Influenza A (H1N1) virus is a severe threat worldwide. It is important to gain abetter understanding of the mechanism of the infection. In the paper, we established a computational framework to investigate the crosstalk between the virus and the host, by finding Out the proteins that the virus is attacking. The targeted proteins were predicted by taking human proteins laid on the same GO functions or processes as the virus proteins. One hundred and one core proteins were identified. The results provide some knowledge of the possible biological processes and molecular interactions caused by the viral infection, including the host responses. (C) 2009 Published by Elsevier Inc.