As an Emergent Pathogen: Analyses of Phylogeny and O-antigen and Identification of Possible Virulence Characteristics

is an emergent pathogen that causes human infections which may be fatal. However, the phylogenetic characteristics and pathogenicity determinants of are poorly understood. Here, the whole-genome features of 103 strains isolated from different sources are described. On phylogenetic analysis populations could be divided into two major lineages, defined as lineage 1 (L1) and 2 (L2), of which L1 was more likely to be associated with human activity. Meanwhile, we defined 29 O-genotypes (VMOg, named VMOg1-VMOg29) by analysis of the O-antigen biosynthesis gene clusters (O-AGCs). Most VMOgs (VMOg1 to VMOg28) were assembled by the Wzx/Wzy pathway, while only VMOg29 used the ABC transporter pathway. Based on the sequence variation of the and genes, an O-genotyping system for was developed. Furthermore, nineteen virulence-associated factors involving 161 genes were identified within the genomes, including genes encoding motility, adherence, toxins, and secretion systems. In particular, was found to promote a high level of cytotoxicity through the synergistic action of the lateral flagella and T6SS. The lateral flagellar-associated gene played an important role in the adhesion and colonization of during the early stages of infection. Overall, this study provides an enhanced understanding of the genomic evolution, O-AGCs diversity, and potential pathogenic features of .