Immunogenic potential of Rhipicephalus (Boophilus) microplus aquaporin 1 against Rhipicephalus sanguineus in domestic dogs

Abstract This study evaluated a recombinant aquaporin 1 protein of Rhipicephalus (Boophilus) microplus (RmAQP1) as antigen in a vaccine against R. sanguineus. Five dogs were immunized with RmAQP1 (10 µg) + adjuvant (Montanide) (G1), and five were inoculated with adjuvant only (G2), three times. Twenty-one days after the last immunization, animals of both groups were challenged with R. sanguineus larvae, nymphs and adults, and their biotic potential was compared. Blood samples were collected before each immunization and every 28 days after the last immunization for 10 weeks. Serum antibody titers (IgG) were assessed by ELISA. We observed that: engorgement period of adult females from G1 was 12% shorter than G2; larvae from G1 had 8.7% longer engorgement period than G2 and weighed 7.2% less; nymphs from G1 had 4.5% shorter engorgement period than G2 and weighed 3.6% less; although the antibody titers increased following the second immunization, they rapidly decreased after the third immunization. Results indicated low immunoprotection of RmAQP1 against adult R. sanguineus ticks, and possible efficacy on larvae and nymphs fed on immunized dogs. Further studies should be performed for a full evaluation of the immunoprotection of RmAQP1 against R. sanguineus infestations in dogs.

摘要 本研究以微小牛蜱（*Rhipicephalus (Boophilus) microplus*）重组水通道蛋白1（Aquaporin 1, AQP1，缩写RmAQP1）为抗原，评估其在抗血红扇头蜱（*R. sanguineus*）疫苗中的应用效果。将10只实验犬随机分为两组，每组5只：G1组以10 μg RmAQP1联合蒙坦尼德（Montanide）佐剂免疫，G2组仅注射蒙坦尼德佐剂，两组均完成3次免疫。末次免疫后21天，对两组实验犬分别进行血红扇头蜱幼虫、若虫及成虫攻虫，比较两组蜱虫的生物潜能。分别于每次免疫前、末次免疫后每28天采集血液样本，持续10周，采用酶联免疫吸附试验（Enzyme-Linked Immunosorbent Assay, ELISA）检测血清IgG抗体滴度。实验结果显示：G1组雌成蜱的饱血时长较G2组缩短12%；G1组幼虫的饱血时长较G2组延长8.7%，且体重降低7.2%；G1组若虫的饱血时长较G2组缩短4.5%，体重降低3.6%；尽管第二次免疫后抗体滴度有所升高，但第三次免疫后抗体滴度迅速下降。结果表明，RmAQP1对血红扇头蜱成虫的免疫保护效果较弱，但其对免疫犬体内寄生的幼虫和若虫可能具备一定防控潜力。后续需开展进一步研究，以全面评估RmAQP1对犬血红扇头蜱侵染的免疫保护作用。