Collagen-binding protein, Aegyptin, regulates probing time and blood feeding success in the dengue vector mosquito, Aedes aegypti.
Mosquito salivary glands have important roles in blood feeding and pathogen transmission. However, the biological relevance of many salivary components has yet to be determined. Aegyptin, a secreted salivary protein from Aedes aegypti, binds collagen and inhibits platelet aggregation and adhesion. We used a transgenic approach to study the relevance of Aegyptin in mosquito blood feeding. Aedes aegypti manipulated genetically to express gene-specific inverted-repeat RNA sequences exhibited significant reductions in Aegyptin mRNA accumulation (85-87%) and protein levels (>80-fold) in female mosquito salivary glands. Transgenic mosquitoes had longer probing times (78-300 s, P < 0.0001) when feeding on mice compared with controls (15-56 s), feeding success was reduced, and those feeding took smaller blood meals. However, no differences in feeding success or blood meal size were found in membrane feeding experiments using defibrinated human blood. Salivary gland extracts from transgenic mosquitoes failed to inhibit collagen-induced platelet aggregation in vitro. Reductions of Aegyptin did not affect salivary ADP-induced platelet aggregation inhibition or disturb anticlotting activities. Our results demonstrate the relevance of Aegyptin for A. aegypti blood feeding, providing further support for the hypothesis that platelet aggregation inhibition is a vital salivary function in blood feeding arthropods. It has been suggested that the multiple mosquito salivary components mediating platelet aggregation (i.e., Aegyptin, apyrase, D7) represent functional redundancy. Our findings do not support this hypothesis; instead, they indicate that multiple salivary components work synergistically and are necessary to achieve maximum blood feeding efficiency.
Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, Rockville, MD 20852;
Andrezza Campos
AC
Chagas
Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, Rockville, MD 20852;
José Luis
JL
Ramirez
Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697-3900; and.
Nijole
http://orcid.org/0000-0002-0862-0349
N
Jasinskiene
Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697-3900; andDepartment of Microbiology and Molecular Genetics, University of California, Irvine, CA 92697-4025.
Anthony A
AA
James
Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, Rockville, MD 20852;
José M C
JM
Ribeiro
Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697-3900; and ecalvo@niaid.nih.gov omarinot@uci.edu.
Osvaldo
O
Marinotti
Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, Rockville, MD 20852; ecalvo@niaid.nih.gov omarinot@uci.edu.
Eric
E
Calvo
D000330:Aedes / Q000235:genetics* / Q000502:physiology / Q000821:virology*; D000818:Animals; D030801:Animals, Genetically Modified; D000918:Antibody Specificity; D001483:Base Sequence; D001777:Blood Coagulation / Q000502:physiology; D001798:Blood Proteins / Q000502:physiology; D003094:Collagen / Q000378:metabolism; D003716:Dengue Virus / Q000235:genetics*; D005247:Feeding Behavior; D005260:Female; D020868:Gene Silencing; D006801:Humans; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D010974:Platelet Aggregation / Q000502:physiology; D011817:Rabbits; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D012463:Saliva / Q000378:metabolism; D012471:Salivary Proteins and Peptides / Q000235:genetics* / Q000378:metabolism
D001798:Blood Proteins; D019476:Insect Proteins; D011994:Recombinant Proteins; D012471:Salivary Proteins and Peptides; C583517:aegyptin protein, Aedes aegypti; C024875:platelet adhesion inhibitor; D003094:Collagen
RNAi; evolution; hematophagy; saliva; transgenesis