A novel rhabdovirus persistently infects lepidopteran cell lines

A novel rhabdovirus was identified in BmN-4 (BmN) cells derived from Bombyx mori and Sf9 cells derived from Spodoptera frugiperda. Genome sequence homology revealed that this novel virus is distinct from the previously reported Spodoptera frugiperda rhabdovirus (SfRV). Given the high similarity of the large protein sequence of this virus to that of the Taarstrup virus, we named it Bombyx mori taarstrup virus (BmTV). When BmTV-negative B. mori-derived cultured cells were inoculated with BmTV, an increase in virus RNA was observed, but no impact on host cell proliferation occurred, suggesting that BmTV exhibits latent infection in insect cells. On the other hand, oral and hemocoel inoculation in B. mori larvae did not cause significant increase in BmTV replication. After subcutaneous inoculation, no difference in adult metamorphosis was observed between BmTV- and mock-inoculated larvae. No virus RNA was detected in eggs laid by adults that had been inoculated with BmTV at larval stage. These findings demonstrate that BmTV is a novel rhabdovirus that persistently infects several lepidopteran cultured cells.