Evolution of Influenza A and B Viruses: Conservation of Structural Features in the Hemagglutinin Genes

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 79; no. 15; pp. 4800 - 4804
• Main Authors: Krystal, Mark, Elliott, Richard M., Benz, Edmund W., Young, James F., Palese, Peter
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 01.08.1982; National Acad Sciences
• Subjects: Amino Acid Sequence; Amino acids; Base Sequence; Cercopithecine herpesvirus 1; Cloning, Molecular; Generally accepted auditing standards; Genes, Viral; Hemagglutinins, Viral - genetics; Influenza A virus; influenza B virus; Nucleotide sequences; Nucleotides; Orthomyxoviridae; Orthomyxoviridae - genetics; RNA; RNA, Viral - genetics; Sequence analysis; Viruses
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.79.15.4800

The complete nucleotide sequence of the hemagglutinin (HA) gene of a type B influenza virus (B/Lee/40) was obtained by using cloned cDNA derived from the RNA segment. The gene is 1,882 nucleotides long and can code for a protein precursor of 584 amino acids. Structural features common to type A virus HAs are also conserved in the B virus HA. These include a hydrophobic signal peptide, hydrophobic NH2and COOH termini of the HA2 subunit, and a HA1/HA2 cleavage site involving an arginine residue. The sequence of the B HA gene and its deduced amino acid sequence were compared to those of a type A influenza virus (A/PR/8/34). When these two genes were aligned, it was found that 24% of the amino acids in the HA1 subunits and 39% of the amino acids in the HA2 subunits are conserved. This degree of relatedness between type B virus and type A virus HAs (intertypic comparison) is similar to the homologies observed among certain type A virus HAs (intratypic comparison). A close evolutionary relationship is therefore suggested between the HAs of type A and type B influenza viruses.