Separation of the plus and minus strands of cytoplasmic polyhedrosis virus and human reovirus double-stranded genome RNAs by gel electrophoresis.

The complementary strands of most of the genome double-stranded RNA segments of insect cytoplasmic polyhedrosis virus (CPV) and human reovirus are separated for the first time by agarose gel electrophoresis in in the presence of 7 M urea. CPV (+) strands and most reovirus (-) strands migrate faster than the corresponding strands of opposite polarity. Glyoxal treatment, which modifies guanine residues and prevents G-C basepairing, results in a loss of strand resolution and concomitantly a significant decrease in electrophoretic mobilities. Reovirus mRNAs synthesized in vitro with ITP substituted for GTP show similar decreased electrophoretic mobilities as the glyoxalated mRNAs. These results clearly indicate that the basis for (+) and (-) strand resolution is the presence of secondary structure formed mainly by G-C(U) base-pairs that are maintained during gel electrophoresis in the presence of 7 M urea. When the plus and minus strands of CPV genomes were separated and compared for protein synthesizing activity, it was found that only the plus strands were able to form stable 80S ribosome-RNA initiation complexes in wheat germ cell-free extracts.