Larval environmental stress alters Aedes aegypti competence for Sindbis virus
Autor(es): Muturi, Ephantus J.; Kim, Chang-Hyun; Alto, Barry W.; Berenbaum, May R.; Schuler, Mary A.
Resumo: To evaluate how stress at the larval stage alters adult mosquito performance and susceptibility to viral infection. Methods We used a model system consisting of Sindbis virus (SINV) and the yellow fever mosquito Aedes aegypti. Larvae were either reared under optimal conditions (control) or exposed to one of four types of stressors; suboptimal nutrients, starvation, elevated temperature, and a low dose of the insecticide malathion and adult females were fed SINV infectious blood meal. Differential expressions of stress, immune-specific and detoxification genes was measured in fourth instar larvae (HSP70, HSP83, cecropin, defensin, transferrin and CYP6Z6) and 3-day-old females (cecropin, defensin, transferrin) to identify plausible molecular mechanisms associated with mosquito response to stress. Results There were stress-specific variations in mosquito performance (survival, development time, female size), but all stressors had a consistent effect of significantly increasing susceptibility to viral infection and dissemination relative to the controls. Three genes were up-regulated in fourth instar larvae exposed to temperature stress (cecropin, defensin and CYP6Z6) compared to single genes in suboptimal nutrient (cecropin) and malathion (transferrin) stress treatments and down-regulation of all the six genes in starvation treatments. In adult samples, transferrin was up-regulated in all but starvation treatments while defensin was up-regulated in starvation and temperature stress treatments. Conclusions Stress during larval development may cause alterations in adult mosquito phenotype and immunity that can increase their susceptibility to pathogens.Original Abstract: Objectif: Investiguer comment le stress au stade larvaire altere-t-il la performance des moustiques adultes et leur sensibilitea l'infection virale. Methodes: Nous avons utilise un systeme modele constitue du virus Sindbis (SINV) et Aedes aegypti le moustique de la fievre jaune. Les larves ont eteelevees, soit dans des conditions optimales (temoins) ou exposees a l'un des quatre types de facteurs de stress; nutriments sous-optimal, famine, temperature elevee et faible dose de l'insecticide malathion. Les femelles adultes ont ete nourries d'un repas de sang infectieux au SINV. Des expressions differentielles des genes de stress, immuno-specifiques et de desintoxication ont ete mesurees chez des larves de stade quatre (HSP70, HSP83, cecropine, defensine, transferrine et CYP6Z6) et des femelles de 3 jours (cecropine, defensine, transferrine) afin d'identifier des mecanismes moleculaires plausibles associes a la reponse des moustiques au stress. Resultats: Il y avait des variations specifiques au stress, dans la performance des moustiques (survie, temps de developpement, taille des femelles), mais tous les facteurs de stress avaient un effet consistant a augmenter de maniere significative la sensibilitea l'infection virale et la dissemination par rapport aux temoins. Trois genes ont ete up-regules chez les larves de stade quatre exposees a un stress de temperature (cecropine, defensine et CYP6Z6) par rapport a un seul gene dans le stress de nutrition sous-optimale (cecropine) et l'exposition au malathion (transferrine) et a la down-regulation de l'ensemble des six genes dans le stress de famine. Dans des echantillons d'adultes, la transferrine a ete up-regulee dans tous les stresses sauf la famine, alors que la defensine a ete up-regulee dans le stress de famine et de temperature. Conclusions: Le stress au cours du developpement larvaire peut entrainer des alterations dans le phenotype des moustiques adultes et dans l'immunite, qui peuvent accroitre leur sensibilite aux agents pathogenes.
Palavras-Chave: Vector competence; Arbovirus; Sindbis; Aedes aegypti
Imprenta: Tropical Medicine and International Health, v. 16, n. 8, p. 955-964, 2011.
Descritores: Aedes aegypti - Biochemistry ; Aedes aegypti - Immune response ; Aedes aegypti - Proteins ; Aedes aegypti - Infectious diseases ; Aedes aegypti - Viral infections ; Aedes aegypti - Molecular methods ; Aedes aegypti - Virus ; Aedes aegypti - Public health
Data de publicação: 2011
