Figure 4. Kinetics of poliovirus shedding in feces.

(A) Mice were orally inoculated with 2×10⁷ PFU of poliovirus or a solution of 8% Evan's Blue dye to trace transit through the GI tract. Fresh feces were harvested from individual mice at the indicated time points, and viral titers (filled circles) or Evan's Blue Score (open squares) were determined for 2–5 mice per time point. Titer averages are indicated by the horizontal lines. Evan's Blue Score was determined by assessing the level of blue dye in fecal samples (see Materials and Methods). ND, not detected (below the detection limit). (B) Neutral red (NR) light-sensitive poliovirus was used to measure input/non-replicated vs. replicated virus in feces. Mice were orally inoculated with 2×10⁷ PFU of NR-poliovirus in the dark, and feces were harvested in the dark (right side, gray bars) or in the light (left side, white bars) at the indicated time points. Fecal virus titers were determined in HeLa cells under light or dark conditions, and NR virus titers were divided by non-NR virus titers from the same time points (in panel A) to generate normalized titer values, expressed as “% of Non-NR Virus Titer”, an indication of the viral replication level prior to shedding in feces.