THE SENDAI VIRUS P-GENE EXPRESSES BOTH AN ESSENTIAL PROTEIN AND AN INHIBITOR OF RNA-SYNTHESIS BY SHUFFLING MODULES VIA MESSENGER-RNA EDITING

The P gene of Sendai virus expresses as many as eight proteins, two of which (V and W) are expressed only from edited mRNAs; only the P protein is known to be involved in RNA synthesis. To examine the functions of the other P gene proteins, we developed an in vivo system in which genome replication is driven by plasmid generated viral proteins. We found that P was essential for this process, whereas V and W were not only non-essential they were inhibitory. By using various P gene deletions and varying the amounts of plasmids transfected, we provide evidence that P is a modular protein. The N-terminal domain (shared with V and W) hinds the L or polymerase protein, whereas the C-terminal domain binds the nucleoprotein NP. A model of paramyxovirus RNA synthesis is presented, and the implications of negative regulation during persistent infection are discussed.