Yamada S, Suzuki Y, Suzuki T, Le MQ, Nidom CA, Sakai-Tagawa Y, Muramoto Y, Ito M, Kiso M, Horimoto T, Shinya K, Sawada T, Kiso M, Usui T, Murata T, Li Haemagglutinin mutations responsible for the binding of H5N1 influenza A viruses to human-type receptors Nature 2006