Abstract
In recent years, since the mutation rate of RNA virus is faster than that of DNA virus, it induces that there are many new viruses evolved from the evolution. These viruses may cause calamities at various countries and seasons, such as the avian influenza H5N1. It is an important topic to analyze the relationships among sequences, function, and evolution of RNA virus. In this thesis, we used multiple sequence alignment tools to analyze eleven protein segments of influenza A virus. Our research had two major goals, one is to find important function sites for influenza A virus, and the other one is to find species-associated sites for influenza A virus. Thus, we collected the 1918 Spanish influenza virus which was the devastating pandemic disease in the history and the pandemic disease 2009 to analyze for important function sites. We divided human, avian, and swine into three groups to find species-associated sites. Finally, we wanted to distinguish function and species-associated sites, and find the real meaning of each position in the sequence for influenza A virus.