Optimization of VACV A4L-Venus sorting conditions. (A) Histogram of cells sorted by Venus expression levels. Uninfected cells (green line), VACV A4L-Venus MOI 5 infected cells (blue line), and VACV A4L-Venus MOI 0.05 infected cells (red line) demonstrate ability to sort by level of Venus expression. (B) Percentage of cells collected in the low-Venus gate, set by the uninfected cell population, and percentage of cells in the high-Venus gate, set by the VACV A4L-Venus MOI 5 infected cells, for each of the three samples.