Fig. 4

In vivo fitness and virulence of a χ7122 pgl integrant following intra-air sac or oral challenge of chickens. a Experimental design of intra-air sac challenge model; b Colonisation levels of χ7122 wt and χ7122 pgl in chicken lungs, liver and spleen were assessed 8 h post challenge; c Experimental design of oral challenge model; d Colonisation levels of mixed cultures of χ7122 wt and χ7122 pgl observed 2 days and 7 days post-challenge with either 10⁵ or 10⁷ challenge doses in the caecum. Colonisation levels are expressed as log₁₀ CFU/g; e Competitive indices of χ7122 wt and χ7122 pgl in the caecum observed 2 and 7 days post-challenge with either 10⁵ or 10⁷ challenge doses. Statistically significant differences are highlighted with * indicating p < 0.05 (Mann–Whitney U test). Data are presented as median values with 95% confidence intervals