Expression of IBV S protein in DF-1 cells infected with the rNDV-vectored IBV vaccine candidates. A Western blot analysis of IBV S protein. DF-1 cell lysates were analyzed 48 hpi by Western blot analysis using polyclonal IBV antisera (top panel). Analysis of incorporation of IBV S protein into purified rNDV virions from infective allantoic fluid by Western blot analysis using polyclonal IBV antisera (bottom panel). M, Marker; 1, rLaSota/wt.S; 2, rLaSota/S(Y1145A) + Fct12; 3, rLaSota/SΔct + Fct12; 4, rLaSota; 5, mock-infected. B Immunofluorescence analysis of the intracellular and surface expression of IBV S protein in DF-1 cells infected with the rNDV-vectored IBV vaccine candidates. The cells were probed with polyclonal IBV antisera followed by detection with FITC-conjugated goat anti-chicken IgG antibodies (green) and DAPI (blue) and subsequently visualized using a confocal Zeiss LSM 510 fluorescence microscope.