Immunization of mice with recombinant P27/30 protein confers protection against hard tick Haemaphysalis longicornis (Acari: Ixodidae) infestation

The success of immunological control methods is dependent upon the use of potential key antigens as tick vaccine candidates. Previously, we cloned a gene encoding 27 kDa and 30 kDa proteins (P27/30) of Haemaphysalis longicornis, and identified the P27/30 is a troponin I-like protein. In this study, the recombinant P27/30 (rP27/30) expressed in Escherichia coli was used to immunize mice and the mice were challenge-infested with ticks at different developmental stages of the same species. The rP27/30 protein stimulated a specific protective anti-tick immune response in mice, evidenced by the statistically significant longer pre-feeding periods in adult ticks. Furthermore, significantly longer feeding periods were noted in both larval and adult ticks. On the other hand, only larval ticks exhibited low attachment rates (31.1%). Immunization of mice with rP27/30 protein confers protection against hard tick Haemaphysalis longicornis infestation. These results demonstrated that the rP27/30 protein might be a useful vaccine candidate antigen for biological control of ticks.

Immunization effect of recombinant P27/30 protein expressed in Escherichia coli against the hard tick Haemaphysalis longicornis (Acari: Ixodidae) in rabbits

We investigated the induction of resistance to Haemaphysalis longicornis infestation in rabbits that had been immunized with recombinant H. longicornis P27/30 protein. The success of immunological control methods is dependent upon the use of potential key antigens as tick vaccine candidates. Previously, we cloned a gene encoding 27 kDa and 30 kDa proteins (P27/30) of H. longicornis, and identified P27/30 as a troponin I-like protein. In this study, rabbits that were immunized with recombinant P27/30 expressed in Escherichia coli showed the statistically significant longer feeding duration for larval and adult ticks (P< 0.05), low engorgement rates in larval ticks (64.4%), and an apparent reduction in egg weights, which suggest that H. longicornis P27/30 protein is a potential candidate antigen for a tick vaccine. These results demonstrated that the recombinant P27/30 protein might be a useful vaccine candidate antigen for biological control of H. longicornis.