Isolation and partial characterization of a novel cytorhabdovirus from citrus trees showing foliar symptoms in Iran

Citrus ringspot is a graft-transmissible disease and at least two taxonomically distinct viral species are associated with this syndrome: Citrus psorosis virus (CPsV) and Indian citrus ringspot virus (ICRSV). Neither of these two viruses was detected, however, by serological or molecular assays, in symptomatic tissues from citrus trees in southern Iran, where the ringspot syndrome is widespread. By contrast, electron microscopy and molecular assays revealed the presence of a rhabdovirus-like virus, which was graft-transmitted to several citrus species and mechanically to herbaceous hosts. Virus particles were bacilliform and resembled rhabdovirus nucleocapsids deprived of the lipoprotein envelope. Partial sequences of the viral nucleoprotein and RNA polymerase genes showed a distant genetic relatedness with cytorhabdoviruses. This virus appears to be a novel species for which the name Iranian citrus ringspot associated virus (IrCRSaV) is suggested.