Fig. 3

Amoebal intoxication in hemagglutinin protease-deficient strains is caused by the PFT hemolysin (HlyA). a Aberrant amoebal morphotypes are caused by hemolysin (HlyA). Deletion of the hemolysin gene (hlyA) in the protease-minus V. cholerae strain (ΔhapAΔhlyA) nullifies intoxication of the amoebal trophozoites upon infection, while the latter is elicited through the overexpression of hlyA in the WT background (hlyA↑). All of the bacterial strains were GFP-tagged. Merged images of the transmitted light channel and the green channel were taken at 20 h p.p.c. Aberrantly shaped amoebae are indicated by white arrows. Scale bar: 10 µm b Absence of amoebal cellulose deposition is caused by hemolysin. A. castellanii cells were infected by the same V. cholerae strains as in a and, after staining with calcofluor, imaged at 30 h p.p.c. White arrows depict colonized amoebae that are calcofluor-negative and aberrantly shaped. Scale bar: 10 µm. c CLEM image of an amoeba that is infected by the protease-deficient and hemolysin-deficient V. cholerae strain