Collagen-binding protein, Aegyptin, regulates probing time and blood feeding success in the dengue vector mosquito, Aedes aegypti

Abstract

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 genespecific 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.hematophagy | evolution | saliva | transgenesis | RNAi A edes aegypti, the main vector of dengue, chikungunya, and yellow fever viruses, is an anautogenous mosquito that requires a blood meal for egg development. Female mosquitoes probe the skin of a suitable vertebrate host to acquire a blood meal. Hematophagy (blood feeding) to repletion usually takes from seconds to a few minutes (1). The stylets used to pierce the vascular beds of the vertebrate hosts cause local damage that triggers host hemostatic responses.Primary hemostasis is characterized by vascular contraction, platelet adhesion, and formation of a soft aggregate plug that begins immediately after endothelial disruption. Injury causes temporary local contraction of vascular smooth muscle. Vasoconstriction slows blood flow, enhancing platelet adhesion and activation. The soft platelet plug is stabilized to form a clot during secondary hemostasis (2, 3). Hematophagic arthropods have evolved a complex mixture of salivary components that counteract platelet aggregation, blood coagulation, vasoconstriction, and inflammation to overcome this efficient and redundant vertebrate hemostatic system (4-6).Aedes aegypti, Anopheles stephensi, and Simulim nigrimanum express salivary collagen-binding proteins that prevent collagenin...

Mosquito salivary allergen Aed a 3: cloning, comprehensive molecular analysis, and clinical evaluation

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RNA Interference for Mosquito and Mosquito-Borne Disease Control

“…In Ae. aegypti , suppression of the aegyptin gene results in drastically reduced blood meal uptake and egg output [17]. Additionally RNAi silencing of circadian rhythm ( timeless , chryptochrome 1 , takeout 1–3 ) odorant receptor genes have been linked to reduced blood feeding success in An.…”

“…With hundreds of documented effective RNAi triggers targeting mosquito and pathogen genes, there is an expansive arsenal of anti-vector and anti-pathogen targets that could be harnessed for mosquito and mosquito-borne disease control strategies. RNAi experiments in a number of Aedes , Anopheles , Culex , and Armigeres disease vector species have resulted in disruption of processes including: morphogenesis, olfaction for host seeking and oviposition, blood feeding, fertility, fecundity, and survival [10,11,12,13,14,15,16,17,18,19]. …”

<b><i>Aedes communis</i></b> Reactivity Is Associated with Bee Venom Hypersensitivity: An in vitro and in vivo Study

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