Extended Data Fig. 4: Analyses of early proventricular infection and formation of cyst-like bodies.

a, Time course of infection up to five dpi with eGFP BSFs (J10 strain) using CLSM. Figure shows representative proventriculi and anterior midguts from each dpi. “Day 0”, proventriculus from a fly dissected 1 hr after receiving an infected meal. Black arrowhead at two dpi shows trypanosomes already in the proventriculus (see Supplementary Video 8). Scale bars 200 µm. b, TEM analysis of an early (five dpi) proventricular invasion by trypanosomes. Trypanosomes (T) can be seen near to the area of cell transition between the foregut (FG) and the proventricular/midgut epithelial cells (EC). At this time point the PV is heavily infected and parasites are located in the lumen (L), the ES and between PM layers. CI, cuticula intima. Scale bars left to right 2 µm, 2 µm and 10 µm. c, SEM analysis of an early (4 dpi) proventricular invasion by trypanosomes. (1), the tsetse PM is secreted by specialised cells near to the dorsal (Dors) side of the proventriculus (scale bar 100 µm). Trypanosomes can be seen within the immature PM (2; scale bar 10 µm) and also in the ectoperitrophic space (3, 4) after the PM has been pressed and hardened. Arrows on a dotted line represent PM path to the MG. Scale bar 10 µm and 1 µm respectively. Ant, anterior. Vent, ventral. FB, fat bodies. MG, midgut. d, TEM analysis of infected proventriculi from flies at eleven dpi. Parasites are contained within PM1 and PM2 or in the ES. No parasites can be seen within the lumen at this time point and the formation of cyst-like bodies can be observed. MV, microvilli. Scale bars left to right 2 µm, 5 µm and 20 µm. CLSM n=2 experiments, 10 flies dissected per timepoint.