Genetic Analysis and Serological Detection of Novel O-Antigen Gene Clusters of .

, a member of the family , is a gram-negative, rod-shaped, facultative anaerobic bacterium with flagella. has been isolated from such sources as freshwater, surface water, and many wild and domestic animals. contains 102 Oantigens and 51 H-antigens. The diversity of O-antigen gene clusters is relatively poorly understood. In addition to O1 and O17 reported by other laboratories, and the 12 O serogroups (O2, O10, O12, O23, O25, O26, O32, O33, O34, O66, O75, and O76) reported previously by us, in the present study, nine new serogroups (O8, O17, O18, O37, O38, O39, O44, O45, and O61) were sequenced and annotated. The genes for the O-antigens of these nine groups are clustered together in the chromosome between and . Only O38 possesses the and genes for the synthesis and translocation of O-antigens via the ATP-binding cassette (ABC) transporter pathway; the other eight use the Wzx/Wzy pathway. Phylogenetic analysis using and showed that both genes are diversified. Among the nine new serogroups, eight use genes as targets. In addition, we developed an O-antigen-specific PCR assay to detect these nine distinct serogroups with no cross reactions among them.