Genetic analysis of J-virus and Beilong virus using minireplicons.

J-virus (JPV), isolated from wild mice in Australia, and Beilong virus (BeiPV), originally isolated from human mesangial cells in China and subsequently detected in rat mesangial cells, represent a new group of paramyxoviruses which have exceptionally large genomes (>19 kb) and contain more than six transcriptional units. In this study, minireplicons were employed to assess the taxonomic status of JPV and BeiPV. Our results demonstrated that, whilst the genome replication machineries of JPV and BeiPV can be interchanged, they were not functional when exchanged with that of Nipah virus. These studies indicate that JPV and BeiPV are closely related to each other and support the classification of these two viruses into a separate genus. In addition, the minireplicons were also used to demonstrate that these large-genome viruses also comply with the 'rule of six' and that over-expression of the C protein has a detrimental effect on minigenome replication.