The genome of non-O1 Vibrio cholerae NRT36S demonstrates the presence of pathogenic mechanisms that are distinct from those of O1 Vibrio cholerae

Abstract

Vibrio cholerae NRT36S is a non-cholera toxin-producing, non-O1 strain that causes diarrhea in volunteers. The genome of NRT36S was sequenced to create a draft containing 174 contigs plus the superintegron region. Our analysis of the draft genome revealed several putative toxin genes and colonization factors. Besides confirming the existence of nonagglutinable heat-stable toxin, we also identified the genes for a type three secretion system, a putative exotoxin, two different RTX toxins, and four pilus systems.

FIG. 1.

Comparison of V. cholerae N16961 and NRT36S genomes. The two closed rings represent two chromosomes of N16961. Chromosome I is on the left, and chromosome II is on the right. The white areas in the rings are sequences conserved between the two genomes. Gray areas are sequences specific to N16961, with labels inside the rings. Black areas outside the rings are sequences specific to NRT36S, with labels outside the rings. VSP-I and VSP-II, Vibrio seventh pandemic islands I and II; LPS, lipopolysaccharide; VPI-1 and VPI-2, Vibrio pathogenic islands 1 and 2; CTX, cholera toxin genes; PTS, phosphoenolpyruvate phosphotransferase system; CPS, capsule polysaccharide; TTSS, type III secretion system; TRH, thermostable direct hemolysin; SI, superintegron.

FIG. 2.

Mosaic pattern of Vibrio pathogenic island 2. The three regions in the Vibrio pathogenic island were described previously (8). White boxes are conserved regions between N16961 and NRT36S. Shaded boxes indicate genes specific to N16961. The hatched box indicates genes specific to NRT36S.