Wiedmer Stefanie, Alnassan Alaa Aldin, Volke Beate, Thabet Ahmed, Daugschies Arwid, Lendner Matthias, Kurth Michael
Technische Universität Dresden, Institut für Zoologie, Spezielle Zoologie und Parasitologie, Zellescher Weg 20b, 01217 Dresden, Germany.
Universität Leipzig, Institut für Parasitologie, An den Tierkliniken 35, 04103 Leipzig, Germany.
Vet Parasitol. 2017 Nov 30;247:100-107. doi: 10.1016/j.vetpar.2017.09.019. Epub 2017 Sep 25.
Eimeria species cause avian coccidiosis leading to substantial economic losses in the poultry industry. Hence, anticoccidial drugs and vaccines have been used to combat this devitalizing disease. An effective vaccine based on gametocyte recombinant proteins would be very useful in terms of cost, labor and ethics (no animal experimentation). A mouse derived monoclonal antibody against Eimeria tenella gametocyte antigen 56 (EtGAM56) was used to immunize peritoneally E. tenella infected chicken a reduction of oocyst shedding by up to 78% was observed. The epitope recognized by the monoclonal antibody was mapped, recombinant expressed and used to immunize chicken (rEtGAM56N). After rEtGAM56N intramuscular immunization and parasite challenge, clinical parameters like faecal oocyst output, body weight gain, lesion score, feed conversion rate and serum antibody response were assessed to test the efficacy of vaccination against experimental infection with E. tenella. Chicken immunized with rEtGAM56N and challenged with E. tenella oocysts showed a robust antibody response against the rEtGAM56N peptide but no considerable effects on oocyst output and clinical parameters (weight gain, lesion score, feed conversion rate) compared to the mock control group. This study demonstrates the complexity of an effective vaccination. The immunoprotective epitope might be a conformational epitope that was recognized by the monoclonal mouse antibody but only weakly by the antibodies produced against the linear peptide leading to a divergent outcome between the passive and active immunization.
艾美耳球虫可引发禽球虫病，给家禽业造成巨大经济损失。因此，抗球虫药物和疫苗已被用于对抗这种毁灭性疾病。一种基于配子体重组蛋白的有效疫苗在成本、人力和伦理（无需动物实验）方面将非常有用。使用一种针对柔嫩艾美耳球虫配子体抗原56（EtGAM56）的小鼠源单克隆抗体对感染柔嫩艾美耳球虫的鸡进行腹腔免疫，观察到卵囊排出量减少了78%。对该单克隆抗体识别的表位进行了定位、重组表达并用于免疫鸡（rEtGAM56N）。在rEtGAM56N肌肉注射免疫和寄生虫攻击后，评估粪便卵囊产量、体重增加、病变评分、饲料转化率和血清抗体反应等临床参数，以测试针对柔嫩艾美耳球虫实验性感染的疫苗接种效果。用rEtGAM56N免疫并用柔嫩艾美耳球虫卵囊攻击的鸡对rEtGAM56N肽表现出强烈的抗体反应，但与 mock 对照组相比，对卵囊产量和临床参数（体重增加、病变评分、饲料转化率）没有显著影响。这项研究证明了有效疫苗接种的复杂性。免疫保护性表位可能是一种构象表位，它被小鼠单克隆抗体识别，但被针对线性肽产生的抗体识别较弱，并导致被动免疫和主动免疫之间的不同结果。
