FIG. 5.

oct motif point mutants. (A) Random, multiple-point mutants of oct. For each mutant, circled nucleotides are those that were changed from the wild-type sequence. Unchanged oct nucleotides are highlighted in gray. (B) Defined point mutants of oct. Each nucleotide in oct was changed to each of the three possible alternatives. Relative plaque sizes (diameters) of mutants are depicted as the percentage of the average diameter of wild-type plaques (± standard deviation). Mutants marked with an asterisk are those for which one naturally occurring variant coronavirus oct sequence has been reported. (C) Representative plaques for the three size classes of oct single-point mutants, compared to the wild type. Plaque titrations were performed on mouse L2 cells at 37°C. Monolayers were stained with neutral red at 48 h postinfection and were photographed 18 h later.