However, in the absence of infection, neither CD147 nor DPP4 abundance changes in cortical slices over time, markers of reactivity do not change from baseline, and inhibition of these receptors does not affect reactivity states (SI Appendix, Fig. 12 C, D, and F), indicating that reactive astrocytes with aberrant receptor abundance are a postinfection response. This evidence concerns the gene DPP4 and infection.