A novel platform for producing cell-free third generation Marek's disease virus vaccine

马立克氏病病毒（MDV）感染鸡，并导致致命的淋巴组织增生性疾病，只有通过大规模接种疫苗才能控制。针对MDV的最有效的疫苗是减毒MDV（病毒的弱化形式），其感染鸡但不引起疾病。在鸡中，MDV和“金标准”MDV疫苗都保留在感染的细胞内（细胞相关），而无细胞形式的病毒（一种可以在细胞外保持感染性的病毒）仅由位于羽囊中的特定细胞类型产生。无细胞病毒从受感染或接种疫苗的鸟类的羽毛脱落，这些无细胞病毒在家禽养殖场吸入受感染的灰尘后感染其他鸟类。目前，每年有220亿剂MDV疫苗接种鸡。家禽疫苗制造商目前在从受精卵和含胚卵分离的细胞中生产MDV疫苗。因此，疫苗接种的成本非常高，因为疫苗必须在非常低的温度（液氮）下储存和运输，这需要昂贵的设备、训练有素的人员和特殊的处理程序。当前疫苗的另一个缺点是，储存和处理中的任何错误都可能降低疫苗的有效性。我们的目标是生产一种无细胞的疫苗，因此它不需要非常低的储存或运输温度。在这个项目中，我们将开发一个生产无细胞MDV疫苗的平台，通过从羽毛毛囊中产生细胞，这些细胞具有以无细胞形式生产病毒的能力。我们将在实验室中建立提高细胞系生产无细胞MDV疫苗的能力的方法，并最终在鸡中检测MDV无细胞疫苗的免疫原性和效力。

Marek's disease virus (MDV) infects chickens and causes a deadly lymphoproliferative disease which is only controlled by mass vaccination. The most effective vaccine against MDV is an attenuated MDV (weaken form of virus) which infects chickens but does not cause the disease. In chickens, both MDV and the "gold standard" MDV vaccine remain within the infected cells (cell-associated) and cell-free form of virus (a virus which can stay infective outside of cell) is only produced by a specific cell type located in the feather follicles. Cell-free virus is shed from the feathers of infected or vaccinated birds and these cell-free viruses infect other birds after inhalation of the infected dust in the poultry farms. Currently, 22 billion doses of MDV vaccine are administered to chickens annually. Poultry vaccine manufacturers currently produce MDV vaccines in cells isolated from fertilized and embryonated eggs. Therefore, the cost of vaccination is very high as the vaccine has to be stored and transported in very low temperatures (liquid nitrogen) which requires expensive equipment, trained individuals, and special handling procedures. Another disadvantage of the current vaccine is that any error in storage and handling can reduce the effectiveness of the vaccine. We aim to produce a vaccine that is cell-free and thus it does not require very low temperatures for storage or transportation. In this project, we will develop a platform for the production of cell-free MDV vaccine by generating cells from feather follicles with the capability to produce the virus in a cell-free form. We will establish methods to increase the capacity of the cell lines to produce the cell-free MDV vaccine in the laboratory, and finally we will examine the immunogenicity and efficacy of the MDV cell-free vaccine in chickens.