The PB1 gene from H9N2 avian influenza virus showed high compatibility and increased mutation rate after reassorting with a human H1N1 influenza virus oleh Hongrui Cui, Guangsheng Che, Mart C. M. de Jong, Xuesong Li, Qinfang Liu, Jianmei Yang, Qiaoyang Teng, Zejun Li, Nancy Beerens