FIGURE 4.

Patch clamp electrophysiology on recombinant SARS CoV E protein in HEK293 cells. (A) pH-dependent currents in permeant ion-minimized extracellular buffer (in mM: 90 N-Methyl-D-glucamine (NMDG), 3 CaCl₂, 90 HEPES and 90 MES). Cells in the whole-cell configuration were perfused with buffer of the indicated pH, as indicated by bars above the trace. Here, lower pH defines a higher concentration of permeant protons, which leads to increased currents. (B) Inhibition of E channel-mediated currents by rimantadine, amantadine and HMA in minimized extracellular buffer. Baseline was measured at pH 7.5, reduction in pH to pH 5.5 resulted in an E protein-mediated inward current that could be inhibited by test compounds. At the end of each measurement, pH was switched back to control (7.5). Vertical arrows indicate switch to buffer with indicated pH. Bars denote flow application of indicated concentrations of inhibitor. (C) Summary of IC₅₀ curves. Solid squares, solid line: rimantadine; solid circles, short-dashed line: amantadine; solid triangles, dash-dotted line: HMA.