Fig. 6: Close interactions between T. muris whipworm larvae and IECs at syncytial tunnels during early infection of caecaloids.

a Selected confocal IF 2D images from a z-stack showing IECs left behind in the tunnel are necrotic (propidium iodide (red) and caspase-3/7 (green) positive), while IECs infected by worm are alive after 72 h p.i. In blue and aqua, DAPI stains nuclei of IECs and larvae, respectively; and in white, phalloidin binds to F-actin. Scale bars 50 μm. b–d Representative TEM images of transverse sections of caecaloids infected with T. muris L1 larvae, showing host-parasite interactions during early infection: b Host cell actin fibres (white arrowhead) surround the cuticle of the worm (inset I) and desmosomes (red asterisks) are still present (inset II) at 24 h p.i. c Liquefied cell (inset I, asterisk), and nuclei in early stages of apoptosis (inset II) at 72 h p.i. d Displaced mitochondria (inset I) and numerous lysosomes in host cells, some actively discharging over the worm cuticle (insets II and III). N, nuclei; red asterisks, lysosomes. TEM images are representative of 10 larvae during the first 72 h of infection. Imaging experiments on T. muris-infected caecaloids were done in triplicate across more than ten independent replicas using three caecaloid lines derived from three C57BL/6 mice.