Vector competence and innate immune responses to dengue virus infection in selected laboratory and field‐collected Stegomyia aegypti (= Aedes aegypti)

Abstract

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.

Risk of Dengue Transmission in Cocody (Abidjan, Ivory Coast)

“…Three species have been described as potential vectors of dengue viruses, i.e., A. aegypti , A. albopictus , and A. polynesiensis . In Africa, particularly in West Africa, recent dengue epidemics have been attributed to A. aegypti [11], the most active and invasive vector in the tropics [12, 13]. In Ivory Coast, several entomological prospections carried out in the city of Abidjan (Yopougon, Treichville, Marcory, Koumassi, Port-Bouet, etc.)…”

The Composition of Midgut Bacteria inAedes aegypti(Diptera: Culicidae) That Are Naturally Susceptible or Refractory to Dengue Viruses

“…These two strains originated from field-collected mosquitoes in the city of Cali, Colombia, where ~30% of field-collected mosquitoes are refractory to DENv-2 ( Ocampo and Wesson 2004 , Caicedo et al 2013 ). Subsequent studies determined that the DENv-susceptible or -refractory phenotype was determined in the midgut of these mosquitoes within 48 h of blood being ingested by the mosquitoes ( Ocampo et al 2013 , Serrato et al 2017 , Caicedo et al 2018 ). Although microbiota may exist in a variety of mosquito tissues and organs (salivary glands, ovaries, Malpighian tubules, and midgut), we examined only the gut microbiome, which serves as the first barrier to virus infection, to determine if changes in abundance or diversity of the microbiota contributed to the differential susceptibility to DENv between the Cali-MIB and Cali-S phenotypes.…”

Immune response‐related genes associated to blocking midgut dengue virus infection in Aedes aegypti strains that differ in susceptibility

“…Some genes have been implicated in contributing to Ae. aegypti VC (Osta et al, 2004;Bennett et al, 2005b;Behura et al, 2011;Ocampo et al, 2013;Serrato et al, 2017), but we still do not understand how these genes mediate pathogen-vector interactions.…”

“…We reported previously that approximately 30% of Ae. aegypti collected in the field around Cali, Colombia, are refractory to DENV-2 (Ocampo & Wesson, 2004;Serrato et al, 2017). We established colonies with different susceptibility through isofamily selection from field derived Ae.…”

“…aegypti that were selected after exposure to DENV-2 and selected the offspring from mothers with midgut infection barriers (Cali-MIB), midgut escape barriers (Cali-MEB), or no barriers (susceptible) to DENV-2 (Cali-S) . Cali-S and Cali-MIB strains maintain their phenotype toward all four serotypes of dengue, indicating that the responses are not serotype specific (Serrato et al, 2017). We performed a transcriptome study using microarrays to identify the genetic determinant to the refractoriness in the midguts of selected Cali-MIB females compared with Cali-S females in groups that had fed on sugar, blood, or infected blood (blood+DENV-2) 30 h postfeeding (hpi).…”