State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining 810016, China; College of Agriculture and Animal Husbandry, Qinghai University, Xining 810016, China.
State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining 810016, China; College of Agriculture and Animal Husbandry, Qinghai University, Xining 810016, China; Qinghai Provincial Key Laboratory of Pathogen Diagnosis for Animal Diseases and Green Technical Research for Prevention and Control, Qinghai University, Xining 810016, China.
Vet Parasitol. 2023 Nov;323:110051. doi: 10.1016/j.vetpar.2023.110051. Epub 2023 Oct 10.
Haemaphysalis longicornis can transmit high varieties of tick-borne pathogens (TBPs), and a primary strategy for preventing the transmission of those TBPs is to control ticks. Hemalin, a thrombin inhibitor of the Kunitz-type family and a crucial component in H. longicornis feeding process has been isolated from parthenogentic ticks. This study aimed to evaluate the validity of a recombinant Hemalin (rHlHemalin) vaccination as an anti-tick vaccine against H. longicornis in rabbits to find a new candidate for an effective tick control. In this study, mouse splenocytes were isolated and used to investigate immune responses after rHlHemalin stimulation. The rabbits were vaccinated with the rHlHemalin protein. After tick challenges, body weight at engorgement, egg mass, and the reproductive cycle of H. longicornis were evaluated. To confirm the vaccination, the passive immunization tests of α-rHlHemalin sera were performed. The results showed that the rHlHemalin protein could stimulate cytokine production in mouse splenocytes. Vaccination assay revealed that the periods from tick infestations to egg-hatch in the vaccination group were significantly longer than those in the phosphate buffer saline (PBS) group (P = 0.0003). In addition, the tick body weight at engorgement (P = 0.0019) and egg mass at 10 days after oviposition (P = 0.0232) were higher than those in the PBS group. These findings were consistent with the current passive immunization results and suggest rHlHemalin vaccination extended the reproductive cycle in H. longicornis but did not decrease the body weight at engorgement or weight of egg mass. Therefore, it is debatable whether Hemalin vaccination is highly-effective anti-tick vaccine or not. However, due to the importance of thrombin inhibitors in tick blood feeding and blood digestion, additional inhibitor-based vaccines should be developed aiming to find an effective and environmentally friendly biological strategy to combat ticks.
长角血蜱可以传播多种蜱传病原体（TBPs），预防这些 TBPs 传播的主要策略是控制蜱。从半自然状态下孵化的蜱中分离到血啉，这是一种属于 Kunitz 型家族的凝血酶抑制剂，是长角血蜱取食过程中的关键组成部分。本研究旨在评估重组血啉（rHlHemalin）疫苗作为抗长角血蜱疫苗在兔中的有效性，以寻找一种有效的蜱控制新候选物。在这项研究中，分离小鼠脾细胞，用于研究 rHlHemalin 刺激后的免疫反应。用 rHlHemalin 蛋白对兔子进行疫苗接种。在进行蜱虫挑战后，评估长角血蜱的饱血体重、卵质量和生殖周期。为了确认疫苗接种效果，进行了α-rHlHemalin 血清的被动免疫试验。结果表明，rHlHemalin 蛋白可以刺激小鼠脾细胞产生细胞因子。疫苗接种试验表明，接种组从蜱虫感染到卵孵化的时间明显长于磷酸盐缓冲盐水（PBS）组（P=0.0003）。此外，饱血时蜱虫体重（P=0.0019）和产卵后 10 天的卵质量（P=0.0232）均高于 PBS 组。这些发现与当前的被动免疫试验结果一致，表明 rHlHemalin 疫苗接种延长了长角血蜱的生殖周期，但没有降低饱血时的体重或卵质量。因此，血啉疫苗是否是高效抗蜱疫苗仍存在争议。然而，由于凝血酶抑制剂在蜱吸血和血液消化中的重要性，应该开发额外的抑制剂基疫苗，以寻找一种有效且环保的生物策略来对抗蜱。
