FIG 5.

Growth kinetics of recombinant and parental viruses in DF-1 cells and neutralizing antibody responses against IBV. (A) DF-1 cells were infected with one of the recombinant viruses (rLa Sota/SB or rLa Sota/SBNT) or the parental virus rLa Sota at an MOI of 0.01. Viral titers in supernatant samples collected from infected cells at 12-h intervals until 72 hpi were determined by performing a TCID₅₀ assay in DF-1 cells. The titers at each time point are expressed as the mean ± standard deviation. (B) The level of antibodies against IBV was determined by virus neutralization assay. Three serum samples per group were assessed, and antibody titers are expressed as reciprocals of the log₂ dilution. Bar graph displays the mean ± standard deviation. Statistically significant differences versus the PBS group are indicated (***, P < 0.001).