鸡球虫重组疫苗的研究进展

球虫病是由艾美耳球虫引起的一种对家禽危害极为严重的全球性寄生虫病,目前仍以药物防治为主。由于球虫抗药株的不断出现、研制新药的费用昂贵和药物残留的日趋严重,使得球虫疫苗研究成为近年的热点。采用ＤＮＡ重组技术获得的重组疫苗逐渐受到人们的重视,发展很快。综述近年来家禽球虫重组疫苗的研究情况,探讨重组疫苗的利用前景、存在问题和解决途径。     

莫能菌素通过成果鉴定

莫能菌素(Monensin)是应用最广泛的抗球虫多醚抗生素之一。自1974年在美国开始应用以来,分别在鸡、羊、兔、肉牛等家禽家畜上用来控制各种球虫病,提高饲料转化率和增加体重,取得了巨大经济效益。该药对鸡的球虫病具有良好的防治效果,在150ppm时可以抑制鸡球虫的孢子卵囊的萌发,从而显著地降低死亡     

柔嫩艾美耳球虫广东株子孢子折光体抗原Etp28基因的克隆和序列分析

鸡球虫病是由顶器官亚门（Ａｐｉｃｏｍｐｌｅｘａ）艾美耳属（Ｅｉｍｅｒｉａ）的一种单细胞寄生原虫引起的严重危害家禽生长发育的疾病。其中,柔嫩艾美耳球虫（Ｅｉｍｅｒｉａｔｅｎｅｌａ）通过在鸡的盲肠上皮细胞内进行裂体生殖,形成大量的裂殖体并引起广泛出血而造...     

鸡球虫入侵机理、免疫学性质及基因工程在疫苗研制上的应用

鸡球虫病是严重危害养禽业的一种寄生虫病。长期以来主要以化学药物进行防治。但由于球虫抗药性和药物残留等问题日益严重,使得新药开发和应用受到限制。在免疫学中强毒活苗应用广泛但生产费用昂贵,从而促使我们转向对重组亚单位疫苗的研究。不同种类的球虫有较为严格的寄生部位。且不同发育阶段的球虫其免疫原性和抗原构成也有很大差异。在真核寄生生物中,由于受到宿主免疫系统的限制,选用鸡球虫免疫保护性抗原做重组疫苗目前还没有很大突破,因此我们需要采用新方法发现新抗原,有效防治鸡球虫病。     

重庆市中药研究院实验兔球虫感染种类调查

2009年6月对重庆市中药研究院实验兔场的实验兔球虫感染种类进行了调查.采用兔粪分离沉淀孵化法获得充分孢子化的卵囊,通过对卵囊形态鉴定,发现该兔场的家兔感染球虫达13种之多,以斯氏艾美尔球虫(占23％)、盲肠艾美尔球虫(占15.33％)、大型艾美尔球虫(占12.67％)和长形艾美尔球虫(占12％)4种为主,长艾美尔球虫和那格浦耳艾美尔球虫在重庆地区首次被检出.提示很有必要深入调查重庆地区的兔球虫种类和感染强度,积极探索适合重庆特点的兔球虫病防制措施和方法.     

云南省黄牛球虫的种类包括艾美球虫一新种的描述

国内牛球虫病已屡见报告,但关于牛球虫种类,牛群感染情况等尚未见有系统的调查。1981年2月至1982年3月,我们在云南省三个地、州、市的六县一市共调查黄牛372头,检查出12种球虫卵囊,11种为艾美球虫(Eimeria),其中包括一新种;1种为等孢球虫(Isospora)。统计了牛群和不同年龄牛的球虫感染率以及单种感染和混合感染的情况。并绘制了球虫卵囊图以兹参考。     

柔嫩艾美耳球虫(Eimeria tenella)早熟株与亲本株致病性和繁殖力的研究

通过对经15代选育的柔嫩艾美耳球虫(E. tenella)山西株的早熟株与其亲本株的繁殖力和致病性进行比较研究,证实早熟株的潜隐期比亲本株缩短21 h,繁殖力下降40%左右;对致病性的研究显示,早熟株感染后对鸡只增重、AC I的影响较小,对11日龄雏鸡的半数感染量和半数致死量较亲本株增大,肠道病变记分较亲本株下降。由此认为,该早熟株符合球虫早熟株的特性,可用于鸡球虫病早熟苗的制作。     

特异性高免卵黄抗体与鸡柔嫩艾美尔球虫致病关系的研究

为了探讨体液免疫在鸡球虫病中的作用,通过制备柔嫩艾美尔球虫(E.tenella)特异性高免卵黄抗体,检测卵黄抗体在鸡盲肠中的代谢规律,对E.tenella进行体内外抑制和杀灭实验,观察特异性高免卵黄抗体对E.tenella的作用。结果表明:(1)口服的卵黄抗体在鸡消化道较稳定;(2)口服卵黄液可使感染E.tenella鸡的死亡率降低33.34%,增重率和抗球虫指数分别提高39.19%和73.50;(3)特异性高免卵黄抗体对E.tenella的子孢子具有明显的溶解和致弱作用,但对卵囊的孢子化速率和孢子化球虫卵囊的致病性没有明显影响。     

益生菌抗结肠癌作用及分子机制研究进展

益生菌是指一类通过改善肠内菌群平衡,对宿主起到有益作用的活性微生物,具有提高免疫力、抗过敏、缓解炎性肠道疾病、抗感染、抗癌等生物学功能.本文首先阐述益生菌、益生菌发酵液、其菌体成分、代谢成分抗结肠癌作用的研究进展;随后阐述其抗结肠癌的分子机制,主要包括;免疫调节和抗炎症作用,抑制细胞增殖和促进细胞凋亡,产生有益的代谢物和抑制致癌物活化酶与遗传解毒;最后介绍益生菌在临床医学研究中的应用情况,益生菌不仅可以在结肠癌发生过程中起到一定的保护作用,且能够很好的改善结肠术后患者的肠道相关症状.目前,益生菌菌体活性成分的分离及其功能研究也逐渐成为新的研究热点,这些将为更深入准确地了解益生菌的作用机制,更好的、更快的、更全面的利用益生菌及其制剂提供新的思路和途径.     

EGFP标记柔嫩艾美耳球虫重组卡介苗的构建及其在鸡体内的分布

鸡球虫病给禽类养殖业带来重大经济影响。本实验利用DNA重组技术将柔嫩艾美尔球虫保护性抗原基因rhomboid和增强型绿色荧光蛋白EGFP基因串连,将其克隆到BCG中,构建EGFP标记柔嫩艾美耳球虫重组卡介苗pMV361-Rho／EGFP。将rBCG口服免疫6日龄雏鸡,一周后剖杀,取肝、脾、肺、肾、盲肠各组织器官制作冰冻切片,激光共聚焦显微镜观察各组织器官rhomboid表达情况。另分别于免疫后7,14,21,28天提取肝、脾、肺、肾、盲肠各组织器官总RNA,实时定量RT-PCR方法检测rhomboid目的基因转录情况,比较各时期组织器官rhomboid基因表达量。结果显示,免疫一周后,用激光共聚焦显微镜观察到在肝、脾、肺、肾、盲肠各组织器官中均有EGFP表达。实时定量RT-PCR结果显示,免疫14天后rhomboid基因表达量达到高峰,随后开始下降,至28天后消失。本研究为重组卡介苗疫苗作为抗球虫疫苗的研究奠定基础。     

Dietary supplementation of mannan-oligosaccharide enhances neonatal immune responses in chickens during natural exposure to <Emphasis Type="Italic">Eimeria</Emphasis> spp

Background  

Control and eradication of intestinal infections caused by protozoa are important biomedical challenges worldwide. Prophylactic control of coccidiosis has been achieved with the use of anticoccidial drugs; however, the increase in anticoccidial resistance has raised concerns about the need for new alternatives for the control of coccidial infections. In fact, new strategies are needed to induce potent protective immune responses in neonatal individuals.     

Biotechnological advances in the diagnosis of avian coccidiosis and the analysis of genetic variation in Eimeria

Coccidiosis is an intestinal disease of chickens caused by various species of protozoan parasites within the genus Eimeria. This disease has a major economic impact to growers and to the poultry industry world-wide. The diagnosis and genetic characterization of the different species of Eimeria are central to the prevention, surveillance and control of coccidiosis, particularly now given the major problems with wide-spread resistance of Eimeria species against anticoccidial drugs (coccidiostats) and the residue problems associated with these compounds. While traditional methods have had major limitations in the specific diagnosis of coccidiosis, there have been significant advances in the development of molecular-diagnostic tools. The present article provides a background on coccidiosis, reviews the main molecular methods which have been used and describes recent advances in the establishment of polymerase chain reaction (PCR)-coupled electrophoretic approaches for the specific diagnosis of coccidiosis as well as the genetic characterization of species of Eimeria. These biotechnological advances are considered to represent a significant step toward the improved prevention and control of this important disease of poultry.     

Development of a genetically engineered vaccine against poultry coccidiosis

Coccidiosis is caused by infection with Eimeria spp. The disease is responsible for major economic loss to the poultry industry unless infections are controlled by anticoccidial drugs. John Ellis and Fiona Tomley discuss recent research on the characterization and cloning of antigens from Eimeria spp and advances towards the development of genetically engineered vaccines against poultry coccidiosis.     

Biotechnological advances in the diagnosis of avian coccidiosis and the analysis of genetic variation in Eimeria

Coccidiosis is an intestinal disease of chickens caused by various species of protozoan parasites within the genus Eimeria. This disease has a major economic impact to growers and to the poultry industry world-wide. The diagnosis and genetic characterization of the different species of Eimeria are central to the prevention, surveillance and control of coccidiosis, particularly now given the major problems with wide-spread resistance of Eimeria species against anticoccidial drugs (coccidiostats) and the residue problems associated with these compounds. While traditional methods have had major limitations in the specific diagnosis of coccidiosis, there have been significant advances in the development of molecular-diagnostic tools. The present article provides a background on coccidiosis, reviews the main molecular methods which have been used and describes recent advances in the establishment of polymerase chain reaction (PCR)-coupled electrophoretic approaches for the specific diagnosis of coccidiosis as well as the genetic characterization of species of Eimeria. These biotechnological advances are considered to represent a significant step toward the improved prevention and control of this important disease of poultry.     

A compartmentalised model for the estimation of the cost of coccidiosis to the world's chicken production industry

A compartmentalised model is presented for the estimation of the monetary losses suffered by the world's poultry industry resulting from coccidiosis of chickens and costs of its control. The model is designed so that the major elements of loss may be separately quantified for any chicken-producing entity, e.g., a farm, a poultry company, a country, etc. Examples are presented and the sources, reliability and geographical relevance of the data used for each parameter are provided. Loss elements for specific geographical areas should be recalculated at appropriate intervals to take into account local and international fluctuations in costs of chicks feed, labour, financial inflation and world currency exchange rates. Equations are given for relationships among numbers of chickens, liveweights, weights of carcasses, feed consumptions, feed conversion ratio (FCR), prices of feeds, prices of anticoccidial therapeutic and prophylactic drugs, values of chickens, chicken rearing costs; and effects of coccidiosis on mortality, weight gain and FCR. Using these equations, it is theoretically possible for an international team of representatives, each using reliable local data, to calculate simultaneously each relevant loss element for their respective countries. Addition of these elements could give, for the first time, an accurate global estimate of the losses due to chicken coccidiosis. The total cost of coccidiosis in chickens in the United Kingdom in 1995 is estimated to have been at least GB pound silver 38 588 795, of which 98.1% involved broilers (80.6% due to effects on mortality, weight gain and feed conversion, and 17.5% due to the cost of chemoprophylaxis and therapy). The costs of poor performance due to coccidiosis and its chemical control totalled 4.54% of the gross revenue from UK sales of live broilers. This model includes a new method for comparing the profitabilities of different treatments in commercial trials. providing actual costs rather than the arbitrary numerical scores of other methods. Although originally designed for the study of coccidiosis, the model is equally applicable to any disease. It should be of value to agricultural economists, the animal feed and poultry industries, animal health companies, and to research scientists (particularly for preparing grant applications).     

Resistance to anticoccidial drugs in fowl

Resistance has been encountered wherever drugs have been used extensively for the control of parasitic infections. The poultry industry is dependent upon drugs for the control of coccidiosis, a major disease of chickens caused by protozoan parasites of the genus Eimeria. In modern poultry production, drugs are used prophylactically for the prevention of coccidiosis by including them in the diet. This has inevitably led to the development of resistance. We have been fortunate in that new drugs have become available to replace those to which resistance has developed, but this situation is unlikely to continue. The problem of drug resistance, discussed here by David Chapman, has provided impetus for the development of new approaches (such as vaccination) for the control of coccidiosis.     

Sustainable coccidiosis control in poultry production: the role of live vaccines

The development of new methods of administering coccidiosis vaccines has facilitated their use in the hatchery and thereby improved prospects for the economic vaccination of broilers. The acquisition of protective immunity to Eimeria species is boosted by further exposure to infection after vaccination. Factors that affect the reproductive efficiency of non-attenuated and attenuated vaccines are considered and the key role that oocyst production plays in establishing and maintaining uniform immunity in a flock of chickens is discussed. In addition to immunisation, a possible advantage to the application of certain vaccines is that their use could repopulate poultry houses with drug-sensitive organisms. Theoretical rotation programmes in which the use of drugs is alternated with that of vaccines are described. Variability of the cross-protective immune response between strains of the same species should be considered during vaccine development and subsequent use. The significance of less common species of Eimeria, not included in all vaccines, also needs to be assessed. An important consideration is the occurrence of pathogens other than Eimeria (such as the bacterium Clostridium) in flocks given coccidiosis vaccines and the methods by which they might be controlled. More research is required into the relationship between bacterial and viral infections of poultry and coccidiosis vaccination. Vaccines need to be developed that are simple to apply and cost effective for use in areas of the world where small-scale poultry production is commonplace. In the near future it is likely that more live vaccines based upon oocysts derived from attenuated strains of Eimeria will be developed but in the longer term vaccines will be based on the selective presentation to the host of specific molecules that can induce protective immunity. This achievement will require significant investment from the private and public sectors, and, if successful, will facilitate the sustainable control of coccidiosis in poultry production.     

畜禽中药-益生菌复合微生态制剂的研究进展

畜禽中药-益生菌复合微生态制剂是指采用现代发酵技术将益生菌与中药联合发酵,发挥两者的协同作用,以提高畜禽免疫功能、保护畜禽健康的一种新型动物微生态制剂。文中通过调研近几年关于益生菌及中药微生态制剂等方面的文献,综述了畜禽中药-益生菌复合微生态制剂的产生背景及菌种特点,并重点阐述了畜禽中药-益生菌复合微生态制剂的作用机制、在畜禽养殖中的应用及存在问题与建议,以期为畜禽中药-益生菌复合微生态制剂的深入研究提供参考和依据。