Characterization of an 84 kDa protein inducing an immediate hypersensitivity reaction in rabbits sensitized to Haemaphysalis longicornis ticks

An immunogenic 84 kDa protein was isolated and purified from whole tick ext racts of Haemaphysalis longicornis larvae by a combination of ion exchange, reverse phase and hydrophobic interaction chromatographies. The protein, w hen injected intradermally into rabbits exposed to repeated tick feeding, i nduces an immediate cutaneous hypersensitivity reaction. It has been purifi ed to homogeneity as shown by sodium dodecyl sulphate polyacrylamide gel el ectrophoresis and silver staining. Amino acid sequences for two peptides de rived from proteolytic cleavage of p84 were scanned against known proteins on the SWISS-PROT database. A 7 residue motif, ISGWGNT present in one of th e two peptides appeared conserved in both vertebrate and invertebrate tryps in-like serine proteinases, while another 7 amino acid motif, HVPAGQI prese nt in the second peptide showed homology to an Escherichia coli ATP-binding protein. We have discussed our findings in relation to isolation and chara cterization of target antigens for tick vaccine candidates. (C) 2000 Elsevi er Science B.V. All rights reserved.