The genes associated with trans-dominance of the influenza A cold-adapted live virus vaccine.

Segment 7 (M) of the cold-adapted live influenza A virus vaccine plays a primary role in the ability of this virus to interfere with the replication of wild-type influenza A viruses. This conclusion is based on several lines of evidence. Single gene reassortant viruses derived by crossing influenza A/Ann Arbor/6/60 (H2N2) cold-adapted donor virus with an epidemic wild-type strain, A/Korea/1/82 (H3N2), were tested for their ability to interfere with wild-type parental virus in the Madin-Darby line of canine kidney cells and embryonated eggs.