AIF1 and escherichia coli infection: In addition, while Iba-1 immunoreactivity remained higher in E. coli-infected pups after 7 days of infection (Fig. 2g), levels of GFAP (Fig. 2h) in infected pups were similar to control levels at this later timepoint, thus indicating that hippocampal astrocytes undergo a transient activation following E. coli infection.