Abstract
BACKGROUND: Mosquitoes are the main vectors of arboviruses, which infect millions of people every year. These viruses depend on host factors, such as the proprotein convertase furin, for replication. While the interactions between arboviruses and furin have been widely studied in mammals, little is known about furin homologs and their role in virus replication in mosquitoes. METHODS: We performed a comparative analysis of the sequences and predicted structures of human and other dipteran furin with their mosquito homologs. We used RT-qPCR to determine the mRNA expression of the identified furin genes. We synthesized the FITC-labeled furin inhibitor MI-1190 to analyze the uptake in C6/36 cells, larvae, and female mosquitoes. Then, we tested the toxicity of peptidomimetic furin inhibitors (MI-1148, MI-1554, and MI-1851) in vitro through cellular ATP quantification and in vivo by adding the inhibitor to the breeding water of larvae and microinjection of females. Finally, we evaluated their antiviral efficiency by quantifying the relative fluorescence generated by the viral reporter expression in cell culture and female mosquitoes. RESULTS: We identified two furin encoding genes (FLP1 and two FLP2 transcripts) and confirmed their mRNA expression in all developmental stages of Aedes albopictus and two of its cell lines. The inhibitor MI-1190 was successfully taken up in C6/36 cells, as well as by early larval stages and adult female mosquitoes. The three selected inhibitors significantly curtailed the spread of Semliki Forest virus in cell culture, thereby demonstrating their antiviral efficacy in mosquito cells. However, the antiviral effect observed in vitro did not translate in vivo, where the effect of furin inhibitor MI-1851 showed only a minor impact. CONCLUSIONS: Identifying and characterizing host factors from mosquitoes as antiviral targets is a complementary step towards developing new strategies to combat arbovirus transmission and address the ongoing global health challenge.