CO-PACKAGING OF NON-VECTOR RNAS GENERATES REPLICATION-DEFECTIVE RETROVIRAL VECTOR PARTICLES - A NOVEL-APPROACH FOR BLOCKING RETROVIRUS REPLICATION

A Moloney murine leukemia virus (MoMuLV)-derived packaging retroviral vector, pUCMoTN-PR3, was previously developed in which the packaging ( psi) signal was cloned within the 5'-long terminal repeat (LTR) U3-r a nd U5 sequences, The MoTN-PR3 vector particles released from a transfe cted packaging cell line contain RNAs with r-psi-U5 sequences at the 5 '-end and U3-r sequences at the 3'-end, Upon infection, these vector p articles can efficiently transduce the neomycin phosphotransferase (ne o) gene to the target cells, The structure of the proviral DNA synthes ized in these cells was shown to contain modified 5'- and 3'-LTRs with U3-r-psi-U5 sequences, indicating that this vector can undergo revers e transcription and integration, Analysis of psi signal-containing RNA s revealed that in addition to vector RNA transcribed from the MoMuLV 5'-LTR promoter, readthrough neo RNA transcribed from the internal her pes simplex virus (HSV) thymidine kinase (tk) promoter and cellular RN As transcribed from the MoMuLV 3'-LTR promoter are produced, Of these, the downstream cellular RNAs are also packaged within the vector part icles, These vector particles containing the vector and non-vector RNA s carrying the MoMuLV psi signal are non-infectious. It is proposed th at intracellular expression of packageable non-viral RNAs may represen t an effective strategy for inhibiting animal and plant virus replicat ion.