Inhibition of autophagy reduces DENV infection and virus titer after DENV infection with or without enhancing antibody.

<p>(A) KU812 cells were transfected with strawberry or strawberry-Atg4B^C74A plasmids. After transfection and incubation for 48 h, strawberry- and strawberry-Atg4B^C74A-expressing KU812 cells were infected with DENV or DENV with sub-neutralizing dengue patient sera. After 24 h post-infection, cells were fixed, permeabilized, stained with anti-E (green), and observed by confocal microscopy. The arrowheads indicate the strawberry- and strawberry-Atg4B^C74A-expressing cells (red). The arrows (merge) indicate the cells which possess both green and red fluorescence. The visible images of total cells are shown in the right panels. The imaging data were repeated three times and one set of representative results is shown. (B) The number of E-positive cells was counted from 200 red cells from Fig. 5A. The percentage of E-positive cells from red cells was then quantified. The means ± SD of three independent experiments are shown. (C) KU812 cells were transfected with strawberry or strawberry-Atg4B^C74A plasmids. After transfection and incubation for 48 h, strawberry- and strawberry-Atg4B^C74A-expressing KU812 cells were infected with DENV or DENV with sub-neutralizing dengue patient sera. After 24 h post-infection, cells were fixed, permeabilized, stained with anti-NS4B, and followed by Alexa647-conjugated secondary antibody. The percentage of NS4B-positive cells in red cells was then determined by flow cytometry. The means ± SD of three independent experiments are shown. (D and E) After 24 h post-infection, the culture supernatant (D) and the mixture of cell and culture supernatant (E) were collected to detect the viral titers by plaque assay. The means ± SD of three independent experiments are shown. *<i>P</i><0.05, **<i>P</i><0.01, ***<i>P</i><0.005.