FN1 and infection: Spores of the C. difficile ΔbclA3 mutant strain exhibited a significant decrease in spore entry into Caco-2 cells, but not adherence to monolayers of Caco-2 cells was observed upon infection with C. difficile spores ΔbclA3 mutant in the presence of Fn (Fig. 5f, g) and Vn (Fig. 5h, i).