title: Monitoring the antigenic evolution of human influenza A viruses to understand how and when viruses escape from existing immunity.
abstract: BACKGROUND
  The World Health Organization (WHO) organizes consultations in February and September of each year, spearheaded by an advisory group of experts to analyze influenza surveillance data generated by the WHO Global Influenza Surveillance and Response System (GISRS). The purpose of these consultations is to recommend the composition on influenza virus vaccines for the northern and southern hemispheres, respectively. The latest news of influenza viruses is made available to the public and updated on the WHO website. Although WHO discloses the manner in which it has made the recommendation, usually by considering epidemiological and clinical information to analyze the antigenic and genetic characteristics of seasonal influenza viruses, most individuals do not possess an understanding of antigenic drift and when it occurs.
  
  
  RESULTS
  We have constructed a web server, named Fluctrl, and implemented a pipeline whereby HA sequence data is downloaded from the Influenza Virus Resource at NCBI along with their isolation information including isolation year and location, which are parsed and managed in MySQL database. By analyzing the frequency of each amino acid residue of the HA1 domain expressed by the viruses on annual basis, users are able to obtain evolutionary dynamics of human influenza viruses corresponding with epidemics. Users are able to upload and analyze their HA1 sequences for generating evolutionary dynamics. In addition, a distribution of amino acid residues at a particular site is represented geographically to trace the location where antigenic variants are seeded.
  
  
  CONCLUSIONS
  Fluctrl is constructed for monitoring the antigenic evolution of human influenza A viruses. This tool is intended to inform the general public how and when influenza viruses evade the human body's immunity. Furthermore, leveraging the geographic information, the original locations of emerging influenza viruses can be traced. Fluctrl is freely accessible at http://sb.nhri.org.tw/fluctrl.
authors.affiliation: Division of Biostatistics and Bioinformatics, Institute of Population Health Sciences, National Health Research Institutes, Zhunan 350, Taiwan. jade@nhri.org.tw
authors.forename: Yu-Chieh
authors.initials: YC
authors.lastname: Liao
authors.forename: Hsin-Hung
authors.initials: HH
authors.lastname: Lin
authors.forename: Chieh-Hua
authors.initials: CH
authors.lastname: Lin
mesh_terms: D000595:Amino Acid Sequence; D000956:Antigens, Viral / Q000276:immunology*; D005843:Geography; D006801:Humans; D057131:Immune Evasion; D009980:Influenza A virus / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage; D008969:Molecular Sequence Data; D011159:Population Surveillance; D017386:Sequence Homology, Amino Acid
chemical_list: D000956:Antigens, Viral; D007252:Influenza Vaccines