Diaphorina citri densovirus is a persistently infecting virus with a hybrid genome organization and unique transcription strategy

Abstract

Diaphorina citri densovirus (DcDV) is an ambisense densovirus with a 5071 nt genome. Phylogenetic analysis places DcDV in an intermediate position between those in the <i>Ambidensovirus</i> and <i>Iteradensovirus</i> genera, a finding that is consistent with the observation that DcDV possesses an <i>Iteradensoviris</i>-like non-structural (NS) protein-gene cassette, but a capsid-protein (VP) gene cassette resembling those of other ambisense densoviruses. DcDV is maternally transmitted to 100 % of the progeny of infected female <i>Diaphorina citri</i>, and the progeny of infected females carry DcDV as a persistent infection without outward phenotypic effects. We were unable to infect naïve individuals by oral inoculation, however low levels of transient viral replication are detected following intrathoracic injection of DcDV virions into uninfected <i>D. citri</i> insects. Transcript mapping indicates that DcDV produces one transcript each from the NS and VP gene cassettes and that these transcripts are polyadenylated at internal sites to produce a ~2.2 kb transcript encoding the NS proteins and a ~2.4 kb transcript encoding the VP proteins. Additionally, we found that transcriptional readthrough leads to the production of longer non-canonical transcripts from both genomic strands.