[Molecular cloning of two Rhipicephalus haemaphysaloides haemaphysaloides cathepsin L-like cysteine proteinase gene].

Ticks are obligate ectoparasites and vectors of arboviruses, vickettsiate, spirochetes and parasitil protozoa of humans and domestic animals. Immunological protection of mammalian hosts against tick infestation has been proposed as the most sustainable alternative tick control method to the current use of acaricides. The success of this method is dependent on the identification of key molecules for use as tick vaccine antigens. Proteolytic enzymes are involved in a wide range of cellular processes, thus they can be considered as good target antigens for a tick vaccine. In the present study, we used rapid amplification of cDNA ends protocol and primers that were designed based on the consensus amino acid motifs flanking present in all papain-like cysteine proteinases, to amplify, sequence and characterize two Rhipicephalus haemaphysaloides haemaphysaloides cathepsin L-like cysteine proteinases, named as cysA and cysB. The full length of cysA is 1168bp, encoding a 332 amino acid residue polypeptide with 36.33kD predicted molecular mass; the full length of cysB is 1153bp, encoding a 335 amino acid residue polypeptide with 37.56kD predicted molecular mass. The consensus amino acid motifs flanking presence in both deduced amino acid sequences. And both genes show high sequence homology to other tick cathepsin L-like cysteine proteinase, so they were identified as members of the cysteine proteinase gene family. Expression analysis by RT-PCR revealed that cysA and cysB were expressed differently in different periods of tick development.