FIG. 4.

Four types of theoretical recombinants that may arise during homologous crossovers between two coinfecting RNA molecules carrying two different marker mutations. (a and b) Crossovers between molecules of two markers at different locations; the progeny recombinants carry either no marker mutations (Mut1/2) or two marker mutations (Mut2/1). (c and d) Crossover between two RNAs carrying the same marker mutation, leading to their reconstruction. The grey line represents RNA molecules, and the circles represent marker mutations.