The predicted antigenicity of the haemagglutinin of the 1918 Spanish influenza pandemic suggests an avian origin.

@article{Brownlee2001ThePA,
  title={The predicted antigenicity of the haemagglutinin of the 1918 Spanish influenza pandemic suggests an avian origin.},
  author={George G. Brownlee and Ervin Fodor},
  journal={Philosophical transactions of the Royal Society of London. Series B, Biological sciences},
  year={2001},
  volume={356 1416},
  pages={1871-6}
}
In 1982 we characterized the antigenic sites of the haemagglutinin of influenza A/PR/8/34, which is an influenza strain of the H1 subtype that was isolated from humans in 1934, by studying mutants which escaped neutralization by antibody. Four antigenic sites, namely Cb, Sa, Sb and Ca, were found to be located near the tip of the trimeric haemagglutinin spike. Based on the sequence of the haemagglutinin of the 1918 Spanish influenza, we can now specify the extent of divergence of antigenic… CONTINUE READING