Cloning of influenza cDNA into M13: the sequence of the RNA segment encoding the A/PR/8/34 matrix protein

A strategy has been developed for sequencing the single-stranded RNA genes of influenza virus. Restriction fragments derived from double-stranded cDNA copies of total influenza RNA were cloned into the bacteriophage M13mp2 and sequenced by the dideoxy technique. Sequences were extended and overlapped by using the virion RNA as template and priming with small restriction fragments. In the course of this strategy, the nucleotide sequence of segment 7 (1027 nucleotides) was completed and provides the primary structure of the matrix protein (27, 861 daltons). In addition, there is a second long reading frame which partly overlaps the reading frame of the matrix protein.