Figure 4. CwpV repeat types are antigenically distinct.

A. Cross-reactivity of C. difficile S-layer extracts from strains of different CwpV type. Recombinant CwpV domains were expressed and purified from E. coli for use as antigens. The domains used are illustrated by black lines above the cartoons of CwpV proteins. B. S-layer extracts from C. difficile strains analysed by SDS-PAGE illustrates the variability of S-layer proteins across strains, as previously described [11]. C. Western blot of S-layer extracts using anti-CwpVNter shows that this domain is recognized in all strains, as expected due to high sequence conservation. D. Western blots of S-layer extracts using antibodies against CwpV repeat types I–V show that each repeat-specific antibody only detects CwpV proteins containing at least one repeat of its own repeat type.