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Serine proteinase inhibitor families in Rhipicephalus microplus

Kurscheid, S., Rodriguez-Valle, M., Guerrero, F., Lew, A. and Bellgard, M. (2008) Serine proteinase inhibitor families in Rhipicephalus microplus. In: VIth International Conference on Ticks and Tick-Borne Pathogens, 21 - 26 September 2008, Buenos Aires, Argentina.

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The search for Rhipicephalus (Boophilus) microplus (cattle tick) vaccine candidates is a high research priority in Australia. Serine proteinase inhibitors (serpins) are implicated as potential vaccine candidates due to their ability to interfere with host homeostasis as a potent anti-coagulant. Serpins have been identified in Amblyomma, Ixodes, Haemaphysalis and Rhipicephalus spp., with 6 previously identified in R. microplus. The BmiGI2 R. microplus EST database of 13,643 consensus sequences and singletons was mined using Pfam domain Pf00079 (Serpin) to identify putative transcripts. Relative expression of the serpins was determined using RNA from different tick issues (gut, ovaries, salivary glands) and different developmental stages (larvae, nymph, adult male and female) in two step SYBR Green quantitative real time PCR assays. Thirty-five R. microplus serpin transcripts were identified through in silico and transcriptome analyses. These 35 clustered into 9 groups according to their similarity to known serine protease inhibitors from other tick species. Oligonucleotide primers were designed for one transcript representing each of the 9 groups. We demonstrate the up-regulation of different serpins in feeding adult ticks and larval stages based on quantitative real time PCR analysis. This is the first comprehensive study of R. microplus serine proteinase inhibitor family of proteins. We have identified 9 clusters of R. microplus serpins which is consistent with studies undertaken in other tick species. Congruent with the tick serpin nomenclature used to date, we suggest that the R. microplus serpins be named Catspins (Cattle tick serpin) in order to differentiate from host and mammalian serpins. The usefulness of serpins as vaccine candidates for R. microplus warrants further investigation.

Item Type: Conference Item
Murdoch Affiliation(s): Centre for Comparative Genomics
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