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Haemonchus contortus transthyretin domain - containing protein (HcTTR): A promising vaccine candidate against Haemonchus contortus infection

Li Charles Z., Xiaowei Tian, Mingmin Lu, Caiwen Jia, Yongqian Bu, Kalibixiati Aimulajiang, Yang Zhang, Charles Li, Ruofeng Yan, Lixin Xu, Xiaokai Song, Xiangrui Li
Veterinary parasitology 2020 v.279 pp. 109045
Haemonchus contortus, amino acids, anemia, antagonists, eggs, goats, immune response, immunization, immunoglobulin A, immunoglobulin G, interleukin-4, intravenous injection, polyclonal antibodies, prealbumin, protective effect, vaccine development, vaccines
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.