Identification of Aedes aegypti salivary gland proteins interacting with human immune receptor proteins

Abstract

Mosquito saliva proteins modulate the human immune and hemostatic systems and control mosquito-borne pathogenic infections. One mechanism through which mosquito proteins may influence host immunity and hemostasis is their interactions with key human receptor proteins that may act as receptors for or coordinate attacks against invading pathogens. Here, using pull-down assays and proteomics-based mass spectrometry, we identified 11 Ae. aegypti salivary gland proteins (SGPs) (e.g., apyrase, Ae. aegypti venom allergen-1 [AaVA-1], neutrophil stimulating protein 1 [NeSt1], and D7 proteins), that interact with one or more of five human receptor proteins (cluster of differentiation 4 [CD4], CD14, CD86, dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin [DC-SIGN], and Toll-like receptor 4 [TLR4]). We focused on CD4- and DC-SIGN-interacting proteins and confirmed that CD4 directly interacts with AaVA-1, D7, and NeST1 recombinant proteins and that AaVA-1 showed a moderate interaction with DC-SIGN using ELISA. Bacteria responsive protein 1 (AgBR1), an Ae. aegypti saliva protein reported to enhance ZIKV infection in humans but that was not identified in our pull-down assay moderately interacts with CD4 in the ELISA assay. Functionally, we showed that AaVA-1 and NeST1 proteins promoted activation of CD4+ T cells. We propose the possible impact of these interactions and effects on mosquito-borne viral infections such as dengue, Zika, and chikungunya viruses. Overall, this study provides key insight into the vector-host (protein-protein) interaction network and suggests roles for these interactions in mosquito-borne viral infections.

Structural and functional characterization of Aedes aegypti pupal cuticle protein that controls dengue virus infection

“…Previously, we identified mosquito salivary proteins that bind to five human immune receptors (Tassaneetrithep et al, 2003). We proposed models to illustrate the possible “pro‐viral and anti‐viral” impact of salivary gland protein—human host receptors interactions on virus infection (Gavor, Choong, Liu, et al, 2022; Jin et al, 2018). Here, we sought to study the interactions of AaPC with four human receptors, namely, dendritic cell‐specific intercellular adhesion molecule‐3‐grabbing non‐integrin (DC‐SIGN), cluster of differentiation 4 (CD4), Lymphotoxin β Receptor (LTβR), and Leucine rich pentatricopeptide repeat containing protein (LRPPRC).…”

“…Subsequently, the interactions of AaPC with various receptors were studied using the above protocol. After the blocking of overnight coated AaPC plates, 1 μg CD4, LRP, DC‐SIGN, or LTβR in blocking buffer were incubated at 37°C for 2 h. All the extracellular regions of these four receptors were produced as recombinant proteins using the insect baculoviral system (Gavor, Choong, Liu, et al, 2022). Primary antibodies used were rabbit anti‐CD4 monoclonal antibody (Sinobiological, 10400‐R104), rabbit anti‐LRP1 monoclonal antibody (Sinobiological, 102370‐T10), rabbit anti‐DC‐SIGN monoclonal antibody (HRP) (Sinobiologicals, 10200‐R059‐H), or rabbit anti‐LTBR monoclonal antibody (Sinobiological, 107450‐T32).…”

Aedes aegypti salivary gland extract alleviates acute itching by blocking TRPA1 channels

“…In some cases, the salivary molecules responsible for such activities have been elucidated. For example, one protein of the D7 family (scavengers of biogenic amines) was able to inhibit dengue virus infection ( Conway et al, 2016 ); the peptide AeMOPE-1 displays many activities in macrophages and ameliorates experimental colitis ( Lara et al, 2021 ); and many salivary proteins can interact with human receptors involved in immune responses ( Gavor et al, 2022 ).…”

Impact of the microbiome on mosquito-borne diseases

“…Unlike microbes in other tissues, the salivary gland microbiome may affect mosquito-borne diseases by modulating the host immune system. Salivary factors can adjust the immune responses of vertebrate hosts ( Mellink and Vos, 1977 ; Demeure et al, 2005 ; Depinay et al, 2006 ; Gavor et al, 2022 ; Martin-Martin et al, 2022 ), and some arboviruses exploit these mechanisms to evade immune destruction and find host immune cells as their initial replication sites ( Schneider et al, 2010 ; Styer et al, 2011 ; Briant et al, 2014 ; Conway et al, 2014 ; Schmid et al, 2016 ; Sun et al, 2020 ). Therefore, it is possible that mosquito commensal microbes participate in the recruitment of host innate immune cells and the initiation of infection.…”