Fig. 4.

In ovo characteristics of rIBVs. (A) Quantitative RT-qPCR analysis of RNA extracted from AF of ECEs collected at 12 h intervals after inoculation with IBV H52 BI, rIBV-wt, rIBV-Δ3ab, rIBV-Δ5ab, and rIBV-Δ3ab5ab was performed. Data points represent means with standard deviations of five eggs per condition, with all samples run and analyzed in triplicate using a ten-fold dilution series of IBV H52 BI as reference to determine virus quantity as EID₅₀/ml equivalents [15]; (B) Embryonic death is indicated as a percentage of all remaining animals at each time point.