title: Characterization of the anticoagulant protein Rhipilin-1 from the Rhipicephalus haemaphysaloides tick.
abstract: To understand the molecular mechanism of tick blood feeding, an anticoagulant protein, Rhipilin-1, was identified in the tick Rhipicephalus haemaphysaloides. The cDNA sequence of Rhipilin-1 is 620bp, and it encodes a deduced 164 amino acid protein with a size of 18kDa. Bioinformatic analysis shows that Rhipilin-1 belongs to the Kunitz-type family of inhibitors, containing one Kunitz domain with high homology to the tissue factor pathway inhibitor (TFPI). The recombinant protein expressed in Escherichia coli delayed normal clotting of rabbit plasma both in the recalcification time (RT) and the activated partial thromboplastin time (APTT) tests. Using RT-PCR, mRNA transcripts of Rhipilin-1 were detected in fed but not in unfed ticks. Disruption of the Rhipilin-1 gene with RNAi led to a 52.7% decrease in the tick attachment rate 24h after introduction in the rabbit ears and a 21.9% decrease in the average engorged body weight of ticks. These results indicate that Rhipilin-1 is a novel anticoagulant protein involved in tick blood feeding with possible future application as a vaccine candidate. The discovery of Rhipilin-1 is the first report on anticoagulant genes in this species of tick.
authors.affiliation: Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, No. 518 Ziyue Road, Minhang District, Shanghai, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Gao
authors.forename: Lei
authors.initials: L
authors.lastname: Shi
authors.forename: Yongzhi
authors.initials: Y
authors.lastname: Zhou
authors.forename: Jie
authors.initials: J
authors.lastname: Cao
authors.forename: Houshuang
authors.initials: H
authors.lastname: Zhang
authors.forename: Jinlin
authors.initials: J
authors.lastname: Zhou
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000925:Anticoagulants / Q000737:chemistry* / Q000378:metabolism; D001483:Base Sequence; D001777:Blood Coagulation; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D008074:Lipoproteins / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011817:Rabbits; D011994:Recombinant Proteins / Q000276:immunology / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D048494:Rhipicephalus / Q000235:genetics / Q000276:immunology* / Q000378:metabolism
chemical_list: D000925:Anticoagulants; D018076:DNA, Complementary; D008074:Lipoproteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; C051928:lipoprotein-associated coagulation inhibitor