Since only one genus is currently recognized, the genus description corresponds to the family description.
Members of the genus Megabirnavirus infect filamentous fungi. The exemplar member of the type species of the genus has bisegmented dsRNA genome of 7.2–8.9 kbp including long UTRs (1.6–1.7 kb) upstream of the 5′-proximal ORF on the coding strands. The genome is encapsidated into non-enveloped spherical particles of approximately 50 nm in diameter. The RNA-directed RNA polymerase (RdRP) is translated from bicistronic transcripts of dsRNA1 as a CP-RdRP fusion product via programmed −1 ribosomal frameshifting.
Species demarcation criteria
Not yet defined since only a single species has been assigned.
Related, unclassified viruses
See discussion under family description.