Fig. 1: H107e displays enhanced protein expression and synergizes with BCG co-administration.

a Antigen design of the H107e construct. H107e was modified from H107 through deletion of a proline-rich fraction of 220 AA in the Espl/Rv3876 antigen (Δ75–294). b Expression of the H107 and H107e constructs (OD adjusted cultures) as shown by SDS-PAGE (upper) and Western Blot (lower) at 0, 1-, and 3-h post-induction. Protein purity was estimated to be above 95% based on SDS-page followed by Coomassie staining and an anti-E. coli western blot. H107e had a recovery yield of 2.5 – 4.0 mg/L culture media, which was 2.5–5-fold higher than for H107. c Magnitude of IFN-γ T cell response (SFC/10⁶ PBMCs) in healthy QFT+ (n = 22) and QFT- (n = 10) subjects against H107 (blue dots) and H107e (orange dots). Dotted line indicates the limit of detection at 20 SFC/10⁶ PBMCs. Two-tailed unpaired t-test. d Bacterial burden in lung (left) and spleen (right) determined four weeks after aerosol challenge with Mtb Erdman in mice immunized with either 3xH107/CAF®01 or 3xH107e/CAF®01. Data plotted as mean ± SEM (n = 8). One-Way ANOVA with Tukey’s multiple comparisons test. One of two representative experiments shown. H107e-specific (e) and TB10.4-specific (f) IFN-γ response of splenocytes 6 weeks post immunizations with H107e doses ranging from 0.01 µg to 10 µg. Levels of IFN-γ shown as mean ± SEM (e) and as box plots showing median ± IQR with whiskers signifying the range of responses (f). Symbols indicate individual mice (n = 4). One-Way ANOVA with Fisher’s LSD for comparing H107e responses with or without BCG co-administration for each given H107e dose (e) and Tukey’s multiple comparison test for TB10.4 responses (f). g Lung bacterial burden at week three (left) and fourteen (right) post aerosol challenge with Mtb Erdman in mice H107e/CAF®01 immunized with or without BCG co-administration. Data plotted as mean ± SEM (n = 6–8); One-Way ANOVA with Tukey’s multiple comparisons test.