Dengue Virus-2 Infection Affects Fecundity and Elicits Specific Transcriptional Changes in the Ovaries of Aedes aegypti Mosquitoes

Abstract

Dengue fever (DF), caused by the dengue virus (DENV), is the most burdensome arboviral disease in the world, with an estimated 400 million infections each year. The Aedes aegypti mosquito is the main vector of DENV and transmits several other human pathogens, including Zika, yellow fever, and chikungunya viruses. Previous studies have shown that the pathogen infection of mosquitoes can alter reproductive fitness, revealing specific vector-pathogen interactions that are key determinants of vector competence. However, only a handful of studies have examined the effect of DENV infection in A. aegypti, showing a reduction in lifespan and fecundity over multiple blood meals. To provide a more comprehensive analysis of the impact of DENV infection on egg laying and fecundity, we assessed egg laying timing in DENV-2 blood-fed mosquitoes (infected group) compared to mock blood-fed mosquitoes (control group). We confirmed a significant decrease in fecundity during the first gonadotrophic cycle. To further investigate this phenotype and the underlying DENV-2 infection-dependent changes in gene expression, we conducted a transcriptomic analysis for differentially expressed genes in the ovaries of A. aegypti infected with DENV-2 vs. mock-infected mosquitoes. This analysis reveals several DENV-2-regulated genes; among them, we identified a group of 12 metabolic genes that we validated using reverse transcription-quantitative PCR (RT-qPCR). Interestingly, two genes found to be upregulated in DENV-infected mosquito ovaries exhibited an antiviral role for DENV-2 in an Aedes cell line. Altogether, this study offers useful insights into the virus-vector interface, highlighting the importance of gene expression changes in the mosquito’s ovary during DENV-2 infection in the first gonadotrophic cycle, triggering antiviral responses that may possibly interfere with mosquito reproduction. This information is extremely relevant for further investigation of A. aegypti’s ability to tolerate viruses since virally infected mosquitoes in nature constitute a powerful source of supporting viruses during intra-epidemic periods, causing a huge burden on the public health system.

Epizootic hemorrhagic disease virus oral infection affects midge reproduction and is vertically transmitted to offspring in the biting midge, Culicoides sonorensis (Diptera: Ceratopogonidae)

“…However, it is possible that EHDV infection alters the expression of certain genes in the midge ovaries that are important for egg development/maturation. Previously, A. aegypti mosquitoes infected with Dengue-2 virus showed reduced fecundity compared to their uninfected counterparts 31 . Subsequent transcriptomic pro ling of the ovaries of virus-infected mosquitoes showed the upregulation of several genes, which were suggested to interfere with egg production 31 .…”

“…Previously, A. aegypti mosquitoes infected with Dengue-2 virus showed reduced fecundity compared to their uninfected counterparts 31 . Subsequent transcriptomic pro ling of the ovaries of virus-infected mosquitoes showed the upregulation of several genes, which were suggested to interfere with egg production 31 . Similarly, A. aegypti infected with Chikungunya virus also showed reduced fecundity compared to uninfected mosquitoes 8 .…”

No detectable fitness cost of infection by cell-fusing agent virus in Aedes aegypti mosquitoes

“…In the case of arboviruses, several studies assessed the impact of DENV, ZIKV or CHIKV on the fecundity and fertility in Ae. aegypti mosquitoes [35,37,38,41,[56][57][58]. The effects are controversial especially for ZIKV and CHIKV, presumably because of the experimental design in each study such as the strain of mosquitoes and viruses used, the age of mosquitoes, and the number of oviposition [35,37,41,56,58].…”

Fully automated high-throughput immuno-µPlaque assay for live-attenuated tetravalent dengue vaccine development

“…In FFA, focus-forming units (FFU) are typically smaller in size as compared to viral plaques, necessitating the use of alternative staining techniques such as immunostaining to label viral antigens and quantify them discretely. This approach offers notable advantages including the use of a smaller assay plate format and a shorter assay duration, rendering it well-suited for high throughput applications and highly desirable for expeditious product development ( 20 , 21 ). Recent developments in these analytical methods include evaluating novel overlay systems ( 22 ), improving the assay throughput, and advancing plaque staining, imaging, and calculation methods ( 23 – 25 ).…”