Host-like carbohydrates promote bloodstream survival of Vibrio vulnificus in vivo.
Bottom Line: Here we demonstrate that sialic acid-like molecules are present on the lipopolysaccharide of V. vulnificus, are required for full motility and biofilm formation, and also contribute to the organism's natural resistance to polymyxin B.Further experiments in a murine model of intravenous V. vulnificus infection demonstrated that expression of nonulosonic acids had a striking benefit for bacterial survival during bloodstream infection and dissemination to other tissues in vivo.In fact, levels of bacterial persistence in the blood corresponded to the overall levels of these molecules expressed by V. vulnificus isolates.
Affiliation: Department of Biological Sciences, University of Delaware, Newark, Delaware, USA.Show MeSH
Related in: MedlinePlus
Mentions: We previously observed that V. vulnificus strains with a CMCP6-like nab genotype had approximately 100-fold higher levels of NulO expression than strains with a YJ016-like genotype (24) (Fig. 5A). We next set out to measure the extent to which these two nab genotypes and their corresponding NulO phenotypes contribute to pathogenesis. To test the hypothesis that the CMCP6 strain may display a greater extent of nab2-dependent bloodstream survival and dissemination than YJ016, each of the WT strains were competed in parallel against their respective isogenic Δnab2 strains in the murine bacteremia model. Deletion of nab2 in the YJ016 background significantly reduced bacterial survival at 90 min postinfection when this strain competed against the WT YJ016 strain. Head-to-head comparison of nab2-dependent bloodstream survival revealed a pronounced, ∼50-fold difference in the competitive index between the two strain backgrounds (Fig. 5B). Whereas the CMCP6 strain outcompeted its Δnab2 derivative in the blood at 90 min postinfection, by about 500-fold (median, 508.3; n = 15), the YJ016 strain outcompeted its Δnab2 derivative by only about 10-fold (median, 11.22; n = 14). This finding strongly supports the interpretation that higher levels of NulO synthesis in connection with the CMCP6 nab genotype contribute to a greater capacity for bloodstream survival. These differences in nab2-dependent survival in blood in vivo also translate into differences in bacterial dissemination to other tissues, as evidenced by bacterial titers in the liver at 90 min postinfection (P < 0.001) (Fig. 5B).
Affiliation: Department of Biological Sciences, University of Delaware, Newark, Delaware, USA.