title: Amblyomma americanum tick saliva insulin-like growth factor binding protein-related protein 1 binds insulin but not insulin-like growth factors.
abstract: Silencing Amblyomma americanum insulin-like growth factor binding protein-related protein 1 (AamIGFBP-rP1) mRNA prevented ticks from feeding to repletion. In this study, we used recombinant (r)AamIGFBP-rP1 in a series of assays to obtain further insight into the role(s) of this protein in tick feeding regulation. Our results suggest that AamIGFBP-1 is an antigenic protein that is apparently exclusively expressed in salivary glands. We found that both males and females secrete AamIGFBP-rP1 into the host during feeding and confirmed that female ticks secrete this protein from within 24-48 h after attachment. Our data suggest that native AamIGFBP-rP1 is a functional insulin binding protein in that both yeast- and insect cell-expressed rAamIGFBP-rP1 bound insulin, but not insulin-like growth factors. When subjected to anti-blood clotting and platelet aggregation assays, rAamIGFBP-rP1 did not have any effect. Unlike human IGFBP-rP1, which is controlled by trypsinization, rAamIGFBP-rP1 is resistant to digestion, suggesting that the tick protein may not be under mammalian host control at the tick feeding site. The majority of tick-borne pathogens are transmitted 48 h after the tick has attached. Thus, the demonstrated antigenicity and secretion into the host within 24-48 h of the tick starting to feed makes AamIGFBP-rP1 an attractive target for antitick vaccine development.
authors.affiliation: Department of Veterinary Pathobiology, Texas A&M University, College Station, TX, USA.
authors.forename: Ž M
authors.initials: ŽM
authors.lastname: Radulović
authors.affiliation: Department of Veterinary Pathobiology, Texas A&M University, College Station, TX, USA.
authors.forename: L M
authors.initials: LM
authors.lastname: Porter
authors.affiliation: Department of Veterinary Pathobiology, Texas A&M University, College Station, TX, USA.
authors.forename: T K
authors.initials: TK
authors.lastname: Kim
authors.affiliation: Department of Veterinary Pathobiology, Texas A&M University, College Station, TX, USA.
authors.forename: M
authors.initials: M
authors.lastname: Bakshi
authors.affiliation: Department of Veterinary Pathobiology, Texas A&M University, College Station, TX, USA.
authors.forename: A
authors.initials: A
authors.lastname: Mulenga
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000941:Antigens / Q000276:immunology / Q000378:metabolism* / Q000494:pharmacology; D060829:Arthropod Proteins / Q000276:immunology / Q000378:metabolism* / Q000494:pharmacology; D001777:Blood Coagulation / Q000187:drug effects; D002417:Cattle; D005260:Female; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D018969:Insulin-Like Growth Factor Binding Proteins / Q000276:immunology / Q000378:metabolism*; D026863:Ixodidae / Q000276:immunology / Q000378:metabolism*; D007915:Lepidoptera; D008297:Male; D008969:Molecular Sequence Data; D010843:Pichia; D010974:Platelet Aggregation / Q000187:drug effects; D011485:Protein Binding; D011817:Rabbits / Q000469:parasitology; D011994:Recombinant Proteins / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D012463:Saliva / Q000378:metabolism; D061987:Sf9 Cells; D013002:Somatomedins / Q000378:metabolism*
chemical_list: D000941:Antigens; D060829:Arthropod Proteins; D007328:Insulin; D018969:Insulin-Like Growth Factor Binding Proteins; D011994:Recombinant Proteins; D013002:Somatomedins; C102529:insulin-like growth factor binding protein-related protein 1
keywords: Amblyomma americanum; insulin-like growth factor binding protein-related protein 1; tick saliva