Figure 4

IBV strain Mass41 does not utilize fAPN as an entry receptor. A & B) Primary CK cells, wild type BHK cells, BHK cells transfected with fAPN/pcDNA3.1D/TOPO, BHK cells constitutively expressing fAPN cells, or control BHK cell lines, (BHK exp.fAPN and BHK exp.pCiNeo) were separately infected with IBV_Mass41 for 12 h and labeled with monoclonal α-S1(15:88) antibody to detect viral infection in three independent experiments. Viral infectivity was determined by counting >300 cells. Error bars represent the standard deviation from the mean.