Development of a vaccine to control poultry red mite

家禽红螨（PRM）对鸡舍的侵扰使欧盟家禽业每年损失约1.3亿欧元（每只母鸡约0.43欧元）。这些螨虫白天生活在笼子里难以接近的地方，晚上出现在笼子里以母鸡为食，咬破母鸡的皮肤以血液为食。因此，这种寄生虫在生产设施中的感染对动物福利有重要影响，包括贫血、刺激和不安加剧、啄羽毛和同类相食的发生率增加。这些行为对生产力有相当大的负面影响。家禽红螨还被认为是一些重要禽类疾病的携带者，最近根据其致敏性建议将其列为家禽工人的一种职业危害。直到最近，在鸡舍没有人口的时期（即在产卵周期开始时引入新鸟之前），通过在鸡舍中喷洒农药来控制PRM的侵扰。控制螨的数量现在是一个主要问题，大多数杀虫剂只能有限地或短暂地减少螨的数量。此外，由于对安全和环境污染的担忧，许多目前有效的农药已经停止使用，对剩余化合物的抗药性的出现加剧了螨虫控制的这些问题。疫苗接种是化学治疗的一种安全有效的替代方法。现在人们认识到，针对吸血寄生虫的疫苗可以实现有效和可持续的控制，我们以前的工作已经明确确定，针对PRM的疫苗接种是可行的和可交付的。一种商业上可行的抗PRM疫苗应含有一种高效合成的螨虫蛋白（“抗原”），或者不太理想的情况是含有少量这种蛋白质的混合物。Moredun先前的研究表明，用PRMs提取物接种蛋鸡可以诱导以接种鸡的血液为食的螨虫死亡，并控制螨虫的数量。这些研究表明：1)血液中针对螨虫抗原的抗体可导致螨虫显著死亡，且这种效果（死亡）发生在24小时内；2)重组蛋白也可以达到类似的效果，重组蛋白更容易持续生产，因此适合大规模生产。因此，拟议工作的总体目标是：1)鉴定PRM提取物的保护性免疫原性亚组分；2)结合免疫印迹和蛋白质组学分析，鉴定这些亚组分中的免疫原性抗原；3)制备这些免疫原性蛋白的亚群作为重组蛋白，并在母鸡体内培养针对这些重组蛋白的抗体；4)在我们的实验室饲养系统中测试这些抗体对螨虫死亡率和/或发育的影响；5)从筛选中选择最有效的重组抗原，在现场疫苗试验中进行组合试验。如果成功，该项目将提供首个针对体外寄生虫开发的重组疫苗，该疫苗将在全球范围内分布，从而开拓市场。我们将使用创新技术，结合Moredun独特的PRM基因组数据和专业的蛋白质分析设备来识别保护性抗原，在重组系统中生产它们，并在我们的行业合作伙伴可以提供的最有效的疫苗学的背景下将它们提供给鸟类。

Infestation of hen houses with the poultry red mite (PRM) costs the poultry industry an estimated 130 million euros per annum in the EU (approximately 0.43 euros per hen). The mites live, off-host, in inaccessible areas of the cages during daylight and emerge during darkness to feed on the hens, biting through the skin to feed on blood. Infestation of production facilities with this parasite therefore has important animal welfare implications including anaemia, increased irritation and restlessness, feather-pecking and an increased incidence of cannibalism. These behaviours have a considerable negative impact on productivity. Poultry red mites have also been implicated as carriers for a number of important avian diseases and have recently been recommended to be listed as an occupational hazard for poultry workers on the basis of their allergenicity. Until recently, PRM infestation has been controlled with the use of pesticide sprays in hen houses during the period that the houses are not populated (i.e. before the introduction of new birds at the start of a laying cycle). Controlling mite populations is now a major problem, with most pesticides affording only limited or short-lived reduction in the population of mites. Also, because of concerns over safety and environmental contamination, many of the currently effective pesticides have been withdrawn from use and the emergence of resistance to the remaining compounds has exacerbated these problems with mite control. Vaccination offers a safe, effective alternative to chemical treatments. It is now recognised that vaccines to blood-feeding parasites can result in effective and sustainable control and our previous work has clearly established that vaccination against PRM is feasible and deliverable. A commercially viable vaccine against PRM should contain one highly effective synthetic version of a mite protein ("antigen") or, less ideally, a cocktail incorporating a small number of such proteins. Previous studies at Moredun have shown that vaccination of laying hens with extracts of PRMs can induce mortality in mites feeding on the blood of vaccinated hens and control mite numbers. These studies have shown that: i) Antibodies to mite antigens in the blood can cause significant mite mortality, and this effect (mortality) occurs within 24 hours, and ii) a similar effect can be achieved with recombinant proteins which are easier to produce consistently and hence lend themselves to large scale production. The overall objectives of the proposed work are therefore: 1) To identify protective immunogenic sub-fractions of the PRM extract; 2) To identify the immunogenic antigen(s) in these sub-fractions by combined immunoblotting and proteomic analyses; 3) To produce a sub-set of these immunogenic proteins as recombinant proteins and raise antibodies against these recombinants in hens; 4) To test these antibodies for mite mortality and/or developmental effects in our lab-based feeding system; 5) To select the most potent recombinant antigens from this screen to test in combination, in a field vaccine trial.If successful, this project will deliver the first recombinant vaccine to be developed against an ectoparasite with a worldwide distribution and, therefore, market. We will use innovative technologies, coupling Moredun's unique PRM genomic data and specialist protein analysis facilities to identify the protective antigens, produce them in recombinant systems and deliver them to the birds in the context of the most effective vaccinology that our industry partner can supply.