Fig. 1.

EV71 is uncoated at 30 mai and is dependent on acidification. (A) Experimental protocol for infection of RD-hSCARB2 cells with light-sensitive EV71. The red arrow indicates virus addition, the green arrow indicates the recovery of the infected cells followed by the titration of the live virus, black arrowheads indicate the start of light irradiation, gray areas indicate the periods without the light irradiation, and yellow area indicates the periods with the light irradiation. The time after the infection with light-sensitive virus is indicated. (B) Virus titer of the recovered virus. Horizontal axis indicates the onset of light irradiation after infection. The top line represents the virus titer without irradiation. Error bars represent s.d. (C) In situ hybridization for RNA genome of EV71 and immunofluorescence for the capsid proteins after infection of RD-hSCARB2 cells with EV71 in the absence or presence of NH₄Cl. The time of fixation after infection is indicated. DAPI is in blue, EV71 RNA genome is in green, whilst EV71 capsid antigens are in red. The panels on the right are enlarged 3D cross-section views of the dashed rectangles in the merged panels. Arrowheads indicate EV71 RNA+capsid double-labelled clustered vesicles. Insets are 400% enlarged panels of the arrowhead areas. Representative images are shown. Scale bars: 10 µm. (D) The numbers of visible green dots corresponding to EV71 RNA genomes per cell were shown. Number of z stack sets were three except for the 30 min NH₄Cl+ sample (two). **P<0.01. Statistical significance was determined by a two-tailed, unpaired t-test. Error bars represent s.d.