Air G M
Proc Natl Acad Sci U S A. 1981 Dec;78(12):7639-43. doi: 10.1073/pnas.78.12.7639.
Nucleotide sequences of the 3' 20% of the hemagglutinin gene of 32 influenza A virus strains from the 12 known hemagglutinin subtypes have been determined. Although the sequences of hemagglutinin genes and proteins of different subtypes differ greatly, cysteine and some other amino acid residues are totally conserved, presumably reflecting evolution of the 12 different hemagglutinins from a single gene. When viruses of one subtype, isolated over a period of time, are compared, the hemagglutinin gene and protein sequences show a slow accumulation of nucleotide changes and some amino acid changes. Since sequence data from the genes coding for the matrix and nonstructural proteins also show an accumulation of changes with time, it seems that antigenic selection (of the surface antigens) does not contribute significantly to the rate of change on influenza gene sequences. Although the rate of nucleotide change during drift is more than sufficient to account for the amino acid sequence differences observed in the 12 subtypes, there is a clear distinction, by antigenic as well as sequence analyses, between viruses of one subtype (0-9% amino acid variation) and viruses of other subtypes (20-74% amino acid variation). No virus has yet been found that is intermediate between subtypes.
已确定了来自12种已知血凝素亚型的32株甲型流感病毒株血凝素基因3'端20%的核苷酸序列。尽管不同亚型的血凝素基因和蛋白质序列差异很大，但半胱氨酸和其他一些氨基酸残基是完全保守的，推测这反映了12种不同血凝素由单一基因进化而来。当比较在一段时间内分离出的同一亚型病毒时，血凝素基因和蛋白质序列显示出核苷酸变化和一些氨基酸变化的缓慢积累。由于编码基质蛋白和非结构蛋白的基因序列数据也显示出随时间变化的积累，因此似乎（表面抗原的）抗原选择对流感基因序列的变化速率没有显著贡献。尽管在抗原漂移过程中核苷酸变化的速率足以解释12种亚型中观察到的氨基酸序列差异，但通过抗原分析和序列分析，在一种亚型的病毒（氨基酸变异0-9%）和其他亚型的病毒（氨基酸变异20-74%）之间存在明显区别。尚未发现介于各亚型之间的病毒。
