GBP1 and infection: IFN-γ treated HeLa cells stably expressing hGBP1 were infected with the wild type Y. pestis strain 201 or Pa3606, alongside the various mutants of Y. pestis including ΔyspE1, Δyp_3417, Δ yspE2 and ΔyscI. The decrease of hGBP1 became apparent at one hour post-infection (hpi) in 201-infected HeLa cells, and this effect was abrogated in ΔyscI or ΔyspE2, but not in ΔyspE1 infected HeLa cells (Fig. 2e, i).