Affiliation:
1. Department of Microbiology-Immunology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA
2. Department of Microbiology and Environmental Toxicology, University of California at Santa Cruz, Santa Cruz, California, USA
Abstract
ABSTRACT
Vibrio cholerae
O1 El Tor strains have been responsible for pandemic cholera since 1961. These strains have evolved over time, spreading globally in three separate waves. Wave 3 is caused by altered El Tor (AET) variant strains, which include the strain with the signature
ctxB7
allele that was introduced in 2010 into Haiti, where it caused a devastating epidemic. In this study, we used phenotypic analysis to compare an early isolate from the Haiti epidemic to wave 1 El Tor isolates commonly used for research. It is demonstrated that the Haiti isolate has increased production of cholera toxin (CT) and hemolysin, increased motility, and a reduced ability to form biofilms. This strain also outcompetes common wave 1 El Tor isolates for colonization of infant mice, indicating that it has increased virulence. Monitoring of CT production and motility in additional wave 3 isolates revealed that this phenotypic variation likely evolved over time rather than in a single genetic event. Analysis of available whole-genome sequences and phylogenetic analyses suggested that increased virulence arose from positive selection for mutations found in known and putative regulatory genes, including
hns
and
vieA
, diguanylate cyclase genes, and genes belonging to the
lysR
and
gntR
regulatory families. Overall, the studies presented here revealed that
V. cholerae
virulence potential can evolve and that the currently prevalent wave 3 AET strains are both phenotypically distinct from and more virulent than many El Tor isolates.
Funder
Northwestern Medicine Catalyst Fund
HHS | NIH | National Institute of Allergy and Infectious Diseases
HHS | NIH | National Institute of Diabetes and Digestive and Kidney Diseases
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
48 articles.
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