A New Clade of Insect-Specific Flaviviruses from Australian Anopheles Mosquitoes Displays Species-Specific Host Restriction

Abstract

Flaviviruses like dengue, Zika, or West Nile virus infect millions of people each year and are transmitted to humans via infected-mosquito bites. A subset of flaviviruses can only replicate in the mosquito host, and recent studies have shown that some can interfere with pathogenic flaviviruses in mosquitoes and limit the replication and transmission of the latter. The insect-specific flaviviruses (ISFs) reported here form a new Anopheles mosquito-associated clade separate from the Aedes- and Culex-associated ISF clades. The identification of distinct clades for each mosquito genus provides new insights into the evolution and ecology of flaviviruses. One of these viruses was shown to replicate in the midgut of the mosquito host and exhibit the most specialized host restriction reported to date for ISFs. Understanding this unprecedented host restriction in ISFs could help identify the mechanisms involved in the evolution of flaviviruses and their emergence as mosquito-borne pathogens.

Dianke virus: A new mesonivirus species isolated from mosquitoes in Eastern Senegal

“…Molecular screening undertaken in the same areas resulted in detection of the same virus in 43 mosquito pools from 21 species. These results are similar to previous observations where a broad host species range in mosquitoes suggested a worldwide mesoniviruses distribution (Vasilakis et al, 2014), while Colmant et al (2017) described a speciesspecific host restriction for some insect-specific-flaviviruses.…”

Discovery of Novel Crustacean and Cephalopod Flaviviruses: Insights into the Evolution and Circulation of Flaviviruses between Marine Invertebrate and Vertebrate Hosts

“…Mono-and dinucleotide compositions have also been used in linear discriminant analyses using a training set of RNA viruses with established host ranges (vertebrate-only, invertebrate-only [cISF], vector-borne, plant, and bacterial). Using this approach, it was possible to sensitively assign Anopheles cISFs as an invertebrate-only grouping (84). Importantly, our analyses indicate that dinucleotide compositions of the marine flaviviruses discovered here associate these viruses into tentative marine invertebrate and marine vertebrate host-associated groupings.…”

Discovery of a novel iflavirus sequence in the eastern paralysis tick Ixodes holocyclus

“…Furthermore, testing for IhIV by RT-PCR in I. holocyclus samples demonstrated the presence of double-stranded RNA, an important intermediate in the replication of RNA viruses, and a relatively low prevalence in the ticks we studied suggesting that the sequence is not integrated in the host genome [34,35]. This data suggests the IhIV sequence is likely to represent the genome of a functional virus rather than an endogenous viral element in the I. holocyclus genome [34][35][36]. The presence of IhIV sequence in both blood-fed Fig.…”