Characterization of Prototype Foamy Virus Infectivity in Transportin 3 Knockdown Human 293t Cell Line

The foamy viruses are currently considered essential for development as vectors for gene delivery. Previous studies demonstrated that prototype foamy virus (PFV) can infect and replicate prevalently in a variety of cell types for its exclusive replication strategy. However, the virus-host interaction, especially PFV-transportin3 (TNPO3), is still poorly understood. In our investigation of the role of TNPO3 in PFV infection, we found lower virus production in TNPO3 knockdown (KD) cells compared with wild-type 293T cells. PCR analysis revealed that viral DNAs were mostly altered to circular forms: both 1-long terminal repeat (1-LTR) and 2-LTR in TNPO3 KD cells. We therefore suggest that TNPO3 is required for successful PFV replication, at least at/after the nuclear entry step of viral DNA. These findings highlight the obscure mysteries of PFV-host interaction and the requirement of TNPO3 for productive infection of PFV in 293T cells.