Recent topics of candidate antigens for immunological control of ixodid ticks

Abstract

Ticks have been recognized as harmful parasite since ancient times. At present immunological protection of host against ticks is the most practical and sustainable tick control method, which is more suitable to natural environment compared to the current use of acaricides. Recently, focuses on the development of anti-tick vaccine are the identification, molecular cloning and in vitro production of recombinant protein, responsible for executing key roles in regulating physiology, modulation of host immune response and pathogen transmission via ticks. Among several works, serine protease inhibitors have been thought as one of the most interest vaccine candidates, because serine protease inhibitors are mainly involved in the maintenance of homeostasis. In the current review, we would like to introduce selected examples covering aspects of tick vaccine antigen identification and analyses, because advances in vector molecular biology open new possibilities for vaccine development. In dealing with this subject, contents were mainly divided into tick salivary gland associated molecules (exposed antigens) injected into the host during tick feeding and no salivary gland molecules (concealed antigens). While emerging the fact that serine protease inhibitors belong to either exposed or concealed antigens, the utility of serine protease inhibitors for the candidate vaccine have been discussed separately because of the importance of serine protease inhibitors in the physiology of several organisms including ticks. Advances in tick vaccine development and related subjects are regularly reviewed and in this paper, referred citations of excellence are suggested as additional reading.