Molecular cloning of two Haemaphysalis longicornis cathepsin L-like cysteine proteinase genes

Immunological protection of mammalian hosts against tick infestation has be en proposed as the most sustainable alternative tick control method to the current use of acaricides which has several limitations. The success of thi s method is dependent on the identification of key molecules for use as tic k vaccine antigens. Proteolytic enzymes are involved in a wide range of cel lular processes in eukaryotes such as development regulation and nutrition, thus they can be considered as good target antigens for a tick vaccine. In the present study we used primers designed based on the consensus amino ac id motifs flanking the conserved active sites C-25 and N-175 present in all papain-like cysteine proteinases to amplify by polymerase chain reaction, sequence and characterize two Haemaphysalis longicornis tick cysteine prote inase genes. Based on the nucleotide and deduced amino acid sequences, both genes were identified as members of the cysteine proteinase gene family by presence in their sequences of consensus motifs flanking the conserved act ive sites C-25, H-150 and N-175 that are present in all papain-like cystein e proteinases. Both genes are about 1.2 kb in size and show high sequence h omology predominantly to invertebrate cathepsin L-like cysteine proteinases .