Effect of larval density and Sindbis virus infection on immune responses in Aedes aegypti
Autor(es): Kim, Chang-Hyun; Muturi, Ephantus J.
Resumo: Stressful environmental conditions during mosquito larval development may enhance susceptibility of adult mosquitoes to viral pathogens. Although anti-viral defense system in mosquitoes remains uncertain, stress-related enhancement of mosquito susceptibility to viral pathogens may be due to alteration of signaling pathways such as the Toll and immune deficiency (IMD) pathways. To test the influence of larval density and Sindbis virus (SINV) infection on mosquito Tollflind pathways, 100 or 200 Aedes aegypti larvae were reared in 2 L of live oak (Quercus virginiana) leaf infusion and the adults were fed on SINV-infected (treatments) or non-infected (controls) bovine blood. SINV infection status and expression of genes encoding three antimicrobial peptides (cecropin, defensin, diptericin), an iron-binding protein (transferrin), and four regulators of Toll/Imd pathways (caspar, cactus, RellA, Rel2) were quantified by RT-qPCR at 7 and 14 days post blood meals. Irrespective of larval density, females incubated for 14 days after an infectious blood meal had significantly higher SINV titers compared to females from low density treatments that were incubated for 7 days. For both larval densities and time intervals, there was significant down-regulation of the Tollflmd regulator genes in SINV-infected mosquitoes compared to controls. At day 7 post-infection, there was significant down-regulation of cecropin, defensin, diptericin and transferrin in SINV-infected mosquitoes at low larval density but this effect was only observed for diptericin at high larval density. These genes remained suppressed on day 14, except cecropin which was significantly up:regulated at both larval densities, and transferrin which was similar to controls at low larval density. We conclude that SW infection suppresses Tbll/rind-pathways, but high larval density enables SINV to attain maximum titers in Ae. aegypti much earlier compared to low density treatments despite the upregulation of cecropin. Published by Elsevier Ltd.
Palavras-Chave: Aedes aegypti; Larval competition; Innate immunity; Toll pathway; Imd pathway; Antimicrobial peptides
Imprenta: Journal of Insect Physiology, v. 59, n. 6, p. 604-610, 2013
Identificador do objeto digital: 10.1016/j.jinsphys.2013.03.010
Descritores: Aedes aegypti - RNA ; Aedes aegypti - Immune response ; Aedes aegypti - Immunology ; Aedes aegypti - Infectious diseases ; Aedes aegypti - Viral infections ; Aedes aegypti - Real Time PCR ; Aedes aegypti - Public health
Data de publicação: 2013
