INFLUENZA B-VIRUS GENOME - SEQUENCES AND STRUCTURAL ORGANIZATION OF RNA SEGMENT-8 AND THE MESSENGER-RNAS CODING FOR THE NS1 AND NS2 PROTEINS

Double-stranded DNA derived from influenza B virus genome RNA segment 8, which codes for the NS1 and NS2-proteins, was constructed by hybridization of full-length c[complementary]DNA copies of RNA segment 8 and of the NS1 mRNA. This DNA was cloned in plasmid pBR322 and sequenced. The NS1 mRNA (.apprx. 1080 viral nucleotides) contains nonviral nucleotides at its 5'' end and is capable of coding for a protein of 281 amino acids. Sequencing of the NS2 mRNA showed that it contains an interrupted sequence of 655 nucleotides and is most likely synthesized by a splicing mechanism. The first .apprx. 75 virus-specific nucleotides at the 5'' end of the NS2 mRNA are the same as are found at the 5''-end of the NS1 mRNA. This region contains the initiation codon for protein synthesis and coding information for 10 amino acids common to the 2 proteins. The .apprx. 350-nucleotide body region of the NS2 mRNA can be translated in the +1 reading frame and the sequence indicates that the NS1 and NS2 protein-coding regions overlap by 52 amino acids translated from different reading frames. Thus, between the influenza A and B viruses, the organization of the NS1 and NS2 mRNA and the sizes of the NS2 mRNA and protein are conserved despite the larger size of the influenza B virus RNA segment, NS1 mRNA and NS1 protein.