Antigen Biological Propertiesa Immunological Propertiesb   Cell-binding   HA activity   Cell entry Elicit neutralizing antibodies Elicit protection in hamster model Activate dendritic cell TcdA TcdB TcdA RBD 50 nM 0.4 pmoles Fast 256 <4 No 0.4 µM TcdB RBD 100 nM No Fast 16 64 No 1 µM TcdB Yes** NP Yes NP Yes NP NP aResults are from a previous [31] and the current studies bThe immunogenicity studies of TcdA RBD will be published elsewhere *NP means not performed **Yes refers to information from the literature [7-23,31].

Table 2: Summary of biochemical and immunological properties of TcdA RBD and TcdB RBD.