FIG 4.

Expression of IBV multi-epitope proteins in DF-1 cells. (A) DF-1 cells were infected with rLa Sota/SBNT, rLa Sota/SB, or rLa Sota at an MOI of 0.01 for 24 h, and the expression of multi-epitope proteins SBNT and SB (at approximately 56 kDa and 24 kDa, respectively) was detected by Western blot analysis using a chicken polyclonal anti-IBV serum. Additionally, the expression of NDV HN protein (at approximately 53 kDa) was detected by Western blot analysis using a chicken polyclonal anti-NDV serum. (B) IFA of multi-epitope protein expression. DF-1 cells were infected with rLa Sota/SBNT, rLa Sota/SB, or rLa Sota at an MOI of 0.01 for 48 h, after which the cells were subjected to an IFA in which they were probed with a chicken polyclonal anti-IBV serum, incubated with an FITC-conjugated goat anti-chicken IgG antibody, and subsequently visualized under a fluorescence microscope.