Family: Inseviridae (interim)

This is a summary page created by the ICTV Report Editors using information from associated Taxonomic Proposals and the Master Species List.

Edited by: Holly Hughes
Posted: October 2024

Summary

The family Inseviridae includes dsRNA viruses of invertebrates (Table 1 Inseviridae). The family Inseviridae was established in 2024 (Master Species List #39). The family currently is comprised of one genus, Insevirus, and 16 species.

Table 1 Inseviridae. Characteristics of members of the family Inseviridae.

Virion

Morphology

Insevirids have been shown to have an icosahedral, non-enveloped virion about 30nm in diameter (Koyama et al., 2015).

Nucleic acid

Inseviridis have a single segment of dsRNA (5.3–6.6 kb). The genome has two non-overlapping open reading frames; the downstream open reading frame may be produced through a fusion protein via a −1 ribosomal frame shift (Koyama et al., 2015, Zhang et al., 2018).

Proteins

The upstream open reading frame produces the capsid protein (about 122 kDa), and the downstream ORF after a −1 ribosomal frame shift produces the RNA-dependent RNA polymerase (RdRP, about 90 kDa) (Zhang et al., 2018). A hypothetical protein of unknown function has been identified upstream of the capsid protein in some inseviruses (Shi et al., 2019).

Genome organization and replication

Details of the replication of insevirids are unknown. The translation of the genes results in a fusion protein of the capsid and RdRP, via the presence of a pseudoknot in the intergenic region that facilitates a − ribosomal frame shift (Koyama et al., 2015) (Figure 1 Inseviridae).

Figure 1 Inseviridae. Genome organisation of Sogatella furcifera totivirus 1, a member of the family Inseviridae. Boxes indicate open reading frames as annotated on GenBank accession MG546515.

Biology

Insevirids have been identified in a wide range of invertebrates throughout the world. Inseviruses have been isolated from ants (Camponotus yamaokai) (Koyama et al., 2015), and identified by high-throughput sequencing of Aedes (Shi et al., 2019), Anopheles (Fauver et al., 2016, Colmant et al., 2017), and Culex (Wang et al., 2021) mosquitoes, white-backed planthopper (Sogtella furcifera) (Zhang et al., 2018), fruit fly (Bactrocera dorsalis) (Zhang et al., 2020), tick, Diptera, crab, and Spirurian nematodes (Shi et al., 2016).

Derivation of names

Inseviridae, Insevirus: from insect toti-like virus, referring to the host of viruses in the family and the relationship to totiviruses; the suffix viridae for family taxa or suffix -virus for genus taxa. Epithets are derived from Latinized Japanese numbers (Figure 2 Inseviridae).

Figure 2 Inseviridae. Relationships of the taxa connected to the family Inseviridae.

Species demarcation criteria

1) The host species for the virus must be assigned convincingly.

2) For viral genome sequences assembled from high-throughput sequencing reads, and not validated in full by Sanger sequencing, read numbers, RPKM values, and/or coverage depth values for the assembled sequence must be specified, or the read data must be available at NCBI such that these values can be determined.

3) Virus genome sequences that share <70% RdRP amino acid sequence identity will be considered to represent different virus species regardless of whether reported from the same or different host species.

4) Virus genome sequences that share 70% RdRP amino acid sequence identity, but are reported from different host species, are considered to represent the same virus species.