Sharma J M
College of Veterinary Medicine, University of Minnesota, St. Paul 55108, USA.
Adv Vet Med. 1999;41:481-94. doi: 10.1016/s0065-3519(99)80036-6.
The poultry industry constitutes a significant sector of world agriculture. In the United States, more than 8 billion birds are produced yearly with a value exceeding $20 billion. Broiler chickens are the largest segment of the industry. Birds raised under commercial conditions are vulnerable to environmental exposure to a number of pathogens. Therefore, disease prevention by vaccination is an integral part of flock health management protocols. Active immunization using live vaccines is the current industry standard. Routinely used vaccines in chickens include MDV, NDV, IBV, and IBDV, and in turkeys NDV and HEV. Newer vaccines, including molecular recombinants in which genes of immunogenic proteins from infectious agents are inserted into a live viral vector, are also being examined for commercial use. Efforts are under way to enhance vaccine efficacy by the use of adjuvants, particularly cytokines. The vaccine delivery systems include in ovo injection, aerosol, spray, drinking water, eye drop, and wing web injection. The in ovo vaccination procedure is relatively new and at the present time it is used primarily to vaccinate broiler chickens against MDV. Birds respond to vaccines by developing humoral and cellular immune responses. Bursa of Fabricius and the thymus serve as the primary lymphoid organs of the immune system. B cells use surface immunoglobulins as antigen receptors and differentiate into plasma cells to secrete antibodies. Three classes of antibodies are produced: IgM, IgG (also called IgY), and IgA. Successful vaccinal response in a flock is often monitored by demonstrating a rise in antibody titer within a few days of vaccination. ELISA is used most commonly for serologic monitoring. T cells are the principal effector cells of specific cellular immunity. T cells differentiate into alpha beta and gamma delta cells. In adult birds, gamma delta cells may constitute up to 50% of the circulating T cells. Functionally, CD4+ cells serve as helper cells and CD8+ cells as cytotoxic/suppressor cells.
家禽产业是世界农业的一个重要部门。在美国，每年养殖超过80亿只家禽，产值超过200亿美元。肉鸡是该产业中最大的部分。在商业条件下饲养的家禽容易受到多种病原体的环境暴露。因此，通过疫苗接种预防疾病是鸡群健康管理方案的一个组成部分。使用活疫苗进行主动免疫是当前的行业标准。鸡常用的疫苗包括马立克氏病病毒（MDV）、新城疫病毒（NDV）、传染性支气管炎病毒（IBV）和传染性法氏囊病病毒（IBDV），火鸡常用的疫苗包括新城疫病毒和火鸡出血性肠炎病毒（HEV）。新型疫苗，包括将感染性病原体免疫原性蛋白的基因插入活病毒载体的分子重组疫苗，也正在进行商业用途的研究。正在努力通过使用佐剂，特别是细胞因子来提高疫苗效力。疫苗接种途径包括胚内注射、气溶胶、喷雾、饮水、滴眼和翼膜注射。胚内接种程序相对较新，目前主要用于给肉鸡接种马立克氏病病毒疫苗。家禽通过产生体液免疫和细胞免疫反应来对疫苗作出反应。法氏囊和胸腺是免疫系统的主要淋巴器官。B细胞利用表面免疫球蛋白作为抗原受体，并分化为浆细胞以分泌抗体。产生三类抗体：IgM、IgG（也称为IgY）和IgA。通常通过在接种疫苗后几天内证明抗体滴度升高来监测鸡群中成功的疫苗接种反应。酶联免疫吸附测定（ELISA）最常用于血清学监测。T细胞是特异性细胞免疫的主要效应细胞。T细胞分化为αβ和γδ细胞。在成年家禽中，γδ细胞可能占循环T细胞的50%。在功能上，CD4+细胞作为辅助细胞，CD8+细胞作为细胞毒性/抑制细胞。
