: A novel gene variant encoding Nhe was identified in these three strains, which had an
average of 80% identity in protein sequence with previously identified Nhe toxins. While culture
supernatants containing CytK and Nhe from NVH 391/98 and INRA AF2 were highly cytotoxic,
NVH 883/00 expressed little or no CytK and Nhe and was non-cytotoxic. Comparative sequence
and expression studies indicated that neither the PlcR/PapR quorum sensing system, nor theYvrGH
and YvfTU two-component systems, were responsible for the observed difference in toxin
production. Additionally, phylogenetic analysis of 13 genes showed that NVH 391/98, NVH 883/00,
and INRA AF2 comprise a novel cluster of strains genetically distant from other B. cereus group
strains