, 2007). The serogroup O:28 (formerly M) of the Kauffmann-White scheme (Grimont & Weill, 2007) consists

of 107 serovars of Salmonella, which have only the epitope O28 divided into three subfactors – O281, O282 and O283 – but without any differences identified (Lindberg & Le Minor, 1984). Salmonella Dakar (S. Dakar) has subfactors O281 and O283, whereas Salmonella Telaviv (S. Telaviv) possesses O281 and O282. Up till now, the structures of the repeating units of only two O-polysaccharides – S.  Dakar (Kumirska et al., 2007) and S. Telaviv (Kumirska et al., 2011) – have been established. Both O-antigens contain untypical sugar 3-acetamido-3,6-dideoxy-glucose (Quip3NAc), found also in other Gram-negative bacteria (Raff & Wheet, 1967; Raff & Wheat, 1968). In preparing O-antigen-immune sera for the identification of S. Telaviv and S. Dakar serovars, rabbits are immunized with these bacteria and the sera obtained are absorbed by Salmonella RG7420 molecular weight Champaign (O:39) and Salmonella II 39:l,z28:e,n,x (39) (Lindberg & Le Minor, 1984). A control test should give a negative cross-reaction

with bacteria belonging to serogroups C1, C2, D (122+), Ipilimumab clinical trial O:30, O:35 and O:39. Literature data on the serological and immunological properties of this serogroup are very limited. Lüderitz et al. studied the cross-reactions of S. Dakar and S. Telaviv with Citrobacter freundii 8090 and Citrobacter freundii 869 using unabsorbed and absorbed test sera (Lüderitz et al., 1967; Keleti & Lüderitz, 1971). They observed that Citrobacter freundii 8090 cross-reacts only with sera containing antibodies against 283 factor, whereas Citrobacter freundii 869 behaves like S. Dakar, cross-reacting with those sera containing antibodies against factor either 281 or 283. The LPSs of both bacteria cross-react with S. Champaign (serogroup O:39) and Salmonella Frankfurt HSP90 (serogroup O:16). Allen & Pazur (1984) analysed the interaction of S. Telaviv LPS with its lipid A free polysaccharide with polymeric McPC 870 and MOPC 384 mouse IgA myeloma proteins. Inhibition data suggest that this interaction can be mediated by galactose and/or glucose units

of cross-reactive antigens. A close relationship between Escherichia coli O71 and S. enterica O28 O-antigens (represented by S. Dakar) was found by Hu et al. (2010). The serogroup-specific genes of E. coli O71 and S. enterica O28 were established, and the structural similarity between the E. coli O71 and S. Dakar O-antigen structures was presented. Clark et al. (2010) reported that the O-antigen gene cluster of S. Dakar was quite different from that of Salmonella Pomona (O281, O282), although these serovars belonged to the same O-serogroup. This study describes the immunochemical investigations of the Salmonella Telaviv (S. Telaviv OPS) and S. Dakar (S. Dakar OPS) O-antigens using polyclonal sera and monoclonal antibodies (MAbs) against O281.