The Asian tiger mosquito Aedes albopictus represents a serious threat for public health worldwide. Due to both its invasive aptitude and vector competence, it is extending to temperate regions the risk of transmission of important human arboviruses. Indeed, several cases of autochtonous transmission of dengue, chikungunya and Zika viruses have been recorded in Europe (e.g., Italy, France, Croatia, etc.) in the last fifteen years. The virus life cycle in the mosquito starts with the blood meal on an infected host. The ingested virus first invades the midgut epithelium and replicates, then disseminates through the hemolymph, and finally infects the salivary glands; from here it is transmitted to a new host with mosquito saliva during the next blood meal. Our understanding of the Ae. albopictus innate immune pathways activated during CHIKV infection is still limited, and recent evidence also highlighted that arboviral infection may affect mosquito physiology modulating, for instance, host-seeking, blood feeding and egg maturation. This project builds on a RNA-seq analysis of CHIKV-infected Ae. albopictus that we recently completed that planned to clarify the molecular interactions between the tiger mosquito and CHIKV. First, mosquito genes previously identified as modulated by CHIKV and potentially involved in key aspects of immune response, olfaction/chemoperception, feeding, egg maturation or transmission, will be screened by a reverse genetic approach based on dsRNA-mediated gene silencing. The most promising candidates will be targeted by the CRISPR-Cas9 methodology, which is currently applied to other mosquitoes but not yet established in Ae. albopictus, making its implementation in the tiger mosquito a key innovative aspect of the project. Finally, a small RNA-seq analysis of mosquito midguts soon after CHIKV invasion is expected to provide novel information on organ-specific modulation of miRNA expression and activation of antiviral siRNA and piRNA pathways.
