Analysis in a murine model points to IgG responses against the 34k2 salivary proteins from Aedes albopictus and Aedes aegypti as novel promising candidate markers of host exposure to Aedes mosquitoes

Abstract

BackgroundAedes 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 findingsGroups 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/significanceOur 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.

IgG Antibody Responses to the Aedes albopictus 34k2 Salivary Protein as Novel Candidate Marker of Human Exposure to the Tiger Mosquito

“…albopictus salivary gland protein extracts (SGE) and to the recombinant Ae. albopictus salivary protein al34k2 (Buezo Montero et al, 2019 ). Considering that male volunteers were largely predominant, and to make sure not to introduce any bias, we preliminarily compared IgG responses to SGE in males versus females and found no statistically significant difference ( Supplementary Figure 2A ); similar results were obtained comparing anti-al34k2 IgG responses in the two sexes.…”

“…The Ae. albopictus al34k2 salivary protein was expressed and purified as previously described (Buezo Montero et al, 2019 ).…”

“…Enzyme-linked immunosorbent assays (ELISA) were essentially performed as previously described (Rizzo et al, 2011a , 2014a ; Buezo Montero et al, 2019 ). Briefly, flat-bottom 96-well plates (Nunc MaxiSorp, 442404) were coated for 3 h at room temperature (RT) with 50 μl of either Ae.…”

“…albopictus and in a single human donor hyperimmune to Ae. albopictus saliva (Buezo Montero et al, 2019 ). Moreover, mice immunized by exposure to bites of Ae.…”

Aedes albopictus D7 Salivary Protein Prevents Host Hemostasis and Inflammation

“…Antibodies against Ae. albopictus salivary proteins are currently being used as markers to monitor host exposure to specific mosquito bites [ 20 , 21 , 22 ]. However, only a few studies have been done to identify and characterize the Ae.…”