An expansion of cytochrome P450 genes in triatomines is associated with pyrethroid resistance

PEDRINI, NICOLÁS; CALDERÓN-FERNÁNDEZ, G. M; J. A. SALAMANCA; DULBECCO, ANDREA B.; MORICONI, DÉBORA E; KUMAR, S; JUÁREZ, M PATRICIA

Congreso; SAIB 2016; 2016

Residual spray with chemical insecticides has been a successful control strategy against Chagas disease vectors. However, after about 30 years of pyrethroid application, resistant foci of Triatoma infestans are increasingly being documented both in Argentina and Bolivia. Among genes involved in detoxification processes, cytochrome P450 monooxygenases (CYP) are often associated with relevant roles in metabolic resistance. We have documented an expansion of CYP genes in Rhodnius prolixus genome, specifically into subfamilies CYP4EM (6 genes) and CYP3093A (10 genes). One member of each subfamily-specific expansion were highly expressed (18- and 91-fold induction, respectively) in the integument of deltamethrin-resistant fifth-instar T. infestans nymphs compared with deltamethrin-susceptible specimen. After modeling the molecular docking of deltamethrin to the predicted active sites, the pyrethroid binding was energetically favorable for both CYP families in T. infestans but not in R. prolixus. These results suggest that a combination of several mechanisms, i.e. genome-wide gene expansion, induction of gene expression and modification of binding affinity to the active site, might be responsible for the high levels of deltamethrin resistance detected in T. infestans. Ongoing studies of gene silencing will help to understand the mechanisms involved in such resistance.