Arbovirus interaction with mosquito innate immune responses

It is known for several arthropods that they have different innate immune responses against viruses, some working globally antiviral and others been specific for a certain virus. The RNA interference (RNAi) pathway is able to restrict virus infection in a wide range of arthropods including mosquitoes and ticks. RNAi can be divided in several pathway depended on the small RNAs produced: small interfering RNA (siRNA) either exogenous (known as antiviral response) or endogenous, microRNA (miRNA) and PIWI-interacting RNA (piRNA). These molecules have divergent roles in different cellular processes and virus-vector interactions.

‌Recently, it has been shown that antiviral responses implicating RNAi pathways are also present in mosquito cells, which lack the well-known antiviral RNAi response.

The piRNA-mediated response has been recently suggested as an additional antiviral pathway in mosquitoes following the discovery of arboviral specific piRNA-like molecules in infected aedine mosquitoes and their derived cell lines. However, little is known about the induction, mechanism and importance of the piRNA pathway on arboviral and mosquito-specific viral infection in aedine mosquitoes.

Presently, research in my group focuses mainly on mosquito-borne (arbo)viruses (such as Zika virus, chikungunya virus and dengue virus) and the role of poorly characterized small RNA pathways (such as the piRNA pathway) in the antiviral response in mosquitoes. The aim is to determine the influence of these pathways on successful arbovirus transmission from the mosquito vector to a mammalian host (vector competence).

Mosquito-specific viruses

In addition to arboviruses that infect and replicate in both arthropods and vertebrates, there is a class of arthropod-specific viruses that replicate only in arthropods. In recent years, the list of these ‘mosquito specific viruses’ (MSVs) has been growing, encompassing viruses from different families (Flaviviridae, Bunyaviridae, Togaviridae) as well as some that are unclassified. Studies show that many mosquitoes are naturally infected with at least one MSV, but it is not known if some MSVs are an ancestral form of arboviruses. Moreover, recent evidence suggests that co- or sequential- infections of MSVs and arboviruses in mosquitoes can change the infection outcome of arboviruses and the vector competence of mosquitoes, possibly through their interaction with the mosquito innate immune response.

Assessing the possibility of MSVs to become arboviruses, and effects of MSV infection on arbovirus transmission, present an additional research interest.