The diversity of influenza A arises from variations in the two proteins on its surface, called hemagglutinin (abbreviated H or HA) and neuraminidase (N or NA).

• 甲型流感病毒的多样性来源于其表面两种蛋白的变化，这两种蛋白就是血凝素（简称A或HA）和神经氨酸酶（简称N或NA）。