RNA editing in the phosphoprotein gene of the human parainfluenza virus type 3

RNA editing of the human parainfluenza virus type 3 (HPIV3) phosphoprotein (P) gene was found to occur for the accession of an alternate discontinuous cistron. Editing occurred within a purine-rich sequence (AAUUAAAAAAGGGGG) found at the mRNA nucleotides 791–805. This sequence resembles an HPIV3 consensus transcription termination sequence and is located at the 5′-end of the putative D protein coding sequences. Editing at an alternate site (AAUUGGAAAGGAAAGG), mRNA nucleotides 1121–1136, for accession of a conserved V cistron, which is present in a number of paramyxovirus P genes, was not found to occur in HPIV3. In contrast with many other paramyxoviruses, editing was indiscriminate with the insertion of 1–12 additional G residues not present in the gene template. RNA editing was found to occur in both in vivo (HPIV3 infected cells) and in vitro (purified nucleocapsid complexes) synthesized mRNAs. Further, the in vitro prepared mRNA was edited regardless of whether the nucleocapsid complexes were transcribed in the presence or absence of uninfected human lung carcinoma (HLC) cell lysates. These results support the notion that RNA editing appears to be exclusively a function of viral proteins.