FIG. 3.

Recombination frequency of SL1 mutants. (A) The role of the DIS sequence in RNA partner selection. The recombination rates of the DIS mutant viruses with viruses containing the identical DIS sequence compared with that of two viruses harboring complementary DIS mutations. “A or B” signifies that results were obtained from two cell lines, one containing two A mutant viruses and the other containing two B mutant viruses. For example, “1A or 1B” represents results compiled from a cell line containing two 1A viruses and a cell line containing two 1B viruses. “A + B” signifies that results were obtained from two cell lines both containing an A mutant virus and a B mutant virus. For example, “1A + 1B” represents results from cell lines containing one 1A and one 1B virus. (B) The impact of dimer extension on partner selection. The recombination rate of the SL1 mutant alone or in the presence of wild-type (WT) virus was measured. Also, the double mutants containing a G- or C-loop DIS and the SL1 SM were assayed for recombination with their equivalent DIS mutant with wild-type SL1 stems. Results are depicted as the means ± standard errors (n = 7) for two independent cell lines each transfected and assayed at least three times; P-values, generated by Student's t test, indicate significant deviation from the wild-type recombination rate. The recombination rate of wild-type virus (gray columns) previously measured using the same recombination system is shown for comparison.