Hybridization studies of the relationship between influenza virus RNA and cellular DNA.

The possibility that an influenza RNA component was transcribed from cell DNA was examined by molecular hybridization with fowl plague virus (FPV) RNA and denatured chick cell DNA. RNA from purified preparations of FPV formed stable hybrids with chick DNA immobilized on nitrocellulose membranes. This RNA was located within virus cores produced by bromelain treatment and had properties characteristic of ribosomal RNA. To detect unique gene products in FPV-RNA and to determine the extent of homology, hybridization was carried out in solution under conditions where the denatured chick DNA was in vast excess. The kinetics of hybridization of purified FPV-RNA and chick rRNA with this DNA were compared. Two to eight percent of RNA from purified virus hybridized to DNA with a $\text{C}{}_0\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ characteristic of rRNA. Chick rRNA also competed effectively with viral RNA-DNA hybrid formation. It was concluded that influenza viruses encapsidate variable amounts of rRNA; no evidence was obtained for the existence of unique cell gene products in influenza virus RNA.