Nucleotide sequence and in vitro expression of rubella virus 24S subgenomic messenger RNA encoding the structural proteins E1, E2 and C.

The complete nucleotide sequence of the 24S subgenomic mRNA of wild-type M33 strain rubella virus has been determined. This RNA is 3,383 nucleotides in length excluding the 3'-terminal poly(A) tract. After the three multiple in-phase termination codons clustered in the 5' terminus of this RNA, there are 81 nucleotides of nontranslated nucleic acid followed by a reading frame of 2,978 nucleotides that encodes the 110 kD precursor of the structural proteins. The 3'-untranslated region is 263 nucleotides. The 110 kD polyprotein is processed to produce nucleocapsid C, the glycoproteins E2 and E1 in that order. Sites of post-translational cleavage to produce E2 and E1 were located using available N-terminal amino acid sequences. RNAs synthesized by transcription in vitro are effective messengers in the rabbit reticulocyte cell-free translation system. Post-translational processing of the structural proteins was observed in the cell-free system supplemented with microsomes from dog pancreas.