Development of the Japanese Encephalitis Virus DNA Vaccine for Swine

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Project title

Code/計畫編號

NSC94-2317-B019-001

Translated Name/計畫中文名

日本腦炎DNA疫苗在豬隻之效能研發

Project Coordinator/計畫主持人

Chang-Jer Wu

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Food Science

Website

https://www.grb.gov.tw/search/planDetail?id=1122080

Year

2005

Start date/計畫起

01-08-2005

Expected Completion/計畫迄

01-07-2006

Bugetid/研究經費

1530千元

ResearchField/研究領域

生物技術(農)
畜牧獸醫

"日本腦炎病毒是一種經由蚊子傳播的病毒，每年在東亞及南亞等地區造成嚴重的疾病及畜產損害，包括人、馬及懷孕母猪等。施打疫苗是目前控制動物感染性疾病發生的最好方法。所以，發展有效的畜產用及人用疫苗技術是世界潮流的新趨勢。目前接種日本腦炎疫苗對人或畜產確實提供很好的保護效果，但現行傳統的日本腦炎死毒疫苗，不但成本高，有時會引起一些副作用，因此新疫苗的開發有其迫切性。近年來，DNA 疫苗對疫苗的研發提供了一個新的發展領域，同時也改善了傳統疫苗的缺點，並有取代現有的傳統疫苗的趨勢。過去幾年，在農業生物技術國型科技計畫支持下，我們構築了同時攜帶日本腦炎病毒膜及外套蛋白的DNA 質體(pME)，在小鼠實驗中，我們發現同時攜帶日本腦炎病毒膜及外套蛋白的DNA 質體不需要蛇毒蛋白的前處理，就能產生比質體pE 所引起更強烈且長時間的抗體反應。而且在電子顯微鏡的觀察下，發現DNA 質體pME 在BHK 細胞裡可以產生無致病力的偽日本腦炎病毒，是一個很有效率的日本腦炎DNA 疫苗。到目前的DNA 疫苗研究大部份都是在小型動物—小鼠進行實驗，而且都可以引起很好的免疫保護力，一但DNA 疫苗運用到大型動物實驗時，都只能引起微弱的免疫反應。明顯地，有需要再提高DNA 疫苗在猪的免疫效能，並增強DNA 疫苗在大型動物的保護性免疫力。那我們為何選擇猪作為日本腦炎DNA 疫苗的大型動物實驗，因為牠具有下列優點：第一、猪是屬於一種很好飼養及操作實驗的家畜。第二、猪是日本腦炎病毒的中間宿主，也會造成公猪之附睪會發生硬化而造成不孕症及懷孕母猪發生流產，影響畜產界甚大。所以，可藉由發展猪日本腦炎DNA 疫苗，研究如何增強並改良DNA 疫苗在大型動物的保護性免疫力，並建立畜產用DNA 疫苗產業技術基礎。在本計劃中，我們將採用幾種方式來改進日本腦炎DNA 疫苗在猪動物模式的免疫力。首先，我們會利用高表現率的載體來攜帶日本腦炎病毒「膜-外套」融合蛋白基因，測試在猪動物模式上的免疫效果，並與傳統疫苗進行比較。第二，在猪動物模式中，找出日本腦炎DNA 疫苗以肌肉注射及基因槍傳輸途徑的最佳免疫條件。第三，比較猪動物模式中，各種日本腦炎DNA 疫苗的傳輸途徑所引發的免疫反應及效果差異，包括﹕肌肉注射、基因槍、體外電擊等。經由上述的研究，我們希望能在大型動物猪動物模式上發展方便及有效的日本腦炎DNA 疫苗，作為發展有效的畜產用DNA 疫苗平台的基礎。" "Japanese encephalitis virus (JEV) is a mosquito-transmitted virus that causes disease in human, horses, and pregnant swine each year in southern and eastern Asia. The global trend in vaccine technology-mass vaccination in livestock has been an important thrust contributing to the control of animal infectious diseases. Vaccination has been observed to protect against JEV infection in humans and domestic animals. But, the conventional mouse brain-derived vaccine poses several adverse effects that are increasingly less tolerated. Thus, renewed interests in search of innovated technology for use in vaccine development have been a visible global phenomenon. DNA vaccine represents an innovated novel approach to vaccine research and might potentially circumvent some of the shortcomings of the conventional vaccine. In the past few years, with the support of National Science and Technology Program for Agricultural Biotechnology, we generated plasmid (pME) encoding JEV structural membrane-envelope protein (ME). In the mouse model, we demonstrated that the plasmid pME was able to elicit a higher level of protection against a lethal JEV challenge than plasmid pE without cardiotoxin pretreatment. We also found that the plasmid pME, which expressed pseudo-JEV particles in vitro by electron microscopy, was an effective DNA vaccine without cardiotoxin. To date, most of the studies on DNA vaccines have been performed on small animals, largely in mice. However, the DNA vaccine when applied in the large animals only induced a weak immune response. Apparently, more efficient immunization strategy is required to obtain high titers of protective immunity in the large animals. There are several advantages to use the domestic swine as the large animal model to investigate potential DNA vaccination protocols. First, the domestic swine represent an outbreed population and are relatively easy to house and handle. Second, swine are natural hosts to JEV, and hence the DNA vaccines can be tested in a relevant natural virus-host system instead of in experimental model systems. In this proposed grant, we will adopt several strategies to improve the immunogenicity of JEV DNA vaccine in the swine model. The improvement of a most effective antigen-specific immunity by DNA vaccines involves optimization of the vaccine design and effective antigen processing. First, we will test the efficacy of JEV DNA vaccine, a highly expression vector to carry the JEV membrane-envelope, in swine model and compare with the traditional vaccine. Second, the delivery conditions of JEV DNA vaccine by the intramuscular injection and gene gun will be optimized to achieve better immunization. Third, to comparatively analyze the efficacy and responses of the different delivery routes of JEV DNA vaccine included intramuscular injection, gene gun and in vivo electroporation. Through all these efforts, we hope to develop an effective JEV DNA vaccine in the swine model and prepare the preclinical data for a future livestock vaccine."

Keyword(s)

日本腦炎病毒
DNA 疫苗
肌肉注射
基因槍
猪的動物模式
Japanese encephalitis virus
DNA vaccine
intramuscular injection
gene gun
swine model

DSpace CRIS

Development of the Japanese Encephalitis Virus DNA Vaccine for Swine

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