Funding Information: We thank Simon Cutting for the gift of the anti-CotD antibody and Aimee Shen for the gift of the anti-GerS and anti-GPR antibodies. We thank Georges Haustant for help with the spore cytopathic assays. This work was supported by grant PEst-OE/EQB/LA0004/2011 from the \u201CFunda\u00E7\u00E3o para a Ci\u00EAncia e a Tecnologia\u201D (FCT) to A.O.H. This work was also financially supported by ...