FIG 1 .

Emergence of a CVB3 large-plaque variant following oral inoculation. Four- to 6-week-old male IFNAR^−/− mice were orally inoculated with 5 × 10⁷ PFU of light-sensitive, neutral-red-labeled WT CVB3 in the dark, and fecal samples were collected at 24, 48, and 72 hpi in the dark. (A) Total viral titers determined by HeLa cell plaque assays with agar overlays. (B) Percentages of replicated (noninoculum) virus in fecal samples. Flowthrough inoculum viruses are light sensitive, whereas viruses that replicated in mice are light insensitive. Aliquots of each processed fecal sample were exposed to light or dark, and replication status was determined by dividing the number of PFU/ml of light-exposed samples by the number of PFU/ml of dark-exposed samples and multiplying by 100%. Each symbol represents one mouse. (C) Representative plaque morphologies of inoculum and 48- and 72-hpi fecal samples. (D) Plaque size quantification. Each symbol represents a plaque. Large plaques are defined as the average inoculum plaque size multiplied by a factor of 10 (2.473 mm² or larger; indicated by a dashed line). For panels A and B, n = 5 to 10.