Transcription and replication of eight RNA segments of influenza virus.

A novel quantitation system of both plus- and minus-strand RNAs for all eight genome segments of influenza virus was developed using single-strand cDNAs as the probes for hybridization, and employed for the measurement of various RNA species in influenza virus WSN-infected MDBK cells. The synthesis rate and accumulation level of plus-strand RNAs differed considerably among eight RNA segments and were under temporal control. In contrast, eight vRNA molecules of minus polarity were synthesized coordinately at similar rates. Newly synthesized plus-strand RNAs were rapidly transported into the cytoplasm, particularly during the early phase of virus infection, but vRNAs accumulated in the nuclei until the late infection phase. The present data supported the differential regulation of synthesis and the separate transport between plus- and minus-strand RNAs.