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Abstract

The reported incidence and mortality of -associated disease has increased significantly, which in part is likely to be due to the emergence of a new, highly virulent strain in North America and Europe. This epidemic strain, referred to as BI/NAP1/027, has increased virulence, attributed to overexpression of the two toxin-encoding genes, and , which may be due to truncation of the negative regulator () by a 1 bp deletion. In a previous study of whole-genome comparisons using microarray analysis of 75 isolates, it was noted that the 20 027 strains, which formed a hypervirulent clade, possessed a unique hybridization pattern for the 7 toxin B microarray reporters. This unique pattern was conserved in all of these 027 strains. The pattern was different for the 55 non-027 strains tested. These data, along with the knowledge that 027 strains are toxinotype III (i.e. possess a complete gene of comparable size to toxin reference strain VPI 10463), suggest that the sequence of the N-terminal binding domain of toxin B must be divergent from strain 630 (and the other 55 strains tested). Additionally, these 027 strains had comparable hybridization patterns across the whole microarray, as well as for . Therefore, it was suggested that they share a similar, novel N-terminal binding domain. The aim of this study was to ascertain the sequence variation in from eight characterized BI/NAP1/027 strains. The study confirmed significant sequence variation of from the sequenced strain 630 and slight variation in among the eight 027 strains. These results suggest that toxin B from 027 strains may have a different binding capacity compared with its less-virulent counterparts and may, in addition to the mutated regulator, be responsible for the increased virulence of 027 strains.

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/content/journal/jmm/10.1099/jmm.0.47743-0
2008-06-01
2025-05-14
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