Predicting The Antigenic Variant And Studying Of Antigenic Evolution Of Influenza B Virus Based On Bioinformatics

Influenza B viruses,which include both Yamagata and Victoria strains,are seasonal human influenza viruses.Because influenza viruses mutate rapidly,the antigenic variation of the virus also occurs frequently,resulting in decreased efficiency or even failure of influenza virus vaccine.Understanding the antigenic variation and evolution of influenza B virus is helpful to develop a more rapid and effective method to determine the antigenic variation of influenza B virus and to detect the antigenic variant viruses in a timely manner.In this paper,we first identified the five epitopes of influenza B virus,A-E,by integrating the gene sequence,structure and antigen data of influenza B virus through bioinformatics methods.Based on the correlation analysis of antigen variation and site/epitope change,it was found that epitopes A,B and E had the greatest influence on the antigen variation of influenza B virus.BV and BY branches differ significantly in the key sites of antigen variation.Then,based on the sequence and structural characteristics of sites and epitopes,multiple machine learning models were selected to predict and model the antigenic variation of the two branches of influenza B virus.It was found that the equivalence matrix(0/1)is the most suitable method among many scoring matrices in site-based modeling.The random forest model is the best of the four machine learning methods.BY and BV branches have different optimal prediction models,but their optimal accuracy and AUC values can reach 0.93 and 0.97 respectively.Finally,based on the prediction model of antigen variation,an antigen prediction method was established,and the antigens in two branches of influenza B virus also were predicted,simultaneously four antigens in the BV branch and five antigens in the BY branch were determined,which were roughly in line with the actual popular antigens published by the WHO.Based on the classification of antigens,We systematically studied the temporal and spatial dynamic evolution of antigens of the two branches of influenza B virus in the global and Asia,and found that most of the antigens in the two branches first appeared and prevailed in Asia,especially in East Asia and Southeast Asia,indicating these areas may be the source of the influenza B virus antigen class.In conclusion,the research of this thesis can not only deepen our understanding of the antigenic variation and evolutionary law of influenza B virus,but also has certain theoretical value.Moreover,the genetic sequence-based antigen mutation prediction model developed in this paper can help to quickly determine theoccurrence of influenza B virus.The antigenic variation and the timely detection of the antigenic variant virus provide a methodological basis for the monitoring and prevention of the virus,and have important practical application value.