1WHO. New influenza A ( H1N1 ) virus: global epidemiological situation[J]. Weekly epidemiological record, 2009, 84(25):249- 260.
2Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team. Emergence of a novel swine-origin influenza A (H1N1) virus in humans[J]. N Engl J Med, 2009, 360(25) :2 667-2 668.
3Webster RG, Bean WJ, Gorman OT, et al. Evolution and ecology of influenza A viruses[J]. Microbiol Rev, 1992, 56(1): 152- 179.
4Reid AH, Fanning TG, Hultin JV, et al, Origin and evolution of the 1918 "Spanish" influenza virus hemagglutinin gene[J]. Proc Natl Acad Sci USA, 1999, 96(4): 1 651-1 656.
5Matrosovich M, Tuzikov A, Bovin N, et al. Early alterations of the receptor-binding properties of H1, H2, and H3 avian influenza virus hemagglutinins after their introduction into mammals [J]. Virology, 2000, 74(18):8 502-8 512.