du Plessis J L, Bezuidenhout J D
J S Afr Vet Assoc. 1979 Dec;50(4):334-8.
Sixty cattle, artificially immunized against C. ruminantium, were challenged 3, 6, 12 and 24 months later. Levels of conglutinin were determined in pre-immunization serum samples. There appeared to be a relationship between the pre-infection levels of conglutinin and the susceptibility of the animals to heartwater: At the time of immunization 31 out of 60 cattle (51,6%) with levels in the low-titre range (1:100-1:160) showed a typical febrile response, whereas 29 (48,4%) with conglutinin levels in the high-titre range (1:320 and higher) were either fully or partially resistant. Except for 2 animals that developed mild febrile reactions when they were challenged 2 years after artificial immunization, all the cattle were fully resistant to challenge with C. ruminantium infected sheep blood. It can be concluded that in this experiment cattle retained their immunity to heartwater for at least 2 years in the absence of reinfection.
60头人工免疫了反刍兽类无浆体的牛，在3、6、12和24个月后接受了攻毒。在免疫前的血清样本中测定了凝集素水平。凝集素的感染前水平与动物对心水病的易感性之间似乎存在关联：在免疫时，60头牛中有31头（51.6%）凝集素水平处于低滴度范围（1:100 - 1:160），表现出典型的发热反应，而29头（48.4%）凝集素水平处于高滴度范围（1:320及以上）的牛则完全或部分具有抗性。除了2头在人工免疫2年后接受攻毒时出现轻度发热反应的牛外，所有牛对用感染反刍兽类无浆体的绵羊血液进行的攻毒均完全具有抗性。可以得出结论，在本实验中，牛在没有再次感染的情况下对心水病保持了至少2年的免疫力。
