title: A set of serine proteinase paralogs are required for blood-digestion in the ixodid tick Haemaphysalis longicornis.
abstract: We present evidence demonstrating that genes encoding enzymes essential for successful blood-feeding are differentially induced in the midgut of the hard tick Haemaphysalis longicornis. Three serine proteinase genes (HlSP, HlSP2 and HlSP3) isolated from H. longicornis midgut exhibit protein sequence similarity with other trypsin-like serine proteinases reported from arthropods and vertebrate animal species. The endogenous enzymes were mainly detected in the midgut epithelial cells and in the lumen of an adult tick. The recombinant enzymes expressed in Escherichia coli efficiently hydrolyzed synthetic substrates specific for serine proteinases over a broad range of pH and temperature values. Notably, the transcript levels of HlSP2 and HlSP3 were detected to significantly increase at 96 h post infestation, while the transcript of HlSP was induced in the earlier stage of blood-feeding. Further, silencing of HlSP, HlSP2 and HlSP3 genes by RNA interference led to a significant reductions in the engorged tick body weight, suggesting synergetic roles of these serine proteinases in blood-feeding and digestion.
authors.affiliation: Laboratory of Parasitic Diseases, National Institute of Animal Health, National Agriculture and Food Research Organization, 3-1-5 Kannondai, Tsukuba, Ibaraki 305-0856, Japan.
authors.forename: Takeharu
authors.initials: T
authors.lastname: Miyoshi
authors.forename: Naotoshi
authors.initials: N
authors.lastname: Tsuji
authors.forename: M Khyrul
authors.initials: MK
authors.lastname: Islam
authors.forename: M Abdul
authors.initials: MA
authors.lastname: Alim
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hatta
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Huang
authors.forename: Kozo
authors.initials: K
authors.lastname: Fujisaki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001769:Blood / Q000378:metabolism*; D003001:Cloning, Molecular; D004064:Digestive System / Q000201:enzymology; D005247:Feeding Behavior; D026863:Ixodidae / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D034622:RNA Interference; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; C432950:HLSG-1 protein, Haemaphysalis longicornis; C432951:HLSG-2 protein, Haemaphysalis longicornis; D012697:Serine Endopeptidases