Symbiotic Interactions Between Mosquitoes and Mosquito Viruses

Abstract

Mosquitoes not only transmit human and veterinary pathogens called arboviruses (arthropod-borne viruses) but also harbor mosquito-associated insect-specific viruses (mosquito viruses) that cannot infect vertebrates. In the past, studies investigating mosquito viruses mainly focused on highly pathogenic interactions that were easier to detect than those without visible symptoms. However, the recent advances in viral metagenomics have highlighted the abundance and diversity of viruses which do not generate mass mortality in host populations. Over the last decade, this has facilitated the rapid growth of virus discovery in mosquitoes. The circumstances around the discovery of mosquito viruses greatly affected how they have been studied so far. While earlier research mainly focused on the pathogenesis caused by DNA and some double-stranded RNA viruses during larval stages, more recently discovered single-stranded RNA mosquito viruses were heavily studied for their putative interference with arboviruses in female adults. Thus, many aspects of mosquito virus interactions with their hosts and host-microbiota are still unknown. In this context, considering mosquito viruses as endosymbionts can help to identify novel research areas, in particular in relation to their long-term interactions with their hosts (e.g. relationships during all life stages, the stability of the associations at evolutionary scales, transmission routes and virulence evolution) and the possible context-dependent range of interactions (i.e. beneficial to antagonistic). Here, we review the symbiotic interactions of mosquito viruses considering different aspects of their ecology, such as transmission, host specificity, host immune system and interactions with other symbionts within the host cellular arena. Finally, we highlight related research gaps in mosquito virus research.

Aedes aegypti and Ae. albopictus microbiome/virome: new strategies for controlling arboviral transmission?

“…Unlike arboviruses, which have dual host tropism (vertebrates and arthropod vectors), ISVs replicate exclusively in insect populations and cannot replicate in vertebrate cells or infect humans [ 41 , 116 , 117 ]. Therefore, being naturally associated with arthropods, they can be considered members of viral communities of insects exclusively (viromes), and are not considered pathogens [ 104 , 117 ]. In adult insects, the highest proportion of ISVs characterized so far correspond to RNA viruses [ 104 ] without causing apparent affectation, suggesting their high adaptation and relationship with insects [ 104 ].…”

“…Therefore, being naturally associated with arthropods, they can be considered members of viral communities of insects exclusively (viromes), and are not considered pathogens [ 104 , 117 ]. In adult insects, the highest proportion of ISVs characterized so far correspond to RNA viruses [ 104 ] without causing apparent affectation, suggesting their high adaptation and relationship with insects [ 104 ].…”

“…ISVs are found at all stages of life in both male and female mosquitoes. This is associated with their efficient transmission to offspring (transovarial transmission) [ 104 , 118 ] and coexistence with their insect host over a long period [ 39 , 124 ]. In addition, there is evidence of the presence of viral RNA in the insect transcriptome and a high incidence of endogenous copies in the insect genome, suggesting a crucial role of ISV in the evolution of RNA viruses [ 126 ].…”

Antiviral RNAi Response against the Insect-Specific Agua Salud Alphavirus

“…They are considered promising for many applications, from vaccine development to arbovirus transmission control tools ( 3 ). Nevertheless, our knowledge of many important aspects of the biology of ISVs is limited, such as their interactions with the vector species that they infect ( 4 ).…”

Biological Control Against Four-Stored Product Beetles Pests by Using Cytoplasmic Polyhedrosis Virus (Cypovirus1)

“…Cypovirus1 was collected from living and dead stem and cob borer larvae and pupae and examined by electron microscopy showed that particles of Cypovirus1 are shaped icosahedral, which belong to Reoviridae. Cyoovirus1 has a single-shelled capsid [10][11][12][13]. The Cypovirus1 infects the insect larvae of stored grain pests four days after inoculation with the Cypovirus1, causing chronic larvae disease and less-lethal chemical insecticides.…”