The underlying hypothesis of this research plan is that it will be possible, by appropriate manipulation of attenuated Salmonella typhi and Shigella live vectors, to develop a mucosally administered multivalent vaccine to prevent Plasmodium falciparum malaria. Proving the broad hypothesis requires that we adapt an attenuated Shigella vaccine strain to deliver eukaryotic expression plasmid-based """"""""naked"""""""" DNA (hereafter referred to as DNA vaccine) via mucosal immunization, thereby priming the immune system to recognize P. falciparum antigens. We will then attempt to boost the immune response by administering via mucosal immunization attenuated S. typhi live vectors expressing protective antigens from the sporozoite, liver, and asexual erythrocytic stages of P. falciparum life cycle. When using such a """"""""prime/boost"""""""" strategy in animals by priming with parenteral DNA vaccine and then boosting parenterally with a live vector expressing the relevant antigen, the immune responses and the level of protection elicited markedly exceeds that achieved when either DNA or live vector is used for both prime and boost, or when protein is used to boost following priming with DNA. The efficacy of DNA prime/live vector boost has been particularly impressive with Plasmodium antigens. To optimize the priming potential of Shigella live vectors harboring DNA vaccines, we propose to use DNA vaccines in which codon usage has been optimized for expression by mammalian (human) cells. We also propose to optimize the boosting potential of S. typhi live vectors carrying prokaryotic expression plasmids at two independent levels: 1] modifying the codon usage within falciparum open reading frames for optimum expression within S. typhi live vectors; and 2] exploiting a recently developed S. typhi plasmid maintenance system which employs partition and post-segregational killing functions, to maintain codon-optimized expression plasmids. Since we propose to study Plasmodium genes encoding CSP, LSA-1, SSP2, and MSP-1, we will examine the equivalence of priming with a mixture of four Shigella live vector strains, each carrying a plasmid encoding a distinct P. falciparum antigen, versus immunization with each individual live vector; we will also examine the equivalence of boosting with S. typhi either as a combination vaccine or as separate constructs. We hypothesize that by independently attaining partial protection against further development of each of the stages of P. falciparum, and by these effects working in concert, we will ultimately be able to prevent disease completely in some subjects and to markedly ameliorate disease severity in others.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
2R01AI040297-04
Application #
6192875
Study Section
Special Emphasis Panel (ZRG1-VACC (01))
Program Officer
Hall, B Fenton
Project Start
1997-04-01
Project End
2005-06-30
Budget Start
2000-07-01
Budget End
2001-06-30
Support Year
4
Fiscal Year
2000
Total Cost
$371,250
Indirect Cost
Name
University of Maryland Baltimore
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
003255213
City
Baltimore
State
MD
Country
United States
Zip Code
21201
Galen, James E; Pasetti, Marcela F; Tennant, Sharon et al. (2009) Salmonella enterica serovar Typhi live vector vaccines finally come of age. Immunol Cell Biol 87:400-12
Chinchilla, Magaly; Pasetti, Marcela F; Medina-Moreno, Sandra et al. (2007) Enhanced immunity to Plasmodium falciparum circumsporozoite protein (PfCSP) by using Salmonella enterica serovar Typhi expressing PfCSP and a PfCSP-encoding DNA vaccine in a heterologous prime-boost strategy. Infect Immun 75:3769-79
Vindurampulle, Christofer J; Cuberos, Lilian F; Barry, Eileen M et al. (2004) Recombinant Salmonella enterica serovar Typhi in a prime-boost strategy. Vaccine 22:3744-50
Pasetti, Marcela F; Levine, Myron M; Sztein, Marcelo B (2003) Animal models paving the way for clinical trials of attenuated Salmonella enterica serovar Typhi live oral vaccines and live vectors. Vaccine 21:401-18
Gomez-Duarte, O G; Pasetti, M F; Santiago, A et al. (2001) Expression, extracellular secretion, and immunogenicity of the Plasmodium falciparum sporozoite surface protein 2 in Salmonella vaccine strains. Infect Immun 69:1192-8
Wang, J Y; Pasetti, M F; Noriega, F R et al. (2001) Construction, genotypic and phenotypic characterization, and immunogenicity of attenuated DeltaguaBA Salmonella enterica serovar Typhi strain CVD 915. Infect Immun 69:4734-41
Orr, N; Galen, J E; Levine, M M (2001) Novel use of anaerobically induced promoter, dmsA, for controlled expression of fragment C of tetanus toxin in live attenuated Salmonella enterica serovar Typhi strain CVD 908-htrA. Vaccine 19:1694-700
Levine, M M (2000) Immunization against bacterial diseases of the intestine. J Pediatr Gastroenterol Nutr 31:336-55
Tacket, C O; Sztein, M B; Wasserman, S S et al. (2000) Phase 2 clinical trial of attenuated Salmonella enterica serovar typhi oral live vector vaccine CVD 908-htrA in U.S. volunteers. Infect Immun 68:1196-201
Pasetti, M F; Pickett, T E; Levine, M M et al. (2000) A comparison of immunogenicity and in vivo distribution of Salmonella enterica serovar Typhi and Typhimurium live vector vaccines delivered by mucosal routes in the murine model. Vaccine 18:3208-13

Showing the most recent 10 out of 19 publications