Host-like carbohydrates promote bloodstream survival of Vibrio vulnificus in vivo.
Bottom Line: Sialic acids are found on all vertebrate cell surfaces and are part of a larger class of molecules known as nonulosonic acids.In fact, levels of bacterial persistence in the blood corresponded to the overall levels of these molecules expressed by V. vulnificus isolates.Taken together, these results suggest that molecules similar to sialic acids evolved to facilitate the aquatic lifestyle of V. vulnificus but that their emergence also resulted in a gain of function with life-threatening potential in the human host.
Affiliation: Department of Biological Sciences, University of Delaware, Newark, Delaware, USA.Show MeSH
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Mentions: To determine whether NulO molecules play a role in V. vulnificus systemic virulence, a tail vein injection model was used to directly administer bacteria to the bloodstream in CD1 mice. A spontaneously streptomycin-resistant isolate of the CMCP6 Δnab2 strain (Δnab2 Smr) was generated specifically for use in these experiments to distinguish mutant from WT bacteria during competition in vivo. This strain retained the phenotypes observed for the Δnab2 strain and did not vary from the parental strain in its growth characteristics in vitro (not shown). Strains were set up to compete against each other in a pairwise fashion, using a 1:1 mixed inoculum, to examine relative fitness levels. Blood was drawn at early time points postinfection, and the numbers of CFU of the strains were determined based on differential resistance to streptomycin. These experiments revealed that the nab2 gene confers a strong survival advantage to the WT strain in the bloodstream in vivo. The WT strain was present at approximately 5,000 CFU/ml of blood at 90 min postinfection, whereas the Δnab2 Smr strain was completely cleared by most animals at this time point (Fig. 4A).
Affiliation: Department of Biological Sciences, University of Delaware, Newark, Delaware, USA.