FIG 5.

Incorporation of U12137C, C18114G, A19047U, and A20139G in nsps 10, 14, 15, and 16, respectively, within rVV M41-R generated a new rIBV, M41-K, which exhibits comparable replication kinetics in vitro. (A) Primary CK cells were inoculated with 10⁵ PFU of either rIBV M41-R-6, M41-R-12, or M41-CK. (B) Ex vivo TOCs, prepared from 2- to 3-week-old SPF chickens, were inoculated with 10⁴ PFU of either rIBV M41-R-12, M41-K-6, or M41-CK. Supernatants were harvested at 24-h intervals and the quantities of infectious progeny virus present were determined by plaque assay in CK cells. Each point represents the mean of three independent experiments with error bars representing SEM. Statistical differences were analyzed using a two-way ANOVA with Tukey analysis for multiple comparisons and are represented by * (P < 0.05) and *** (P < 0.0005). For clarity, the statistical difference highlighted in panel A denotes that the titers of both rIBV M41-K-6 and rIBV M41-K-7 are lower than that of M41-CK.