Isolation and characterization of the positive-sense replicative intermediate of a negative-strand RNA virus

Significance The negative-strand RNA viruses comprise several significant human, animal, and plant pathogens that have considerable health and economic impact globally. During infection, replication of the single-stranded negative-sense RNA genome occurs through a complementary RNA intermediate, which is believed to complex with viral proteins to form a complementary ribonucleoprotein (cRNP). The isolation of these complexes from infected cells has never been accomplished, greatly hampering our understanding of genome replication. We report a technological advance for the isolation of this elusive but essential component of the influenza A virus replication machine. Structural and functional characterization of the influenza A virus cRNP has led to the proposal of a model of genome replication that relies on a trans -activating viral RNA-dependent RNA polymerase.