Activity of AN13762 against Toxoplasma gondii
(A) Chemical structures of benzoxaborole leads AN13762 and AN3661.
(B) Dose-response curves for inhibition of T. gondii growth in vitro in response to increasing concentration of the indicated compounds. Confluent HFF monolayer was infected with tachyzoites of T. gondii RH strain expressing the NanoLuc luciferase (RH Δku80 UPRT::NLuc-P2A-EmGFP). The T. gondii strains used in this study are listed in Table S1. Data are presented as mean ± standard deviation (SD) of at least two independent biological assays, each with 3 technical replicates. Shaded error envelopes depict 95% confidence intervals.
(C) EC50 values of each biological replicate were determined by non-linear regression analysis. EC50 data are presented as mean ± SD from at least 2 independent biological replicates, each with 3 technical replicates.
(D) HFF cells were infected with tachyzoites (RH Δku80 UPRT::NLuc-P2A-EmGFP) and incubated with 10 μM AN13762, 5 μM AN3661, or 0.1% DMSO as control. Cells were fixed 24 h post-infection and then stained with antibodies against the T. gondii inner membrane complex protein GAP45 (magenta). The cytosolic GFP is shown in green. Scale bars, 10 μm. A complete dataset can be found in Figure S1.
(E) Acute toxoplasmosis: timeline of mouse infections and treatments. Untreated mice succumbed to infection, and thus a new group of healthy CBA/JRj mice was used for the second challenge (n = 3 in each group).
(F) Survival curves of the CBA/JRj mice infected intraperitoneally (i.p.) with 103 tachyzoites of type I RH wild-type (WT) or the indicated CPSF3 mutant strains (E545K or G456S). During the first challenge, mice were treated orally with 40 mg/kg AN13762 or 200 mg/kg sulfadiazine once daily beginning 1 day post-infection (n = 6 for each condition; two independent experiments, each with three mice per experimental group). Mice surviving the primary infection were challenged a second time with the T. gondii WT strain (second challenge). A new group of naive mice was used as control (n = 3 in each group).