近日，H5N1流感病毒對人類的引響與日俱增， 從禽鳥上而遭受感染的患者也越來越多。倘若禽流感病毒與其他人類流感病毒混合突變，進而演變成人類傳染人類，那可能變成一場大的災難。 Hemagglutinin (HA) 在流感病毒中，扮演著與sialic acid結合的表面醣蛋白。因此，HA蛋白與sialic acid 的結合，在病毒侵入人類呼吸道上體是非常重要的。在本文中，我們從NCBI中的Influenza Virus Resource database裡，選出了497條H5N1 HA 蛋白質序列，並使用決策樹的方式，在HA蛋白質序列中，找出有可能引響HA蛋白與sialic acid結合的胺基酸。而在最後，我們找到了4個蛋白質位子，分別是第54, 55, 241, 281的位子上，可能在感染人類上扮演重要的腳色。

Recently, the H5N1 virus has increasingly impacted to human life. It because that there are more and more people get infected. If the genome of the influenza virus recombined with the gene segments from other types of influenza viruses and caused infection through human to human, there will be a serious disaster. Hemagglutinin (HA) is the surface glycoprotein, and it will bind to sialic acid on the host cell surface receptors. So, the combination of the HA and sialic acid is important for the influenza infecting human. In this study, we select 497 sequences of the HA protein from NCBI Influenza Resource database, and use decision tree to select the key amino acid which would influence the binding of HA to sialic acid in the HA protein sequences. At the end, we have found 4 amino acid position at 54, 55, 241, and 281, those maybe important roles of the affection by H5N1 influenza virus.

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