VACCINES AGAINST BLOODSUCKING ARTHROPODS

This paper provides selected personal insights on the development of v accines against blood-sucking arthropods, with particular emphasis on vaccines against ticks. The emergence of novel or concealed antigens o f haematophagous ectoparasites as candidate vaccine antigens is review ed and the effect of feeding by the parasite on the expression of prot ective antigens is considered. The distribution of protective antigens through life cycle stages, the stage of the life cycle targeted by pr otective responses, and the nature of these responses, are commented o n briefly. Concealed antigens of the gut, including the peritrophic me mbrane, and other internal organs, are evaluated for the role they pla y in induction of immunity artificially. Some of the work carried out to purify and characterise protective antigens of tick guts is describ ed. A commentary is developed on vaccines that combine both ''conceale d'' and ''exposed'' antigens. Some of the problems associated with the infestation and challenge of vaccinated hosts in the field are identi fied and the delivery of parasite antigens as vaccines that are both p rotective and ''user-friendly'' is emphasised as a major problem to be solved.