Unassigned viruses in family Nanoviridae
The taxonomic status of coconut foliar decay virus (CFDV) is uncertain. CFDV was previously considered to belong to an unassigned species in the family Nanoviridae on the basis of a nucleotide sequence [GenBank M29963] that now appears to be an alphasatellite sequence. The virus is transmitted by a planthopper in contrast to the aphid-vectored nanovirids. Recently, seven distinct Rep-encoding DNAs, each of about 1.3 kb and also most closely related to alphasatellites, have been associated with coconut foliar decay disease. In addition, two distinct 1.3 kb DNAs have been detected, potentially encoding a CP of ca 24 kDa, intermediate in size between that of nanovirids (19 kDa) and geminivirids (28–34 kDa), and most closely related to that of grabloviruses (family Geminiviridae). A further 641 nt DNA may encode a movement protein. It is likely that CFDV has a tripartite genome and represents a species of a new virus family (Gronenborn et al., 2018).