Subfamily: Actantavirinae

Genus: Actinovirus

Distinguishing features

Bern perch virus (BRPV), Wēnlǐng minipizza batfish virus (WEMBV) and, Wēnlǐng red spikefish virus (WERSV) are the only classified actinoviruses. These viruses are associated with actinopterygian fish (Shi et al., 2018, Hierweger et al., 2021).

Virion

Virions are unknown.

Physicochemical and physical properties

Not reported.

Nucleic acid

Actinoviruses have tri-segmented, negative-sense RNA genomes of about 10.5–12.6 kb (small [S] segment: 1.0–2.4 kb; medium [M] segment: 3.4–4.0 kb; large [L] segment: 5.3–6.4 kb) (Shi et al., 2018, Costa et al., 2021, Hierweger et al., 2021, Costa et al., 2023).

Proteins

Based on sequence data only, actinoviruses likely express three structural proteins: nucleoprotein (N), glycoprotein precursor (GPC), and large protein (L). Bern perch virus may encode two additional proteins encoded in antisense orientation by the S and M segments (Shi et al., 2018, Hierweger et al., 2021).

Genome organization and replication

The S segment encodes N, the M segment encodes GPC, and the L segment encodes L (Figure 1 Actinovirus). Actinovirus genomic segments are expected to assume circular forms via non-covalent binding of complementary and conserved 3′- and 5′-terminal sequences.

Figure 1 Actinovirus. Schematic representation of actinovirus genome organization. The 5′- and 3′- ends of each segment (S, M and L) are, by analogy to other hantavirids, predicted to be complementary at their termini, likely promoting the formation of circular ribonucleoprotein complexes within the virion.

Biology

Bern perch virus (BRPV) infects European perch (percid Perca fluviatilis Linnaeus, 1758) in Germany/Switzerland (Hierweger et al., 2021), and Wēnlǐng minipizza batfish virus (WEMBV) and Wēnlǐng red spikefish virus (WERSV)  infect starry handfish (ogcocephalid Halieutaea stellata (Vahl, 1797)) and spikefish (triacanthodid Triacanthodes anomalus Temminck & Schlegel, 1850) in China, respectively (Shi et al., 2018). Unclassified, potential actinoviruses infect goblid and melanotaeniid fish in Australia (Costa et al., 2021, Costa et al., 2023). Replication-competent actinovirus isolates have not yet been obtained, and hence actinovirus biology remains to be elucidated.

Species demarcation criteria

Demarcation of species is based upon DivErsity pArtitioning by hieRarchical Clustering (DEmARC) analysis) using concatenated deduced S, M, and L segment expression product sequences (Laenen et al., 2019).

Related, unclassified viruses

Virus names and virus abbreviations are not official ICTV designations.

*Coding region sequence incomplete.