FIG 4.

Role of host-pathogen fatty acid synthesis in penicillin (PEN)-induced chlamydial persistence. (A to C) Effect of the bacterial FabI inhibitor. (A) Representative images of productive and penicillin-induced persistent infection in the presence or absence of the FabI inhibitor AFN-1252 at 24 hpi. Green, immunofluorescence staining with FITC-labeled monoclonal chlamydial LOS antibodies; red, Evans blue counterstaining of host cells. Bars = 10 μm. (B) Size of chlamydial inclusions with or without AFN-1252 in productive infection at 24 hpi. (C) Sizes of chlamydial inclusions and aberrant RBs as well as numbers of aberrant RBs inside inclusions with or without AFN-1252 in penicillin-induced chlamydial persistence at 24 hpi. (D to G) Impact of host fatty acid metabolism on penicillin-induced chlamydial persistence. ACL pS⁴⁵⁵ (D) as well as AceCS1 (E) and ACSL1 (F) protein amounts were analyzed by Western blot and densitometric analyses at 24 hpi. ACL pS⁴⁵⁵ was normalized to total ACL, and AceCS1 and ACSL1 protein amounts were normalized to GAPDH. (G) Representative images of penicillin-induced persistent infection in the presence or absence of the host fatty acid synthetic inhibitor C75 at 24 hpi. Green, immunofluorescence staining with FITC-labeled monoclonal chlamydial LOS antibodies; red, Evans blue counterstaining of host cells. Bars = 10 μm. The sizes of chlamydial inclusions and aberrant RBs as well as the numbers of aberrant RBs inside inclusions were analyzed in the presence or absence of C75. Ct, C. trachomatis (n = 30 from three independent experiments [B and C]; n = 5 [D]; n = 4 [E]; n = 5 [F]; and n = 72 to 140 for the size of inclusions, n = 31 for the size of aberrant RBs, and n = 29 for aberrant RB numbers inside inclusions, from three independent experiments [G]) (means ± SEM) (*, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001; N.S., not significant [by Sidak’s multiple-comparison test {B and C} and Student’s t test {D to G}]).