Family: Marnaviridae

Genus: Sogarnavirus

Distinguishing features

Members of the genus form a separate clade from other members of the family upon phylogenetic analysis of RNA-directed RNA polymerase amino acid sequences. 

Virion

Morphology

The structures of the capsid proteins and virion have been characterized for the virus Chaetoceros tenuissimus RNA virus type II (CtenRNAVII, species Sogarnavirus kimuraei) (Figure 1 Marnaviridae) (Munke et al., 2020). The VP1 protein has a unique surface loop that has not been previously observed in related invertebrate and vertebrate viruses. The characteristic VP1 “canyon” feature is obscured by another VP1 loop of the same protein and the VP2 protein has an N-terminal tail. 

Genome organization and replication

The current members have di-cistronic genomes (Figure 2 Marnaviridae). See discussion under family description. 

Biology

See discussion under family description. 

Species demarcation criteria

Species demarcation cut-offs are based on pairwise comparisons of the RdRP and capsid amino acid sequences. The cut-offs are 90% identity for the RdRP and 75% identity for the capsid. The phylogenetic relationship of classified virus isolates and numerous unclassified viruses is shown in Figrue 1 Sogarnavirus. 

Figure 1 Sogarnavirus.  Maximum likelihood tree of sogarnavirus RdRP amino sequences. The tree was produced using the JTT model with a gamma distribution of frequencies and invariant sites. Bootstrap values are shown where they were over 70%. Tips are labelled with filled circles for members of species; open circles represent unclassified viruses. Heterosigma akashiwo RNA virus (AY337486) was used as an outgroup. This phylogenetic tree and corresponding sequence alignment are available to download from the Resources page.

Member species

The Member Species table enumerating important virus exemplars classified under each species of the genus is provided at the bottom of the page.

Related, unclassified viruses

Virus names and virus abbreviations are not official ICTV designations.