2007 Fiscal Year Final Research Report Summary
Development of control methods for tick and tick-borne diseases by functional analyses of midgut tick bioactive molecules
| Project/Area Number |
16380209
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied veterinary science
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| Research Institution | National Agricultural Research Organization |
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Principal Investigator |
TSUJI Natoshi National Agricultural Research Organization, Research Team for Zoonotic Diseases, National Institute of Animal Health, Senior Researcher (70355171)
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| Co-Investigator(Kenkyū-buntansha) |
FUJISAKI Kozo Obihiro University of Agriculture and Veterinary Medicine, National Research Center for Protozoan Diseases, Professor (00292095)
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| Project Period (FY) |
2004 – 2007
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| Keywords | arthropod / tick / pathogen transmission / vector / midgut |
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| Research Abstract |
Ticks must feed only on blood to obtain nutrients. Ticks as vectors are the most important ecto-parasites of domestic animals and are the second-most important vector only to mosquitoes among arthropods that transmit infectious diseases in human. Pathogens, including viruses, bacteria and parasites, are taken up with the blood meal and exposed to a potentially hostile environment in the tick's midgut before invading the epithelium. Vector ticks possess a unique system that enables them to digest large amounts of host blood and to transmit the pathogens to the host, suggesting the existence of evolutionally acquired proteolytic mechanisms. Functional analyses of tick bioactive molecules (TBM) from the midgut of the babesial parasite vector tick Haemaphysalis longicornis were performed.
1. Molecular basis of tick blood feeding and digestion
Several TBMs implicated in blood feeding and digestion. (1) Tick serine proteases contributed to hemolysis, the initial step of hemoglobin digestion. (
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2) Several proteases expressed in the midgut contributed to host hemoglobin digestion, suggesting existence of an enzyme cascade of proteolysis of host blood components. (3) Inhibition of Glutamine: fructose-6-phosphate aminotransferase limits chitin biosynthesis thereby disrupting cuticle growth and peritrophic matrix formation during blood feeding.
2. TMBs play crucial roles in inhibiting the transmission of Babesia parasites
Several TBMs (longicin, longipain and H1Galec) implicated in parasite transmission. (1) longicin which is one of tick defensins has babesiacidal effect. (2) longipain controlled the number of babesia parasites for invasion into the midgut. (3) HIGalec was a possible receptor of parasites in the midgut.
3. Generation of gene-knockdown ticks
We established RNA interference to knockdown longipain mRNA by dsRNA injection in H. longicornis. This method may allow a direct and efficient way of producing and identifying the loss-of-function of targeted genes as a reverse genetic tool. Less
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[Journal Article] RNA interference of cytosolic leucine aminopeptidase reduces fecundity in the hard tick, Haemaphysalis longicornis.2007
Author(s)
Hatta T, Umemiya R, Liao M, Gong H, Harnnoi T, Tanaka M, Miyoshi T, Boldbaatar D, Battsetseg B, Zhou J, Xuan X, Tsuji N, Taylor D, Fujisaki K
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Journal Title
Parasitol Res 100
Pages: 847-854
Description
「研究成果報告書概要(和文)」より
Peer Reviewed
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[Journal Article] RNA interference of cytosolic leucine aminopeptidase reduces fecundity in the hard tick, Haemaphysalis longicornis.2007
Author(s)
Hatta T, Umemiya R, Liao M, Gong H, harnnoi t, Tanaka M, Miyoshi T, Boldbaatar D, Battsetseg B, Zhou J, Xuan X, Tsuji N, Taylor D, Fujisaki K.
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Journal Title
Parasitol Res 100
Pages: 847-854
Description
「研究成果報告書概要(欧文)」より
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[Book] つくばの研究開発情報誌2006
Author(s)
辻 尚利.
Total Pages
2
Publisher
ベクターにおける病原微生物媒介の分子基盤.
Description
「研究成果報告書概要(和文)」より
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