FIG 1 .

Genotypic assay reveals coinfection of polioviruses. (A) Schematic of assay design. HeLa cells were infected at an MOI of ~0.00001 with a mixture of equal amounts of 10 genetically marked viruses. Hypothetical genomes are depicted in a HeLa cell. Plaques were picked from the agar overlays after incubation at 37°C for 48 h. Plaque-forming viruses were amplified by infecting new cells and RT-PCR products were blotted and probed on a membrane to identify the virus(es) present. (B) Representative plaque virus samples detected by probes. The number of viruses present within each plaque was quantified. Plaques were scored as having a single parent virus (Plaque 1) or more than one parent virus (Plaque 2). (C) Distribution of the 10 marked viruses among all plaques. (D) Frequency of coinfected or non-coinfected plaque viruses versus the number of plaques per plate, with the mean ± standard error of the mean (error bar) shown (the difference was not significant [n.s.] as determined by Student’s t test).