In Norway, the tick-transmitted bacterium Anaplasma phagocytophilum is estimated to cause tick-borne fever (TBF) in 300 000 lambs on pastures each year, resulting in economic and animal welfare consequences. Today, prophylactic measures mainly involve the use of acaricides, but a vaccine has been requested by farmers and veterinarians for decades. Several attempts have been made to produce a vaccine against A. phagocytophilum including antigenic surface proteins, inactivated whole cell vaccines and challenge followed by treatment. In the current study, a virulent wild type strain of A. phagocytophilum named Ap.Norvar1 (16S rRNA sequence partial identical to sequence in GenBank acc.no M73220) was subject to genetic transformation with a Himar1-transposon, which resulted in three bacterial mutants, capable of propagation in a tick cell line (ISE6). In order to test the immunogenicity and pathogenicity of the live, mutated bacteria, these were clinically tested in an inoculation- and challenge study in sheep. One group was inoculated with the Ap.Norvar1 as an infection control. After inoculation, the sheep inoculated with mutated bacteria and the Ap.Norvar1 developed typical clinical signs of infection and humoral immune response. After challenge with Ap.Norvar1, 28 days later all groups inoculated with mutated bacteria showed clinical signs of tick-borne fever and bacteremia while the group initially inoculated with the Ap.Norvar1, showed protection against clinical disease. The current study shows a weak, but partial protection against infection in animals inoculated with mutated bacteria, while animals that received Ap.Norvar1 both for inoculation and challenge, responded with homologues protection.

在挪威，估计每年通过tick传播的噬菌嗜性无花果厌食杆菌会在牧场上引起30万只羔羊的tick传播热（TBF），从而造成经济和动物福利后果。今天，预防措施主要涉及杀螨剂的使用，但是几十年来，农民和兽医一直要求使用疫苗。已经进行了数种尝试来生产抗吞噬嗜血曲霉的疫苗，包括抗原性表面蛋白，灭活的全细胞疫苗和攻击后进行治疗。在目前的研究中，一个致命的野生型菌株A.吞噬细胞命名为Ap.Norvar1（与GenBank编号M73220中的序列部分相同的16S rRNA序列）用Himar1-转座子进行了遗传转化，产生了三个细菌突变体，能够在壁虱细胞系（ISE6）中繁殖。为了测试活的突变细菌的免疫原性和致病性，已在绵羊的接种和攻击研究中对它们​​进行了临床测试。一组接种了Ap.Norvar1作为感染对照。接种后，绵羊接种了突变的细菌，Ap.Norvar1出现了典型的感染和体液免疫反应的临床体征。用Ap.Norvar1攻击后，接种突变细菌的所有组在28天后均表现出tick传热和菌血症的临床体征，而最初接种Ap.Norvar1的组，对临床疾病具有保护作用。当前的研究表明，在接种了突变细菌的动物中，对感染的保护作用较弱，但部分保护作用很小，而同时接受Ap.Norvar1接种和攻击的动物则对同系物有反应。