Abstract Positive selection and differential selective pressure analyses were carried out to study Haemagglutinin (HA) genes of H9N2 influenza viruses from different hosts in this paper.

• 摘要本文研究了不同寄主来源H9N2禽流感病毒血凝素基因正选择压力，以及比较了这些病毒所受选择压力的差异。