Grønvold J, Nansen P, Gasbarre L C, Christensen C M, Larsen M, Monrad J, Midtgaard N
Department of Veterinary Microbiology, Royal Veterinary and Agricultural University, Frederiksberg, Denmark.
Acta Vet Scand. 1992;33(4):305-16. doi: 10.1186/BF03547296.
This experiment comprised 3 groups of calves, (+P2), (-P2) and (-P1), which all started their first grazing season as parasite-free calves. The (+P2)- and (-P2)-group grazed 2 seasons. In the first season the (-P2)-group of calves was grazing a pasture with no detectable trichostrongyles and treated with anthelmintics every second week. The untreated (+P2)-group grazed an Ostertagia ostertagi contaminated pasture. During the second grazing season these 2 original groups grazed together with a new group of first-year grazing calves (-P1) on paddocks infected with O. ostertagi. Parasitological analyses showed that (+P2)-group had negligible egg excretions in the second year in comparison with (-P2) and (-P1). This indicated, that the egg output may be regulated through acquired immunity. The difference in egg excretions was not reflected in the serum pepsinogen levels, which were only slightly elevated for all groups in the second year. Post mortem examination at the end of the experiment showed that only the (-P1)-group harboured relatively high numbers of worms in the abomasa at that time. Antibodies of 3 immunoglobulin classes were investigated: IgA, IgG1 and IgG2. The IgA and IgG1 responses correlated with the presence of developing and adult worms in the abomasa and they remained elevated in the (+P2)-group throughout the experiment, perhaps indicating an involvement of these antibodies in a protective immune response. In the (-P2)-group the IgA and IgG1 showed fast and sharp rises during the second season that most likely were age-related and as such a result of maturation of the immune system. The role of IgG2 is unclear as the IgG2 response was weak in all groups of calves and difficult to relate to the parasitological data.
本实验包括3组犊牛，即（+P2）组、（-P2）组和（-P1）组，所有犊牛在首个放牧季节开始时均未感染寄生虫。（+P2）组和（-P2）组犊牛放牧两个季节。在第一个季节，（-P2）组犊牛在一个未检测到毛圆线虫的牧场放牧，每隔一周用驱虫药进行处理。未处理的（+P2）组犊牛在一个感染了奥氏奥斯特线虫的牧场放牧。在第二个放牧季节，这两个原始组与一群新的第一年放牧犊牛（-P1）一起在感染了奥氏奥斯特线虫的围场放牧。寄生虫学分析表明，与（-P2）组和（-P1）组相比，（+P2）组在第二年的虫卵排泄量可忽略不计。这表明，虫卵产量可能通过获得性免疫进行调节。虫卵排泄量的差异在血清胃蛋白酶原水平上并未体现出来，所有组在第二年血清胃蛋白酶原水平仅略有升高。实验结束时的尸检表明，当时只有（-P1）组在皱胃中寄生有相对较多的蠕虫。研究了三种免疫球蛋白类别的抗体：IgA、IgG1和IgG2。IgA和IgG1反应与皱胃中发育中和成虫的存在相关，并且在整个实验过程中（+P2）组一直保持升高，这可能表明这些抗体参与了保护性免疫反应。在（-P2）组中，IgA和IgG1在第二个季节迅速大幅上升，这很可能与年龄有关，是免疫系统成熟的结果。IgG2的作用尚不清楚，因为所有犊牛组的IgG2反应都很弱，且难以与寄生虫学数据相关联。
