269 - REDUCTION OF ENZYMATIC ACTIVITY OF GLUTATHIONE S-TRANSFERASE AND MIXED FUNCTION OXIDASES IN RESPONSE TO INSECTICIDE EXPOSURE AND DENV-2 VIRAL CHALLENGE IN AEDES AEGYPTI.

Abstract: The enzymatic activity of glutathione S transferase (GST) and mixed function oxidases (MFO) regulates insecticide resistance and vector competence in Aedes aegypti. These enzymes’ activity is affected by traits such as mosquitoes’ age and feeding status. It is unknown how insecticide exposure and viral challenge could alter GST and MFO despite covariates such as age and feeding status. This work aims to determine the effects of DENV-2 viral challenge and permethrin exposure on the activity of GST and MFO regardless of age and feeding status.
We measured the activity of these enzymes in the thorax of ~30 females of Ae. aegypti (New Orleans Strain) using spectrophotometric techniques. Seven treatments were evaluated: 1) one d old, starved females, 2) 6 d old sugar-fed females, 3) blood-fed females, 4) oral DENV-2 challenged females, 5) permethrin pre-exposed and sugar-fed females, 6) permethrin pre-exposed and blood-fed females, 7) permethrin pre-exposed and oral DENV-2 challenged females. Three age groups of 6, 12, and 19 d old mosquitoes were used from treatment three to seven. A generalized linear model was used to determine the effect of permethrin exposure and viral challenge on the activity of GST and MFO.
Our results show that the activity of GST and MFO increases (p < 0.0001) proportionally with age and in the group of blood-fed individuals (p < 0.0001). However, when fixing the age and meal type, the marginal effect of permethrin exposure and viral challenge resulted in a reduction of GST and MFO activity (p < 0.001). Also, there is a statistically significant interaction between age and feeding, age and viral challenge, and feeding and viral challenge (p < 0.001). Our results show that insecticide exposure and viral challenge alter enzymatic activity in a reference strain of Ae. aegypti regardless of other biologically relevant variables such as age and meal type.