Analyzing Antigenic Evolution Of Influenza A H1N1Viruses Based On The Bioinfoumatics

Continual mutations on HA protein of influenza A virus generate novel antigenic strains that cause new outbreaks. Since the ongoing antigenic changes and annual epidemics it caused, more attention have been paid to whether the future dominant antigenic sequences for influenza virus A can be tracked and predicted or not. Consequently, describing and simulating the antigenic evolution of influenza A is of critical importance for reasonable preparation before a new pandemic. In this article, we have analyzed more than1071human A/H1N1HA sequences from1918to2008, and combined the evolutionary information and the mutation features in antigenic sites under host selection pressure to build a prediction model for H1N1HA antigenic variations. Then the accuracy of this prediction model was evaluated with sequences collected from1999——2011, the result shows that except for few sites, more than50%of the real epitope types can be covered by the top100of the prediction list both within an epidemic circulation and across circulations. This prediction model provides a convenient way to get future antigenic mutants with the genomic sequence of current prevalent strain, and can help the early prediction for antigenic drift in the forthcoming season. This may be of great significance for preventing and preparation before the new H1N1epidemic. In addition, in order to demonstrate the different infection characteristics of human infected swine H1N1and human seasonal H1N1,17HA(hemagglutinin) sequences of human infected swine H1N1and21human seasonal H1N1HA sequences have been collected, with bioinformatical method, including sequence alignment, amino acid conservational analysis and3D structure comparison to illustrate the mechanism for their diverse. The results revealed the conservational level on HA epitope sites is different for these two kinds H1N1viruses, and5amino acid differences on receptor binding sites have been found, including A138S,Q192K,S193T,Q196H and A227E. These results provide information for illustrating the diverse between these two kinds of H1N1, and can be helpful in understanding the evolution of human H1N1influenza viruses.