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Aedes albopictus D7 Salivary Protein Prevents Host Hemostasis and Inflammation.

ABSTRACT: Mosquitoes inject saliva into the host skin to facilitate blood meal acquisition through active compounds that prevent hemostasis. D7 proteins are among the most abundant components of the mosquito saliva and act as scavengers of biogenic amines and eicosanoids. Several members of the D7 family have been characterized at the biochemical level; however, none have been studied thus far in Aedes albopictus, a permissive vector for several arboviruses that causes extensive human morbidity and mortality. Here, we report the binding capabilities of a D7 long form protein from Ae. albopictus (AlboD7L1) by isothermal titration calorimetry and compared its model structure with previously solved D7 structures. The physiological function of AlboD7L1 was demonstrated by ex vivo platelet aggregation and in vivo leukocyte recruitment experiments. AlboD7L1 binds host hemostasis agonists, including biogenic amines, leukotrienes, and the thromboxane A2 analog U-46619. AlboD7L1 protein model predicts binding of biolipids through its N-terminal domain, while the C-terminal domain binds biogenic amines. We demonstrated the biological function of AlboD7L1 as an inhibitor of both platelet aggregation and cell recruitment of neutrophils and eosinophils. Altogether, this study reinforces the physiological relevance of the D7 salivary proteins as anti-hemostatic and anti-inflammatory molecules that help blood feeding in mosquitoes.

SUBMITTER: Martin-Martin I

PROVIDER: S-EPMC7601585 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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<i>Aedes albopictus</i> D7 Salivary Protein Prevents Host Hemostasis and Inflammation.

Martin-Martin Ines I Smith Leticia Barion LB Chagas Andrezza Campos AC Sá-Nunes Anderson A Shrivastava Gaurav G Valenzuela-Leon Paola Carolina PC Calvo Eric E

Biomolecules 20200927 10

Mosquitoes inject saliva into the host skin to facilitate blood meal acquisition through active compounds that prevent hemostasis. D7 proteins are among the most abundant components of the mosquito saliva and act as scavengers of biogenic amines and eicosanoids. Several members of the D7 family have been characterized at the biochemical level; however, none have been studied thus far in <i>Aedes albopictus</i>, a permissive vector for several arboviruses that causes extensive human morbidity and ...[more]

PMID: 32992542

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Project description:BACKGROUND:Aedes mosquitoes are vectors of arboviral diseases of great relevance for public health. The recent outbreaks of dengue, Zika, chikungunya and the rapid worldwide spreading of Aedes albopictus emphasize the need for improvement of vector surveillance and control. Host antibody response to mosquito salivary antigens is emerging as a relevant additional tool to directly assess vector-host contact, monitor efficacy of control interventions and evaluate risk of arboviral transmission. METHODOLOGY/PRINCIPAL FINDINGS:Groups of four BALB/c mice were immunized by exposure to bites of either Aedes albopictus or Aedes aegypti. The 34k2 salivary proteins from Ae. albopictus (al34k2) and Ae. aegypti (ae34k2) were expressed in recombinant form and Ae. albopictus salivary peptides were designed through B-cell epitopes prediction software. IgG responses to salivary gland extracts, peptides, al34k2 and ae34k2 were measured in exposed mice. Both al34k2 and ae34k2, with some individual and antigen-specific variation, elicited a clearly detectable antibody response in immunized mice. Remarkably, the two orthologous proteins showed very low level of immune cross-reactivity, suggesting they may eventually be developed as species-specific markers of host exposure. The al34k2 immunogenicity and the limited immune cross-reactivity to ae34k2 were confirmed in a single human donor hyperimmune to Ae. albopictus saliva. CONCLUSIONS/SIGNIFICANCE:Our study shows that exposure to bites of Ae. albopictus or Ae. aegypti evokes in mice species-specific IgG responses to al34k2 or ae34k2, respectively. Deeper understanding of duration of antibody response and validation in natural conditions of human exposure to Aedes mosquitoes are certainly needed. However, our findings point to the al34k2 salivary protein as a promising potential candidate for the development of immunoassays to evaluate human exposure to Ae. albopictus. This would be a step forward in the establishment of a serological toolbox for the simultaneous assessment of human exposure to Aedes vectors and the pathogens they transmit.

Project description:BackgroundThe rapid worldwide spreading of Aedes aegypti and Aedes albopictus is expanding the risk of arboviral diseases transmission, pointing out the urgent need to improve monitoring and control of mosquito vector populations. Assessment of human-vector contact, currently estimated by classical entomological methods, is crucial to guide planning and implementation of control measures and evaluate transmission risk. Antibody responses to mosquito genus-specific salivary proteins are emerging as a convenient complementary tool for assessing host exposure to vectors. We previously showed that IgG responses to the Ae. albopictus 34k2 salivary protein (al34k2) allow detection of seasonal and geographic variation of human exposure to the tiger mosquito in two temperate areas of Northeast Italy. The main aim of this study was to confirm and extend these promising findings to tropical areas with ongoing arboviral transmission.MethodsIgG responses to al34k2 and to the Ae. aegypti orthologous protein ae34k2 were measured by ELISA in cohorts of subjects only exposed to Ae. albopictus (Réunion Island), only exposed to Ae. aegypti (Bolivia) or unexposed to both these vectors (North of France).Results and conclusionAnti-al34k2 IgG levels were significantly higher in sera of individuals from Réunion Island than in unexposed controls, indicating that al34k2 may be a convenient and reliable proxy for whole saliva or salivary gland extracts as an indicator of human exposure to Ae. albopictus. Bolivian subjects, exposed to bites of Ae. aegypti, carried in their sera IgG recognizing the Ae. albopictus al34k2 protein, suggesting that this salivary antigen can also detect, even though with low sensitivity, human exposure to Ae. aegypti. On the contrary, due to the high background observed in unexposed controls, the recombinant ae34k2 appeared not suitable for the evaluation of human exposure to Aedes mosquitoes. Overall, this study confirmed the suitability of anti-al34k2 IgG responses as a specific biomarker of human exposure to Ae. albopictus and, to a certain extent, to Ae. aegypti. Immunoassays based on al34k2 are expected to be especially effective in areas where Ae. albopictus is the main arboviral vector but may also be useful in areas where Ae. albopictus and Ae. aegypti coexist.

Dataset Information

Aedes albopictus D7 Salivary Protein Prevents Host Hemostasis and Inflammation.

Publications

<i>Aedes albopictus</i> D7 Salivary Protein Prevents Host Hemostasis and Inflammation.

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