Vibrio cholerae is a facultative pathogen and the causative agent of cholera. Hallmarks of the disease include profuse watery diarrhea resulting from the action of secreted cholera toxin, and deadly, explosive outbreaks. The strong link between epidemics and human overcrowding in areas with untreated drinking water suggests an efficient mode of fecal-oral transmission via an aquatic intermediate. In support of this notion, we discovered that V. cholerae exit cholera victims in a heightened state of transmissibility (referred to as "hyperinfectivity"), which persists for several hours after shedding into pond water. Knowledge of the molecular basis for this phenotype, and a general characterization of this transmissible form of V. cholerae, would contribute to the design of vaccines to prevent cholera at the initial stage of infection. In prior work, we discovered that motility in the absence of chemotaxis is one determinant of hyperinfectivity. To identify additional determinants aiding in transmission, we measured global transcriptional changes in human-shed V. cholerae during the transition to an aquatic microcosm. This analysis revealed a number of regulators and effectors that potentially contribute to cholera transmission. In related work, we used a genetic selection to identify genes that are `pre-induced'at late stages of infection and which subsequently play roles in the transition of V. cholerae to aquatic environments.
In Aims 1 and 2 of this project, we propose to determine if genes regulated late in infection or in cholera stool play important roles in the transition to pond water and in hyperinfectivity. Transcriptional regulators with important roles in these phenotypes will be further analyzed by transcriptional profiling to define their corresponding regulons.
In Aim 2, we also propose to measure and correlate changes in the transcriptome and proteome of cholera stool V. cholerae during the transition to pond water.
In Aim 3, we propose to apply knowledge of the effectors of transmission to develop and test a mucosal vaccine in a mouse maternal model of immunization and challenge of pups. We hypothesize that an acellular vaccine expressing a repertoire of antigens that are stably expressed on the surface of transmissible forms of V. cholerae will provide enhanced protection to challenge by the transmissible form of this pathogen. These studies will establish a basis for understanding both the hyperinfective phenotype of V. cholerae and its transition to aquatic environments. This knowledge will enhance our understanding of transmission of this and perhaps other water-borne pathogens, helping pave the way to development of novel vaccines that target transmissible forms of facultative pathogens.

Public Health Relevance

Many of the diseases that afflict humans are caused by microbes transmitted via contaminated water supplies. The biology of pathogens in aquatic reservoirs and the traits they have evolved to aid in their transmission are largely unknown. Our project will use the causative agent of cholera as a model pathogen to uncover such evolved traits, and will use the knowledge gained to test a novel vaccine that targets the transmissible form of the pathogen.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Bacterial Pathogenesis Study Section (BACP)
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Hall, Robert H
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Tufts University
Schools of Medicine
United States
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McDonough, Emilykate; Lazinski, David W; Camilli, Andrew (2014) Identification of in vivo regulators of the Vibrio cholerae xds gene using a high-throughput genetic selection. Mol Microbiol 92:302-15
Dalia, Ankur B; McDonough, EmilyKate; Camilli, Andrew (2014) Multiplex genome editing by natural transformation. Proc Natl Acad Sci U S A 111:8937-42
Seed, Kimberley D; Yen, Minmin; Shapiro, B Jesse et al. (2014) Evolutionary consequences of intra-patient phage predation on microbial populations. Elife 3:e03497
van Opijnen, Tim; Lazinski, David W; Camilli, Andrew (2014) Genome-Wide Fitness and Genetic Interactions Determined by Tn-seq, a High-Throughput Massively Parallel Sequencing Method for Microorganisms. Curr Protoc Mol Biol 106:7.16.1-7.16.24
Bishop, Anne L; Patimalla, Bharathi; Camilli, Andrew (2014) Vibrio cholerae-induced inflammation in the neonatal mouse cholera model. Infect Immun 82:2434-47
Dalia, Ankur B; Lazinski, David W; Camilli, Andrew (2013) Characterization of undermethylated sites in Vibrio cholerae. J Bacteriol 195:2389-99
Seed, Kimberley D; Lazinski, David W; Calderwood, Stephen B et al. (2013) A bacteriophage encodes its own CRISPR/Cas adaptive response to evade host innate immunity. Nature 494:489-91
Lazinski, David W; Camilli, Andrew (2013) Homopolymer tail-mediated ligation PCR: a streamlined and highly efficient method for DNA cloning and library construction. Biotechniques 54:25-34
Bishop, Anne L; Tarique, Abdullah A; Patimalla, Bharathi et al. (2012) Immunization of mice with vibrio cholerae outer-membrane vesicles protects against hyperinfectious challenge and blocks transmission. J Infect Dis 205:412-21
Seper, Andrea; Fengler, Vera H I; Roier, Sandro et al. (2011) Extracellular nucleases and extracellular DNA play important roles in Vibrio cholerae biofilm formation. Mol Microbiol 82:1015-37

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