Haemonchus contortus transthyretin domain-containing protein (HcTTR) with 136 amino acids belongs to a transthyretin-like (TTL) family member. In our previous study, it was reported that HcTTR was a novel antagonist of the goat cytokine Interleukin 4 (IL-4), and was involved in the regulation of host immune responses, implying that it might be applied for therapeutic strategies or vaccine development against the infection of H. contortus. Thus, the protective capacities of HcTTR against H. contortus infections via active and passive immunization trials were examined. For the passive protection trials, H. contortus-infected goats were intravenously immunized twice with 5 mg of total IgG containing anti-rHcTTR goat polyclonal antibodies. The results showed that the significant rates of reduction in egg shedding and worm burden was 58.12% and 64.61%, respectively, as compared with the positive control group. For the active protection trials, local goats were vaccinated twice with 500 μg of recombinant HcTTR to generate antigen-specific circulating antibodies, resulting in 63.7% reduction in eggs shedding and 66.4% reduction in worm burdens after H. contortus challenge. In both passive and active trials, the immunized goats displayed higher mucosal IgA levels and less anaemic compared to the challenged positive controls. Pen trials indicated that HcTTR generated partial immune protective effects against H. contortus challenge and it could be a promising vaccine candidate for development of effective strategy to control H. contortus.

中文翻译：

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捻转血矛线虫含甲状腺素蛋白结构域蛋白（HcTTR）：抗捻转血矛线虫感染的有希望的候选疫苗。

含有136个氨基酸的弯曲变形杆菌含有转甲状腺素蛋白结构域蛋白（HcTTR）属于类转甲状腺素蛋白（TTL）家族成员。在我们先前的研究中，据报道，HcTTR是山羊细胞因子白介素4（IL-4）的新型拮抗剂，并参与宿主免疫应答的调节，这暗示它可能被用于治疗策略或针对弯曲杆菌的感染。因此，通过主动和被动免疫试验，研究了HcTTR对Contortus感染的保护能力。对于被动保护试验，用5 mg含抗rHcTTR山羊多克隆抗体的总IgG静脉注射两次感染了弯曲杆菌的山羊。结果表明，减少鸡蛋脱落和蠕虫负担的显着率分别为58.12％和64.61％，与阳性对照组相比。对于主动保护试验，用500μg重组HcTTR疫苗对本地山羊进行了两次疫苗接种，以产生抗原特异性循环抗体，从而在对弓形虫攻击后减少了63.7％的卵脱落和66.4％的蠕虫负担。在被动和主动试验中，与挑战的阳性对照相比，免疫山羊显示出更高的粘膜IgA水平和更少的贫血。笔试验表明，HcTTR产生了对抗弯曲变形杆菌挑战的部分免疫保护作用，它可能是开发控制弯曲变形杆菌有效策略的有希望的候选疫苗。局部山羊用500μg重组HcTTR接种了两次疫苗以产生抗原特异性循环抗体，从而导致了在捻转血吸虫攻击后，卵的脱落减少了63.7％，蠕虫负担减少了66.4％。在被动和主动试验中，与挑战的阳性对照相比，免疫山羊显示出更高的粘膜IgA水平和更少的贫血。笔试验表明，HcTTR产生了对抗弯曲变形杆菌挑战的部分免疫保护作用，它可能是开发控制弯曲变形杆菌有效策略的有希望的候选疫苗。局部山羊用500μg重组HcTTR接种了两次疫苗以产生抗原特异性循环抗体，从而导致了在捻转血吸虫攻击后，卵的脱落减少了63.7％，蠕虫负担减少了66.4％。在被动和主动试验中，与挑战的阳性对照相比，免疫山羊显示出更高的粘膜IgA水平和更少的贫血。笔试验表明，HcTTR产生了对抗弯曲变形杆菌挑战的部分免疫保护作用，它可能是开发控制弯曲变形杆菌有效策略的有希望的候选疫苗。与攻击阳性对照相比，免疫山羊显示出更高的粘膜IgA水平和更少的贫血。笔试验表明，HcTTR产生了对抗弯曲变形杆菌挑战的部分免疫保护作用，它可能是开发控制弯曲变形杆菌有效策略的有希望的候选疫苗。与攻击的阳性对照相比，免疫山羊显示出更高的粘膜IgA水平和更少的贫血。笔试验表明，HcTTR产生了对抗弯曲变形杆菌挑战的部分免疫保护作用，它可能是开发控制弯曲变形杆菌有效策略的有希望的候选疫苗。