A set of serine proteinase paralogs are required for blood-digestion in the ixodid tick Haemaphysalis longicornis

作者：Miyoshi Takeharu; Tsuji Naotoshi^*; Islam M Khyrul; Alim M Abdul; Hatta Takeshi; Huang Xiaohong; Fujisaki Kozo

来源：Parasitology International, 2008, 57(4): 499-505.

DOI：10.1016/j.parint.2008.08.003

• Tick
• Serine proteinase
• Midgut
• Blood-feeding
• RNA interference

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 (HISP, HISP2 and HISP3) 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 HISP2 and HISP3 were detected to significantly increase at 96 h post infestation, while the transcript of HISP was induced in the earlier stage of blood-feeding. Further, silencing of HISP, HISP2 and HISP3 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.

• 出版日期2008-12