Fig. 4

Bacterial colonization is impaired in putative aminotransferase gene-deficient pneumococci and is partially restored upon IAV coinfection. Mice (n = 4−12 in each group) were intranasally infected with or without IAV, followed 4 days later by intranasal inoculation with 1 × 10⁶ CFU of S. pneumoniae putative aminotransferase gene deletion mutant (S3-ΔPA) or wild-type strain (S3-WT). After one or two days post bacterial infection, the mice were sacrificed and the bacterial burden in the mouse lung was assessed via plate counting. Each symbol represents the bacterial burdens value for an individual animal (*, p < 0.01, Mann–Whitney U test compare to mock-treated). CFU colony forming unit, DPI days post-bacterial infection, Mock without pre-challenged with IAV