The procedure for blocking infection with H319 antibodies in polarized Vero E6 cells, grown in transwell inserts, was erroneously omitted on page 1104, Section 3.13. (entitled ‘Infectivity Assays’) of [1]. It is important to note that robust blocking with H319 anti-DAF anti-bodies, as shown in Figure 5B, was measured in polarized cells, seeded on filter supports in transwell plates, as described below. [...]