Claerebout E, Vercruysse J
Department of Parasitology, Faculty of Veterinary Medicine, University of Gent, Merelbeke, Belgium.
Parasitology. 2000;120 Suppl:S25-42. doi: 10.1017/s0031182099005776.
The present review discusses the immune responses to gastrointestinal nematodes in cattle and the different immunological and parasitological parameters used to assess acquired immunity. Measuring acquired immunity to gastrointestinal nematodes in cattle (e.g. for the evaluation of candidate parasite vaccines) is hampered by the limited understanding of bovine immune responses against gastrointestinal parasites. In this paper the available data on protective immunity against gastrointestinal nematodes, and especially Ostertagia ostertagi, in cattle are compared with the current knowledge of protective immune responses against gastrointestinal nematodes in rodent models and small ruminants. In contrast to the immune response in mice, which is controlled by T helper 2 (Th2) lymphocytes and results in mast cell- or goblet cell-mediated expulsion of adult worms, bovine immune responses to O. ostertagi do not show a clear Th2 cytokine profile, nor do they result in rapid expulsion of the parasite. The first manifestation of immunity to O. ostertagi in calves is a reduction of worm fecundity, possibly regulated by the local IgA response. Worm numbers are only reduced after a prolonged period of host-parasite contact, and there are indications that O. ostertagi actively suppresses the host's immune response. Until the mechanisms of protective immunity against O. ostertagi are revealed, the use of immunological parameters to estimate acquired immunity in cattle is based on their correlation with parasitological parameters and on extrapolation from rodent and small ruminant models. Assessing the resistance of calves against a challenge infection by means of parasitological parameters is probably still the most accurate way to measure acquired immunity against gastrointestinal nematodes.
本综述讨论了牛对胃肠道线虫的免疫反应以及用于评估获得性免疫的不同免疫和寄生虫学参数。由于对牛针对胃肠道寄生虫的免疫反应了解有限，测量牛对胃肠道线虫的获得性免疫（例如用于评估候选寄生虫疫苗）受到阻碍。在本文中，将牛对胃肠道线虫，特别是奥斯特他线虫的保护性免疫的现有数据与啮齿动物模型和小反刍动物中对胃肠道线虫的保护性免疫反应的现有知识进行了比较。与由辅助性T细胞2（Th2）淋巴细胞控制、导致肥大细胞或杯状细胞介导成虫排出的小鼠免疫反应不同，牛对奥斯特他线虫的免疫反应没有明显的Th2细胞因子谱，也不会导致寄生虫的快速排出。犊牛对奥斯特他线虫免疫的最初表现是虫体繁殖力降低，这可能受局部IgA反应调节。只有在宿主与寄生虫长期接触后虫体数量才会减少，并且有迹象表明奥斯特他线虫会主动抑制宿主的免疫反应。在揭示针对奥斯特他线虫的保护性免疫机制之前，利用免疫参数评估牛的获得性免疫是基于它们与寄生虫学参数的相关性以及从啮齿动物和小反刍动物模型推断得出的。通过寄生虫学参数评估犊牛对攻击感染的抵抗力可能仍然是测量对胃肠道线虫获得性免疫的最准确方法。
