Cholera is a diarrheal disease caused by Vibrio cholerae that affects highly populated regions in Asia, Africa, and Latin America. In spite of significant efforts we still lack a vaccine that protects against both serogroups O1 and O139. Several live attenuated V. cholerae vaccine candidates still induced mild to moderate diarrhea in clinical trials. The reactogenicity of live vaccine candidates has been correlated with the capacity of attenuated vibrios to penetrate the protective mucus barrier. V. cholerae produces a metalloprotease: hemagglutinin/protease (Hap) encoded by hapA that has been associated with reactogenicity and promotes mucus penetration and detachment in vitro. We have demonstrated that expression of hapA requires the cyclic AMP receptor protein and the stationary phase sigma factor S.
The aim our study is to determine the mechanism by which quorum sensing regulators and stationary phase factors control expression of hapA in responses to environmental stimuli and to characterize the role hapA in pathogenesis. To this end we will construct and analyze regulatory mutants at the mRNA, protein and functional level. This study will contribute to a better understanding of the coordination between global regulatory networks in vibrios and other enteric pathogens. Experiments with mutants lacking Hap mucinolytic activity using cell culture, animal models, and volunteers suggest that mucinase production could perturb the protective mucus barrier, promote detachment, and cooperate with motility to spread the infection. In order to prove this hypothesis, we will construct mutants lacking mucinase activity and motility as well as double mutants. We will examine the effect of these mutations on virulence and colonization. Finally, we will use in vivo expression technology to determine the effect of Hap and motility inactivation on the expression of V. cholerae main virulence factors: cholera toxin and toxin co-regulated in the infant mouse intestine. This knowledge will facilitate the development of improved cholera vaccines.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI063187-03
Application #
7017099
Study Section
Special Emphasis Panel (ZAI1-GPJ-M (M1))
Program Officer
Hall, Robert H
Project Start
2004-09-01
Project End
2008-02-29
Budget Start
2006-03-01
Budget End
2007-02-28
Support Year
3
Fiscal Year
2006
Total Cost
$224,878
Indirect Cost
Name
Morehouse School of Medicine
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
102005451
City
Atlanta
State
GA
Country
United States
Zip Code
30310
Sultan, Syed Zafar; Silva, Anisia J; Benitez, Jorge A (2010) The PhoB regulatory system modulates biofilm formation and stress response in El Tor biotype Vibrio cholerae. FEMS Microbiol Lett 302:22-31
Ali, Syed A; Benitez, Jorge A (2009) Differential response of Vibrio cholerae planktonic and biofilm cells to autoinducer 2 deficiency. Microbiol Immunol 53:582-6
Liang, Weili; Sultan, Syed Zafar; Silva, Anisia J et al. (2008) Cyclic AMP post-transcriptionally regulates the biosynthesis of a major bacterial autoinducer to modulate the cell density required to activate quorum sensing. FEBS Lett 582:3744-50
Silva, Anisia J; Sultan, Syed Zafar; Liang, Weili et al. (2008) Role of the histone-like nucleoid structuring protein in the regulation of rpoS and RpoS-dependent genes in Vibrio cholerae. J Bacteriol 190:7335-45
Liang, Weili; Silva, Anisia J; Benitez, Jorge A (2007) The cyclic AMP receptor protein modulates colonial morphology in Vibrio cholerae. Appl Environ Microbiol 73:7482-7
Liang, Weili; Pascual-Montano, Alberto; Silva, Anisia J et al. (2007) The cyclic AMP receptor protein modulates quorum sensing, motility and multiple genes that affect intestinal colonization in Vibrio cholerae. Microbiology 153:2964-75
Jahid, Iqbal K; Silva, Anisia J; Benitez, Jorge A (2006) Polyphosphate stores enhance the ability of Vibrio cholerae to overcome environmental stresses in a low-phosphate environment. Appl Environ Microbiol 72:7043-9
Silva, Anisia J; Leitch, Gordon J; Camilli, Andrew et al. (2006) Contribution of hemagglutinin/protease and motility to the pathogenesis of El Tor biotype cholera. Infect Immun 74:2072-9
Silva, Anisia J; Benitez, Jorge A (2006) A Vibrio cholerae relaxed (relA) mutant expresses major virulence factors, exhibits biofilm formation and motility, and colonizes the suckling mouse intestine. J Bacteriol 188:794-800