An Explanation of the Interpandemic Antigenic Mutability of Influenza Viruses

The unique and extreme antigenic changes of human influenza A viruses associated with pandemics have been postulated to originate in animal reservoirs, perhaps through genetic recombination of human and animal viruses. The lesser interpandemic antigenic mutations of the virus are also unique and unexplained. It is proposed that autorecombination within the infected host can salvage the mutations occurring in noninfective virus particles for ultimate incorporation into infective virions, thus creating an extended mutational pool. Selection of antigenic mutants would then be favored within individuals possessing antibodies specific for the original infecting virus.