Title : Human IgG responses to Anopheles gambiae immunogenic salivary proteins in urban and rural populations of Burkina Faso: biomarkers of exposure to malaria vector bites
Abstract:
Malaria control programs would be greatly facilitated by developing new tools for rapidly assessing malaria transmission intensity. In malaria-endemic areas like Burkina Faso, human populations are frequently exposed to immunomodulatory salivary components injected during mosquito blood feeding. Numerous studies have examined parasite immunity. However, there are few data available on vector immunity as a means of assessing malaria transmission in sub-Saharan Africa. The present study aims to compare the IgG response specific to salivary gland extract (SGE) of An. gambiae in populations living in urban areas and those living in rural areas in Burkina Faso.
A cross-sectional descriptive study was carried out in two sites, Ouagadougou and Sapouy, where blood samples (n=676) from children (0–15 years) and adults were collected. After An. gambiae salivary proteins isolation (entomological data), antibody (IgG) response to those salivary glands extracts were evaluated by ELISA, representing a proxy of An. exposure. The difference in the antibody concentrations between groups was tested using the parametric tests (Student test and ANOVA) and the nonparametric Mann-Whitney U (Wilcoxon rank-sum) test. All differences were considered significant with a p < 0.05.
The study population consisted of 63.0% males and 37.0% females (average age = 31.2 ± 17.8 years). The IgG antibodies against An. gambiae salivary protein were present in all participants of the study. Urban participants demonstrated greater exposure to An. gambiae bites compared to rural ones (p < 0.0001). The mean IgG level was higher in secondary school children compared to primary school children (p < 0.0001). Organic cotton farmers were highly exposed to An. gambiae bites compared to conventional cotton farmers (p = 0.0027).
The search for IgG specific to mosquito salivary gland extracts as immunological biomarkers in populations in Burkina Faso allowed us to show that the level of exposure to mosquito bites is strongly influenced by the living environment and the use of insecticides in agriculture.
