Family: Botourmiaviridae

Genus: Epsilonscleroulivirus

Distinguishing features

Epsilonsclerouliviruses have a mono-segmented genome. Members of the genus have been identified in association with grapevine leaves affected by infection with the oomycete Plasmopara viticola, and are phylogenetically distinct from other botourmiaviruses.

Virion

No true virions are associated with epsilonsclerouliviruses since their genomes have no capsid protein gene.

Genome organization and replication

The Plasmopara viticola lesion associated ourmia-like virus 45 (PvaOLV45) genome is a (+) RNA molecule of 2 736 nucleotides with 53% GC content. The complete genome sequence has a 5′ non-coding region (NCR) of 56 nt and a 3′ NCR of 655 nt. The virus genome contains a single open reading frame (ORF) from positions 57 to 2 081, predicted to encode a polypeptide of 674 amino acids (75.87 kDa) that has similarity to the RNA-directed RNA polymerase (RdRP) of other botourmiaviruses (Chiapello et al., 2020). The genome of Magnaporthe oryzae botourmiavirus 7 is 2 326 nt long with a single ORF of 1 983 nt (nt positions 73–2 055) that encodes a RdRP of 660 amino acids (75.4 kDa) (Liu et al., 2020).

Biology

PvaOLV45 has been identified in grapevine leaves affected by the plant pathogenic oomycete Plasmopara viticola (Chiapello et al., 2020). Magnaporthe oryzae botourmiavirus 7 was found infecting the plant pathogenic fungus Magnaporthe oryzae (Liu et al., 2020).

Species demarcation criteria

There is only one species in the genus. Amino acid sequence identities of putative RdRP proteins between viruses belonging to distinct species of the genus Epsilonscleroulivirus should be less than 90%.