Pathogenicity of rCE16-HNA430T and rCE16 in 4-week-old chickens. Birds were inoculated with 105 pfu/100 μL of the indicated virus with 0.9% NaCl per bird via the intraocular and intranasal routes. A Survival curves of 4-week-old chickens. The survival curves were compared using the log-rank test. The survival data were analysed using Prism 8.0 (GraphPad Software Inc., San Diego, CA, USA). B Clinical scores of 4-week-old chickens. The mean scores per group per day are shown. C Viral loads of rCE16-HNA430T and rCE16 in chickens. Three chickens of each virus-infected group were sacrificed at 3 and 5 dpi. The detection limit was 101.48 TCID50/mL. A nonparametric (chi-square) test was applied. The values presented are the means ± SDs of the viral titres of the indicated viruses.