IFNG and infection: On the contrary, the Ctr Tn-cdu1 mutant strain showed a sensitization toward immune stimulation with interferon (IFN) γ, which became evident by a significant reduction of replication in primary cells of human fimbriae obtained from biopsies (referred as Fimb cells) reflecting the natural infection site for C. trachomatis after IFNγ treatment (Figure 7E).