Recombination and complementation between orthomyxoviruses under conditions of abortive infection

On interaction of ts mutants of fowl plague virus (FPV) belonging to different complementation groups and human influenza A viruses under conditions of abortive infection for both partners, complementation was marked and recombinants occurred with a high frequency. The level and degree of complementation as well as the frequency of recombinants depended on the stage at which the reproduction of the human influenza A viruses involved was blocked. On simultaneous inoculation of chicks with two apathogenic ts mutants of FPV belonging to different complementation groups, pathogenic ts+ recombinants appeared. On interaction of influenza B virus with ts mutants of FPV or ultraviolet-irradiated FPV, neither complementation nor recombination was observed. There was no complementation between influenza B virus and ts mutants of FPV even at the level of the formation of virus-specific substructures.