FIG 2.

Double-infected cells exhibit parallel increases in fluorescence and permeability. (A) Live-cell images and line scan analysis of WT and R2mV parasites at 25 h after invasion. Note the cell infected with multiple WT parasites produces negligible fluorescence and that the signal from two R2mV parasites is greater than from the adjacent single-infected cell. Numbered line scans showing intensity differences are show in the right panels. (B) Rainbow-scaled image of the infected cells from panel A, with color indicating mVenus fluorescence intensity. Right, zoom in images of the host membrane from these single- and double-infected cells (SI and DI). Color scale bar at right, 14 to 210 AU linear gradient. (C) Mean fluorescence intensities (MFI) ± the SEM from matched pairs of adjacent cells infected with one or two R2mV parasites, determined using whole infected cells as the defined regions of interest. Double-infected cells have increased total fluorescence intensities. *, P = 0.04 (n = 3 cell pairs). (D) Ensemble presentation of whole-cell currents in response to voltage pulses between −100 mV and +100 mV in 10-mV increments. Left and right traces are from single- and double-infected cells, respectively. The inward-rectifying currents are characteristic of PSAC activity (27). Red dashes, zero current level. (E) Mean currents (I) ± the SEM at a range of applied membrane potentials (V_m) determined from 23 single- and 10 double-infected erythrocytes (black and red symbols, respectively).