RESUMEN
Control of dengue virus (DenV) transmission, primarily based on strategies to reduce populations of the principle vector Stegomya aegypti (= Aedes aegypti) (Diptera: Culicidae), is difficult to sustain over time. Other potential strategies aim to manipulate characteristics such as vector competence (VC), the innate capacity of the vector to transmit the virus. Previous studies have identified genetic factors, including differential expression of apoptosis-related genes, associated with the refractory and susceptible phenotypes in selected strains of S. aegypti from Cali, Colombia. The present study was designed to evaluate the variability of VC in selected strains against different DenV serotypes and to determine whether field-collected mosquitoes respond similarly to selected laboratory strains in terms of enhanced or reduced expression of apoptosis-related genes. Vector competence differed between strains, but did not differ in response to different DenV serotypes. Differences in VC were observed among mosquitoes collected from different localities in Cali. The overexpression of the pro-apoptosis genes, caspase 16 and Aedronc, was conserved in field-collected refractory mosquitoes and the selected laboratory refractory strain. The results suggest that the apoptosis response is conserved among all refractory mosquitoes to inhibit the development of all DenV serotypes.
Asunto(s)
Aedes/fisiología , Aedes/virología , Dengue/transmisión , Inmunidad Innata , Insectos Vectores/fisiología , Aedes/genética , Aedes/inmunología , Animales , Virus del Dengue/fisiología , Femenino , Insectos Vectores/genética , Insectos Vectores/inmunología , Insectos Vectores/virologíaRESUMEN
An antimicrobial peptide belonging to the defensin family of small cationic peptides associated with innate immunity in insects was isolated from the hemolymph of Rhodnius prolixus, a vector of Chagas disease. This peptide, designated R. prolixus defensin A, was purified and sequenced. The active peptide contains 43 residues and aligns well with other insect defensins. However the pre-pro region of the sequence has little shared identity with other insect defensins. We have identified 3 isoforms of R. prolixus defensin from cDNA clones obtained from RNA isolated from the whole bodies of immune activated insects. Northern analysis and Real-Time Quantitative PCR indicate that there is a very low baseline transcription of this peptide in naïve insects, and that transcription increases significantly in the fat body of immune activated insects. In addition there is a delayed induction of transcription of this peptide in the intestine 24 h post activation suggesting that the midgut/intestine of this species is active in the immune response against pathogens.