Family: Nairoviridae

Genus: Sabavirus

Distinguishing features

South Bay virus (SBV) is the only classified sabavirus. SBV infects ixodid ticks. Notably, sabaviruses have bisegmented genomes (Tokarz et al., 2014, Shi et al., 2016, Cross et al., 2018, Tokarz et al., 2019, Qin et al., 2022).

Virion

Virions are unknown.

Nucleic acid

Sabaviruses have bisegmented negative-sense RNA genomes of 19.4 kb (small [S] segment: 5.5 kb; large [L] segment: 13.9 kb) (Tokarz et al., 2014, Shi et al., 2016, Cross et al., 2018, Tokarz et al., 2019, Qin et al., 2022). Sabavirus genomic segments are expected to assume circular forms via non-covalent binding of complementary and conserved 3′- and 5′-terminal sequences.

Proteins

Based on sequence data only, sabaviruses likely express two structural proteins: nucleoprotein (N) and large protein (L).

Genome organization and replication

The S segment encodes N and the L segment encodes L (Figure 1 Sabavirus).

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

Biology

SBV infects deer ticks (ixodid Ixodes scapularis Say, 1821) in China and the USA (Tokarz et al., 2014, Shi et al., 2016, Cross et al., 2018, Tokarz et al., 2019) and ixodid Dermacentor silvarum Olenev, 1931 ticks in China (Qin et al., 2022). Replication-competent sabavirus isolates have not yet been obtained, and hence sabavirus biology remains to be elucidated.

Species demarcation criteria

The genus currently only includes a single species.