Cross reactivity between Y. enterocolitica O:9 and Brucella spp. LPS samples. (0.2 OD/sample loaded) on 15% SDS-PAGE: A) LPS silver stain analysis of samples of Y. enterocolitica 1) OC-/HP-, 2)HP-, 3) OC-, 4) WT; Brucella 5) B. abortus, 6) B. melintensis, and 7) B. suis. B) Immunoblot against the same samples with monoclonal α-Yersinia (Yst 9-2). C) Immunoblot of the same samples using monoclonal α-Brucella (M84). Cross reactivity between the two different genus' LPS is observed by both monoclonal antibodies reacting against the higher molecular weight homopolymeric N-formylperosamine polysaccharide.