pseudotuberculosis T3S. We found that INP0400 progressively inhibited

C. trachomatis L2 replication in doses from 5 to 25 μM [17]. In the present study we included another derivative of salicylidene acylhydrazide, INP0341. Dose response studies on chlamydial inclusion size showed that INP0341 was even more potent than INP0400 in inhibiting C. trachomatis L2 replication, as 10 μM INP0341 was already Anlotinib order sufficient to strongly inhibit bacterial multiplication (Fig. 1A). We also tested the effect of these two INPs on the development of another strain of Chlamydia, C. caviae GPIC. At equivalent concentrations of INPs, the effect on inclusion size was always more pronounced on C. trachomatis than A-1210477 on C. caviae inclusions, suggesting

that the latter strain is less susceptible to the drug (Fig. 1A). Treatment with 60 μM INP0341 resulted in a 99.8% reduction in the yield of infectious C. caviae EB particles. This reduction in infectivity is much greater than the decrease in inclusion size. It is consistent with the greater decrease in infectivity than inclusion size that we saw previously with INP0400 on C. trachomatis L2 [17]. In subsequent experiments we decided to use 60 μM of INPs, which fully inhibited development of C. trachomatis L2, and had a very strong effect on C. caviae multiplication. Figure 1 Effect of INPs on Chlamydia intracellular development and entry. (A) HeLa cells infected with C. trachomatis L2 (top) or C. caviae GPIC

(bottom) were grown in the presence of INP0341 for 24 h at the concentrations indicated. After fixation, IWR-1 in vitro bacteria were labelled with anti-EfTu antibody (green) and host cell nuclei were stained with Hoechst 33342 (blue). (B) HeLa cells were infected with C. trachomatis L2 or C. caviae GPIC for 2.5 h in the presence or absence of 60 μM INP0400 or INP0341 and extracellular and intracellular bacteria were differentially immunolabelled as previously described [11]. The number of extra- and intracellular bacteria in untreated Protein tyrosine phosphatase and treated cells were counted in 15 fields with an average of 75 bacteria per field. The efficiency of entry is expressed as the ratio of intracellular to total cell-associated bacteria (intracellular and extracellular). The data shown represent the average and the standard error of 30 fields from two independent experiments. In order to quantify the efficiency of Chlamydia entry in the presence of INPs, HeLa cells were infected with C. trachomatis L2 or C. caviae GPIC in the presence or absence of INP0400 or INP0341. At 2.5 h p.i. extracellular and intracellular bacteria in mock-treated (DMSO) or 60 μM INP-treated cultures were measured as previously described [11]. The efficiency of entry (intracellular/total cell associated bacteria) was quantified. INPs had no significant effect on C. trachomatis L2 and C. caviae GPIC invasion, when present during infection (Fig. 1B).