Evolution Analysis for HA Gene of Human Influenza A H1N1 Virus (2009-2017)

摘要

This paper presents a new method to explore the evolutionary characteristics of HA gene of human influenza A (H1N1) virus from 2009 to 2017. The HA gene sequences are converted into digital vectors by the frequency of amino acids. Next, PCA cluster analysis are applied to the digital vectors. All HA gene sequences are graphically shown in a 2D or 3D space. The first two principal components account for 82% by PCA analysis. The sequences are clustered into two main parts, 2009.1-2009.2 and 2009.3-2017.1. This shows the new variants of the flu subgroup started to burst in 2009.3. Next, from the clusters, we can find that the viruses from 2009.3 and 2017.1 are divided into several small clusters on the graphical representation of HA gene sequences. However, the evolutionary distances among these small clusters are closer to each other. Results show that during 2009.3 and 2017.1 human influenza A H1N1 virus has been a gradual evolution. There was not large genetic recombination. Even so, it is necessary to monitor continuously the human influenza A (H1N1) viruses.