This proposal addresses several related aspects of a research problem with significant potential to influence the management of infectious diseases on a large scale, not only for vaccines against enteric bacterial pathogens, but also for vaccines against a variety of other bacteria, viruses, and parasites. The central theme of this project is for the use of attenuated mutants of Salmonella as immunologic vehicles to deliver heterologous antigens to the mucosal lymphoid tissues. This has been shown to be an effective means of stimulating significant levels of serum and mucosal antibodies as well as cell mediated immunity against the carrier and against foreign antigens delivered by these organisms. During the current funding cycle, we have addressed several broad issues relative to the use of this technique of vaccine delivery. There are, however, a number of fundamental questions remaining to be answered regarding the use of Salmonella as a vaccine carrier. When attenuated Salmonella sp. are utilized as carriers of foreign antigens, an undefined series of events occurs which can result in production of antigen specific mucosal sIgA, serum IgG, cell mediated immunity, or combinations of these immunologic events. We propose to examine a number of specific parameters that will enable us to begin to understand the mechanisms underlying these outcomes. For this competitive renewal, we propose to resolve the underlying mechanisms controlling the immunologic outcome as a function of bacterial attenuation, strain viability, bacterial species, pre-existing immunity, and qualitative and quantitative nature of the target antigen. For these experiments, animals will be inoculated orally and examined for antigen specific humoral and cellular immune responses. Isotype analysis of antigen specific antibodies from sera and mucosa will be performed by ELISA. Cellular responses will be determined by l) PCR to amplify reverse transcribed cytokine mRNAs expressed by leukocytes in vivo and 2) ELISA to determine cytokine secretion from antigen specific lymphocytes in vitro. These experiments should permit the design of specifically tailored Salmonella vaccine delivery systems according to the type and character of immune response appropriate for the target pathogen (i.e., CMI for intracellular bacteria vs. sIgA for mucosal response). In addition, we will more fully examine the issue of bacterial persistence in the tissues as a determinant of the cellular and humoral immune response and complete our studies on development of a mouse model for ETEC diarrheal disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
2R01AI028835-04
Application #
3143428
Study Section
Bacteriology and Mycology Subcommittee 2 (BM)
Project Start
1990-07-01
Project End
1998-06-30
Budget Start
1993-07-01
Budget End
1994-06-30
Support Year
4
Fiscal Year
1993
Total Cost
Indirect Cost
Name
Tulane University
Department
Type
Schools of Medicine
DUNS #
City
New Orleans
State
LA
Country
United States
Zip Code
70118
Ryan, E T; Crean, T I; John, M et al. (1999) In vivo expression and immunoadjuvancy of a mutant of heat-labile enterotoxin of Escherichia coli in vaccine and vector strains of Vibrio cholerae. Infect Immun 67:1694-701
Freytag, L C; Clements, J D (1999) Bacterial toxins as mucosal adjuvants. Curr Top Microbiol Immunol 236:215-36
Chong, C; Friberg, M; Clements, J D (1998) LT(R192G), a non-toxic mutant of the heat-labile enterotoxin of Escherichia coli, elicits enhanced humoral and cellular immune responses associated with protection against lethal oral challenge with Salmonella spp. Vaccine 16:732-40
Toebe, C S; Clements, J D; Cardenas, L et al. (1997) Evaluation of immunogenicity of an oral Salmonella vaccine expressing recombinant Plasmodium berghei merozoite surface protein-1. Am J Trop Med Hyg 56:192-9
Bost, K L; Clements, J D (1997) Intracellular Salmonella dublin induces substantial secretion of the 40-kilodalton subunit of interleukin-12 (IL-12) but minimal secretion of IL-12 as a 70-kilodalton protein in murine macrophages. Infect Immun 65:3186-92
Guidry, J J; Cardenas, L; Cheng, E et al. (1997) Role of receptor binding in toxicity, immunogenicity, and adjuvanticity of Escherichia coli heat-labile enterotoxin. Infect Immun 65:4943-50
Chong, C; Bost, K L; Clements, J D (1996) Differential production of interleukin-12 mRNA by murine macrophages in response to viable or killed Salmonella spp. Infect Immun 64:1154-60
Bost, K L; Holton, R H; Cain, T K et al. (1996) In vivo treatment with anti-interleukin-13 antibodies significantly reduces the humoral immune response against an oral immunogen in mice. Immunology 87:633-41
Kincy-Cain, T; Clements, J D; Bost, K L (1996) Endogenous and exogenous interleukin-12 augment the protective immune response in mice orally challenged with Salmonella dublin. Infect Immun 64:1437-40
Bost, K L; Clements, J D (1995) In vivo induction of interleukin-12 mRNA expression after oral immunization with Salmonella dublin or the B subunit of Escherichia coli heat-labile enterotoxin. Infect Immun 63:1076-83

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