Figure 1

TEM observations of native and acid pH- or proteolytic enzyme-treated GII.4 VLP capsids after negative staining. A. GII.4 VLPs after exposure to pH 7.4, 1.3, and 2.0. B. GII.4 VLPs after exposure to 0 and 1,500 units/mL pepsin at pH 2.0. C. GII.4 VLPs after exposure to trypsin (0, 0.1, and 100 mg/mL) at pH 8.0. D. GII.4 VLPs after exposure to chymotrypsin (0, 0.1, and 100 mg/mL) at pH 8.0. The scale bar (solid line, bottom left corner) is 0.2 µm and 100 nm for X 15,000 and X 27,500 magnifications, respectively.