FIG. 3.

Growth kinetics of rNDV/SIVgag in embryonated chicken eggs. Embryonated eggs were inoculated with 100 PFU of rNDV/B1 or rNDV/SIVgag viruses and allantoic fluids were harvested at different time points (24, 48, and 72 h postinoculation). Viral titers at these time points were determined as TCID₅₀ by using an immunofluorescence assay. Briefly, 96-well plates containing 70 to 80% confluent Vero cells were infected with serial 10-fold dilutions of allantoic fluids (4 wells per dilution). Cells were incubated for 2 days and then fixed with 2.5% formaldehyde containing 0.1% Triton X-100. Viral proteins were visualized by using an anti-NDV rabbit serum followed by fluorescein isothiocyanate-conjugated anti-rabbit IgG.