Fig. 4.

Expression of Anx2 on the cell surface impacts the infectivity of EV71. RD cells (1 × 10⁵) were pretreated with an anti-Anx2 antibody (Ab) (10 or 20 μg/ml) or a mouse IgG1 isotype control antibody (20 μg/ml) for 1 h at 37°C before infection with EV71 (MOI, 0.2). (A) At 42 h postinfection, the virus yield was determined by a TCID₅₀ assay (means ± SE for four experiments). Asterisks indicate significant differences (P < 0.05) between anti-Anx2 antibody-pretreated and IgG1-pretreated RD cells. (B) At 42 h postinfection, the typical CPE of EV71 infection was viewed under a visible-light phase-contrast microscope, showing representative fields of the RD cells alone (Uninfected) or of EV71 infecting either untreated RD cells, anti-Anx2 antibody-pretreated cells, or control IgG1-pretreated cells. (C) Infectivity of EV71 pretreated with soluble rAnx2. EV71 was pretreated with various doses of rAnx2 at 37°C for 1 h prior to infection of RD cells (2 ×10⁵ cells). The total virus yield at 72 h postinfection was determined by a TCID₅₀ assay by using quintuplet wells for each concentration point and log₁₀ dilution of the virus. The virus titer in cells infected with EV71 but not pretreated with rAnx2 was used as a reference (100%) to calculate the percentages of reduction in the TCID₅₀ for the rAnx2-pretreated groups.