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

Abstract

Aedes (Stegomyia) aegypti, the principal global vector of dengue viruses, has differences in its susceptibility to dengue virus infection. We compared the global expression of genes in the midguts of Colombian Ae. aegypti dengue-susceptible (Cali-S) and dengue-refractory (Cali-MIB) field derived strains after ingesting either a sugarmeal, a bloodmeal, or a bloodmeal containing dengue virus serotype 2 (DENV-2). Microarray-based transcriptome analysis among treatments indicated a total of 4725 transcripts with differential expression between the two strains. Eleven genes were selected from different functional groups based on their significant up or down expression levels as well as reports in the literature suggesting they are associated with dengue virus elimination. We measured mRNA abundance of these 11 genes at 0, 8, 24, and 36 h postinfection using quantitative real time PCR (qPCR) to confirm the microarray results and assess any temporal patterns. Four genes were selected (Gram-negative binding protein-GNBP [AAEL009176], Niemann Pick Type-C2-NPC2 [AAEL015136], Keratinocyte lectin [AAEL009842], and Cathepsin-b [AAEL007585]) for knockdown experiments using RNA interference (RNAi) methodology to determine the phenotype (DENV-2 susceptible or refractory). Silencing GNBP, Cathepsin-b and Keratinocyte lectin reduced the percentage of mosquitoes with disseminated virus in the Cali-S strain to 8%, 20%, and 12% respectively compared with 96% in the controls. Silencing of NPC2 increased the percentage of mosquitos with disseminated virus infections in Cali-MIB to 66% compared with 35% in the controls. This study provides insight into genes that may contribute to the Cali-S susceptible and Cali-MIB refractory phenotypes in Ae. aegypti.

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.…”

Intracellular Interactions Between Arboviruses and Wolbachia in Aedes aegypti

“…The involvement of the host's immunity as a key player in regulating arboviral infection has been corroborated in several studies (Xi et al, 2008;Colpitts et al, 2011;Carvalho-Leandro et al, 2012;Sim et al, 2013;Anglero-Rodrıǵuez et al, 2017;Caicedo et al, 2019;Mukherjee et al, 2019;Zhao et al, 2019). Arboviruses cause Ae.…”

“…aegypti to actively respond to infection by switching immune-related genes on/off and utilizing the same genes to dictate the extent of viral susceptibility. This manifests at the transcriptomic level where high expression of leucine rich repeat (LRR)–containing proteins, Clip-domain serine proteases (CLIPBs), and Myeloid differentiation 2–related lipid recognition protein (MD-2) receptors are noted ( Figure 1 ) ( Xi et al., 2008 ; Angleró-Rodríguez et al., 2017 ; Caicedo et al., 2019 ; Zhao et al., 2019 ). LRR, CLIPBs, and MD-2 initiates Ae.…”

“…, genes such as Gram-negative binding protein – GNBP (AAEL009176) , NPC2 (AAEL015136) , Keratinocyte lectin (AAEL009842) and Cathepsin-b (AAEL007585) when inhibited in a susceptible strain of Ae. aegypti led to a significant reduction in DENV dissemination ( Caicedo et al., 2019 ). This proves the importance of these genes and their corresponding functions in DENV infection.…”

Transcriptome comparison of dengue-susceptible and -resistant field derived strains of Colombian Aedes aegypti using RNA-sequencing

“…Eighty five of the genes identified in this RNA sequencing study have been implicated in previous refractory mosquito expression studies, 10 , 12 , 13 , 19 including a microarray study on Cali-MIB and Cali-S at one time point only; 30 h after blood feeding. 20 These correlations centered on digestive genes such as trypsins and serine-endopeptidases, as well as signalling and cell entry genes such as lectins and lipoproteins. A smaller subset of immune related genes was also common, including a variety of anti-microbial peptides, CLIP (N-terminal to the chymotrypsin serine protease domain, named due to its likeness in shape to a paperclip) domains, apoptotic genes, and small RNA pathway molecules.…”