FIG 5.

Neuraminidase treatment infectivity assay. (A) Indirect immunofluorescent assay of Vero cells pretreated with neuraminidase (NA+) or PBS (NA−) and inoculated with recombinant virus icPC22A or icPC22A-S1Δ197. After inoculation, cells were maintained in DMEM containing 2.5% FBS. At 16 h postinoculation, cells were fixed, and the PEDV antigens were stained using mouse anti-PEDV N antibody as the primary antibody. (B) Percentage of fluorescent focus units (FFU) of sialic acid-dependent infection assay. Neuraminidase- or PBS-treated Vero cell monolayers were inoculated with equal amounts of virus (350 FFU/well).