Human antibody response to Aedes albopictus salivary proteins: a potential biomarker to evaluate the efficacy of vector control in an area of Chikungunya and Dengue Virus transmission

Abstract

Aedes borne viruses represent public health problems in southern countries and threat to emerge in the developed world. Their control is currently based on vector population control. Much effort is being devoted to develop new tools to control such arbovirus. Recent findings suggest that the evaluation of human antibody (Ab) response to arthropod salivary proteins is relevant to measuring the level of human exposure to mosquito bites. Using an immunoepidemiological approach, the present study aimed to assess the usefulness of the salivary biomarker for measuring the efficacy of Ae. albopictus control strategies in La Reunion urban area. The antisaliva Ab response of adult humans exposed to Ae. albopictus was evaluated before and after vector control measures. Our results showed a significant correlation between antisaliva Ab response and the level of exposure to vectors bites. The decrease of Ae. albopictus density has been detected by this biomarker two weeks after the implementation of control measures, suggesting its potential usefulness for evaluating control strategies in a short time period. The identification of species specific salivary proteins/peptides should improve the use of this biomarker.

Figure 1

Evolution of entomological indices and rainfall for the studied period, Reunion Island, 2010. The entomological data of exposure to Ae. albopictus were presented as density of Ae. albopictus adult population (dotted line) and Breteau index (solid line, dark triangle) in the studied households. The daily records of rainfall intensity in the studied site (grey line, dark point) are presented according to the time-points. The timing of vector control intervention (deltamethrin spray) is indicated.

Figure 2

Evolution of IgG response to Ae. albopictus SGE before and after vector control intervention, Reunion Island, 2010. Inhabitants of two districts of Saint Denis city were visited just before T0 and then 2, 4, and 6 weeks after vector control. Individual IgG Ab responses are represented by ΔOD. Bars indicate median value and the dotted line represents the threshold of positivity of specific Ab response to Ae. albopictus SGE (cut-off ΔOD = 0.5).

Figure 3

Evolution of individual IgG response to Ae. albopictus SGE according to initial Ab level, Reunion Island, 2010. The results of antisaliva IgG Ab level between T0 and T6 were presented for low (a), medium (b), and high (c) groups of “immune responders.” Bars indicate median value in each group and the dotted line represents the threshold of specific Ab response to Ae. albopictus SGE (ΔOD = 0.5). For all groups, the Kruskal-Wallis indicated significant difference between the different time periods: P < 0.0001, P < 0.0001, and P = 0.0012 for low, medium, and high groups, respectively. In the “low” group (a), test showed significant difference in T0 versus T2 (P = 0.0482), T0 versus T4 (P = 0.057), T0 versus T6 (P < 0.0001), T2 versus T6 (P = 0.0101), and T4 versus T6 (P = 0.0466); in “medium” group (b): T0 versus T4 (P = 0.0004), T0 versus T6 (P < 0.0001), T2 versus T6 (P < 0.0001), and T4 versus T6 (P = 0.0032); in “high” group (c): T0 versus T6 (P = 0.0004), T2 versus T6 (P = 0.0011), and T4 versus T6 (P = 0.0127).