AIF1 and infection: As shown in Figures 2(a) and 2(c), the hippocampal formation of noninfected deficient as well as WT mice showed only very few GFAP or Iba-1 positive cells whereas the infection with Streptococcus pneumoniae resulted, as expected, in a strong increase in the number of GFAP or Iba-1-immunoreactive cells in WT mice.