取,并转录、翻译、表达出相应的抗原,然后通过不同途径刺激机体产生针对此种抗原的应答。作者简单介绍了动物核酸疫苗的特点、免疫机制、免疫影响因素及在畜禽传染病中的应用,此外还分析了核酸疫苗的发展前景等问题,从而为核酸疫苗的发展提供了新思路和新途径。     

Strategies and hurdles using DNA vaccines to fish

DNA vaccinations against fish viral diseases as IHNV at commercial level in Canada against VHSV at experimental level are both success stories. DNA vaccination strategies against many other viral diseases have, however, not yet yielded sufficient results in terms of protection. There is an obvious need to combat many other viral diseases within aquaculture where inactivated vaccines fail. There are many explanations to why DNA vaccine strategies against other viral diseases fail to induce protective immune responses in fish. These obstacles include: 1) too low immunogenicity of the transgene, 2) too low expression of the transgene that is supposed to induce protection, 3) suboptimal immune responses, and 4) too high degradation rate of the delivered plasmid DNA. There are also uncertainties with regard distribution and degradation of DNA vaccines that may have implications for safety and regulatory requirements that need to be clarified. By combining plasmid DNA with different kind of adjuvants one can increase the immunogenicity of the transgene antigen – and perhaps increase the vaccine efficacy. By using molecular adjuvants with or without in combination with targeting assemblies one may expect different responses compared with naked DNA. This includes targeting of DNA vaccines to antigen presenting cells as a central factor in improving their potencies and efficacies by means of encapsulating the DNA vaccine in certain carriers systems that may increase transgene and MHC expression. This review will focus on DNA vaccine delivery, by the use of biodegradable PLGA particles as vehicles for plasmid DNA mainly in fish.     

Powder and particle-mediated approaches for delivery of DNA and protein vaccines into the epidermis

The epidermis of the skin is both a sensitive immune organ and a practical target site for vaccine administration. However, administration of vaccines into the epidermis is difficult to achieve using conventional vaccine delivery methods employing a needle and syringe. A needle-free vaccine delivery system has been developed that efficiently delivers powdered or particulate DNA and protein vaccines into the epidermal tissue. The delivery system can be used to directly transfect antigen presenting cells (APCs) by formulating DNA or protein vaccines onto gold particles (particle-mediated immunization). Antigen can be directly presented to the immune system by the transfected APCs. Antigen can also be expressed and secreted by transfected keratinocytes and picked up by resident APCs through the exogenous antigen presentation pathway. Alternatively, protein antigens can be formulated into a powder and delivered into the extracellular environment where they are picked up by APCs (epidermal powder immunization). Using any of these formulations, epidermal immunization offers the advantage of efficiently delivering vaccines into the APC-rich epidermis. Recent studies demonstrate that epidermal vaccine delivery induces humoral, cellular, and protective immune responses against infectious diseases in both laboratory animals and man.     

寄生虫DNA疫苗研究进展

寄生虫病带来了相当大的社会经济影响,人畜共患寄生虫给人们带来巨大的疾病负担,并给养殖业造成严重的经济损失。因此,寄生虫病的防治是人们迫切需要研究的课题。寄生虫存在很多形式的免疫逃避机制,灭活疫苗、减毒活疫苗、亚单位疫苗等未达到理想的预防寄生虫病的效果,很多研究表明DNA疫苗有望成为预防和治疗寄生虫病的有效方法。DNA疫苗是一种新型疫苗,可同时诱导机体产生持久的体液免疫和细胞免疫,通过在宿主内表达外源蛋白来提供保护性免疫。DNA疫苗与其他亚单位疫苗不同的是,免疫原由摄取抗原编码DNA的细胞在宿主内合成。体内蛋白质的合成也能进行抗原加工、修饰并递呈到宿主的免疫系统中,类似于自然感染的方式。笔者就DNA疫苗免疫机制、设计原则、免疫途径、优缺点及近几年寄生虫DNA疫苗的研究进展进行综述,以期为寄生虫DNA疫苗的开发提供理论参考。     

Vaccination of chickens with a chimeric DNA vaccine encoding Eimeria tenella TA4 and chicken IL-2 induces protective immunity against coccidiosis

A fusion DNA vaccine co-expressed Eimeria tenella TA4 and chicken IL-2 (chIL-2) was constructed and its efficacy against E. tenella challenge was observed. TA4 gene of E. tenella and chIL-2 gene were cloned into expression vector pcDNA3.1 and pcDNA4.0c in different forms, producing vaccines pcDNA3.1-TA4-IL-2, pcDNA3.1-TA4 and pcDNA4.0c-IL-2. The expression of aim genes in vivo was detected by RT-PCR and western blot. Animal experiment was carried out to evaluate the immune efficacy of the vaccines. Results indicated these DNA vaccines were successfully constructed and the antigen genes could be expressed effectively in vivo. The animal experimental results showed that DNA vaccines could obviously alleviate cecal lesions, body weight loss and increase oocyst decrease ratio. The ACI of pcDNA3.0-TA4-IL-2 group was 192, higher than that of pcDNA3.1-TA4 group. The results suggested that TA4 was an effective candidate antigen for vaccine and co-expression of cytokine with antigen was an alternative method to enhance DNA vaccine immunity.     

Improved immunogenicity of DNA vaccination with mycobacterial HSP65 against bovine tuberculosis by protein boosting

A scientific review for the government of the United Kingdom has recommended that the development of a cattle vaccine against bovine tuberculosis holds the best prospects to control this disease in the national herd. As BCG vaccination of cattle results in variable degrees of protection, novel vaccine strategies that could replace or supplement BCG are required. In this study, the mycobacterial antigen HSP65 was used to determine whether priming cattle with a plasmid DNA vaccine and subsequently boosting with the recombinant protein in adjuvant (heterologous prime-boost approach) would result in improved and more homogenous immune responses over immunising with plasmid DNA or protein in adjuvant alone. The results demonstrated that strong, and compared to protein or DNA vaccination protocols alone, more homogenous, cellular immune responses were induced in cattle vaccinated with the prime-boost regimen. In addition, DNA prime-protein boost vaccination as well as protein vaccination resulted in stronger humoral immune responses with a balanced IgG profile compared to DNA vaccination alone. Importantly, none of the vaccination protocols sensitised cattle to the intradermal tuberculin test suggesting that TB subunit vaccines can be designed to allow the continued use of the tuberculin test to discriminate between vaccinated cattle and those infected with Mycobacterium bovis.     

Immunogenic and protective effects of a DNA vaccine for Mycobacterium marinum in fish

Mycobacteriosis, caused by numerous Mycobacterium spp., can be a devastating disease of both wild and cultured fishes. As no efficacious treatment exists, a vaccine against fish mycobacteriosis is essential for prevention and control of this disease. Thus, a DNA vaccine was constructed using the Mycobacterium marinum Ag85A gene that encodes one of the major secreted fibronectin-binding proteins of Mycobacterium spp., which was isolated and then subcloned into a commercially available eukaryotic expression vector. Juvenile hybrid striped bass (Morone saxatilis x M. chrysops), a species known to be particularly susceptible to this disease, were immunized by i.m. and i.p. injection with the resulting construct and as a result produced specific immune responses towards the Ag85A. Increasing concentrations of humoral antibodies to the Ag85A antigen were generated in all DNA vaccine groups, while macrophage phagocytosis and respiratory burst functions failed to exhibit upregulation after vaccination. In addition, fish receiving the DNA vaccine developed a protective response to a live M. marinum challenge 90 days post-inoculation, as demonstrated by increased survival of vaccinated fish over control fish and by reduced splenic bacterial counts in vaccinated fish. Furthermore, humoral immune responses and protective effects were significantly increased at higher vaccine doses using the i.m. injection route.     

禽类DNA疫苗研究进展

新型疫苗的研究对于禽类传染病的防制意义重大。传统疫苗是基于抗原刺激机体产生特异性抗体的原理,它们大多数激发机体的体液免疫,很难启动细胞免疫。脱氧核糖核酸(DNA)疫苗作为第3代疫苗,具备传统疫苗和其它基因工程苗不可比拟的优点,能够诱导全方位的免疫反应且使用更安全更方便,DNA疫苗是将外源基因与真核质粒重组后直接导入细胞内,使外源基因在宿主细胞内表达合成保护性抗原蛋白。这是模拟病毒自然感染提呈过程,既能产生细胞免疫,又能产生体液免疫。文章对DNA疫苗在禽类应用的可行性和应用研究新进展作了综述。     

禽流感DNA疫苗研究进展

禽流感（avian influenza,AI）是由禽流感病毒（AIV）引起的一种禽类烈性综合征,威胁动物和人类公共健康,严重影响中国养禽业发展,接种疫苗一直是控制禽流感病毒传播最有效的手段。基于基因工程技术的不断发展,各种新型疫苗相继研发并投入使用。其中,禽流感DNA疫苗具有安全性高、制备方法简单、易于储藏和运输等优点,受到了广泛关注。常见的禽流感疫苗有HA DNA疫苗、NA DNA疫苗、M DNA疫苗、NP DNA疫苗等。禽流感DNA疫苗是将含有目的基因序列的重组质粒导入动物细胞,诱导动物机体产生体液和细胞免疫应答。为了提高禽流感DNA疫苗的免疫效果,国内外学者通过添加合适的佐剂、将目的基因导入理想质粒载体、对抗原序列优化,增强DNA疫苗的转染效率和基因表达水平,取得了一定的研究成果。自DNA疫苗开始研发至今,H1、H3、H5、H7、H9等众多亚型禽流感DNA疫苗逐步研发。2018年,由中国农业科学院哈尔滨兽医研究所研制的禽流感H5亚型DNA疫苗获得国家一类新兽药证书,是中国首个获得批准的禽流感DNA疫苗,极大地推动了DNA疫苗的发展。文章主要论述了禽流感DNA疫苗的载体构建、免疫机制、佐剂和载体选择以及疫苗研发等方面的研究进展和创新,并对其应用前景进行简要分析,旨在为科研工作者研制新型禽流感疫苗提供新的思路和参考。     

Review of DNA Vaccine for Avian Influenza

Avian influenza (AI) is a kind of avian virulent syndrome caused by avian influenza virus (AIV),which threatens animal and human public health and seriously affects the development of poultry industry in China.Vaccination has always been the most effective means to control the spread of avian influenza virus.Based on the continuous development of genetic engineering technology,a variety of new vaccines have been developed and put into use.Among them,avian influenza DNA vaccine has many advantages,such as high safety,simple preparation,easy storage and transportation.Common HA DNA vaccine,NA DNA vaccine,M DNA vaccine,NP DNA vaccine.Avian influenza DNA vaccine introduces a recombinant plasmid containing the target gene sequence into animal cells to induce a humoral and cellular immune response.In order to improve the immune effect of avian influenza DNA vaccine,researchers at home and abroad have made some achievements in enhancing the transfection efficiency and gene expression level of DNA vaccine by adding appropriate adjuvants,introducing target genes into ideal plasmid vectors and optimizing antigen sequence.Since the development of DNA vaccines,many subtypes of avian influenza DNA vaccines,including H1,H3,H5,H7 and H9 subtypes,have been gradually developed.In 2018,the H5 subtype DNA vaccine developed by Harbin Veterinary Research Institute of The Chinese Academy of Agricultural Sciences obtained the National Class Ⅰ Veterinary Medicine certificate,which is the first DNA vaccine of avian influenza to be approved in China,greatly promoting the development of DNA vaccines.This review mainly discusses the development and innovation of avian influenza DNA vaccine in terms of vector construction,immune mechanism,adjuvant and vector selection,and vaccine research and development,and briefly analyzes its application prospect,in order to provide new ideas and references for researchers to develop new avian influenza vaccine.