Association of human immune response to Aedes aegypti salivary proteins with dengue disease severity

Abstract

Dengue viruses (DENV; family Flaviviridae, genus Flavivirus) are transmitted by Aedes aegypti mosquitoes and can cause dengue fever (DF), a relatively benign disease, or more severe dengue haemorrhagic fever (DHF). Arthropod saliva contains proteins delivered into the bite wound that can modulate the host haemostatic and immune responses to facilitate the intake of a blood meal. The potential effects on DENV infection of previous exposure to Ae. aegypti salivary proteins have not been investigated. We collected Ae. aegypti saliva, concentrated the proteins and fractionated them by nondenaturing polyacrylamide gel electrophoresis (PAGE). By the use of immunoblots, we analysed reactivity with the mosquito salivary proteins (MSP) of sera from 96 Thai children diagnosed with secondary DENV infections leading either to DF or DHF, or with no DENV infection, and found that different proportions of each patient group had serum antibodies reactive to specific Ae. aegypti salivary proteins. Our results suggest that prior exposure to MSP might play a role in the outcome of DENV infection in humans.

Conflict of interest statement

Disclosures: None of the authors has a potential conflict of interest.

© 2011 Blackwell Publishing Ltd.

Figures

Figure 1. Fractionation of mosquito salivary proteins (MSP) by polyacrylamide gel electrophoresis (PAGE)

Lane 1, molecular markers; Lane 2, Ae. aegypti salivary proteins concentrated with trichloroacetic acid (TCA), fractionated by nondenaturing 10% PAGE and silver stained; approx. sizes in kDa and positions of major MSP are indicated at right.

Figure 2. Reactivity of patients’ sera in immunoblots

Lane 1, molecular markers; Lanes 2 and 3, Immunoblots showing reactivity of 2 different patients’ sera with MSP. Approximate sizes in kDa of immunoreactive proteins shown at right.

Figure 3. Identity of salivary gland homogenate proteins and immunoreactive MSP

A. Lane 1, molecular markers; Lane 2, Salivary gland homogenate fractionated by 10% PAGE and Coomassie blue stained. Bands indicated by arrows were excised from the gel for MS analysis. B. Lane 1, molecular markers; Lanes 2, 3, 4, Immunoblot analysis of individual proteins excised and eluted from gel and fractionated by PAGE using pooled patient sera. Lane 2 = 30 kDa, Lane 3 = 36 kDa, Lane 4 = 68 kDa.