Strand-specific attachment of avidin-spheres to double-stranded poliovirus RNA.

Poliovirus-specific double-stranded RNA molecules containing covalently attached protein were coupled with a biotin ester through the protein moiety. Subsequent interaction of the RNA-biotin with avidin attached to electronopaque plastic spheres led to the formation of complexes that were easily visualized in the electron microscope. Avidinspheres were associated only with one end of the RNA-biotin molecules, as seen in the electron microscope. Avidin-sphere attachment to poliovirus double-stranded RNA is strand specific, as shown by molecular hybridization of strand-specific probes to the separated strands of denatured complexes. 3HDNA complementary to polio virion RNA hybridized exclusively to the strands bearing associated spheres (+) strands whereas 125I-labeled virion RNA hybridized predominantly with strands without spheres (-)strands. This biotin-avidin labeling technique provides a means for the isolation of full-length poliovirus (-) strands and may provide a general means for isolation of double-stranded polynucleotides containing tightly attached protein.