Modern variations of human influenza group A viruses at the molecular level

: The authors own results on the variety of the genomic primary structures in human influenza A viruses participating in the epidemic process, including the atypical viruses. The comparative studies revealed new trends in the HA gene antigenic drift on the late stages and the PB1 gene shift. Modifications occurring in the primary structure of the influenza A viruses native genomes during laboratory treatment (adaptation to new hosts, vaccine preparation, egg passaging) have been analyzed. Sequencing of several types of "antigenic anachronisms" revealed the direct links between some of such viruses and the anthropogenic pollution of the biosphere by vaccine strains. Modifications in the HA genes of influenza A viruses during the persistent infection have also been studied.