The development of vaccines that protect against more than one strain is paramount to the defense against biowarfare agents and emerging infectious diseases as infection with several different strains may override the immunity elicited by a single vaccine, and pathogenic strains can develop in vaccinated individuals that make our current vaccines ineffective. The long-range objective of this proposal is to develop vaccines that are safe, and confer a potent state of cross-protective immunity against a variety of infectious agents. It has recently been established by us and others that S. typhimurium lacking a functional DNA adenine methylase (Dam) are significantly attenuated for virulence and elicit a potent state of protective immunity against challenge with the parental dam+ strain.
(AIM 1) We plan to evaluate how attenuated strains of S. typhimurium influence innate defenses of naive hosts, and how they influence professional antigen-presenting cells to present antigens to naive CD4+ and CD8+ T cells. We will also analyze whether oral vaccination with aroA, dam, aroA dam, Dam overproducing (DamOP), or aroA DamOP mutants of S. typhimurium will induce in naive hosts the presence of long lasting cell-mediated and humoral immune responses, both systemically and at the mucosal surfaces.
(AIM 2) The therapeutic index, or the ratio of the efficacy of the therapy over the toxicity, determines the success of Salmonella based vaccines. Currently, the most promising candidates include strains harboring mutations in genes whose products are involved in key biosynthetic pathways (aroA aroD), regulatory genes (cya crp and phoP phoQ), and genes encoding stress proteins (htrA) and combinations of these mutations. Here we propose to evaluate the safety and efficacy of dam mutant strains in combination with one or more of these attenuating mutations.
(AIM 3) Our data show that a single oral immunization of dam- or DamOP S. typhimurium elicits significant but incomplete cross-protective immunity to more than one Salmonella strain in murine and avian models of typhoid fever. We propose to determine if multiple immunizations of dam- or DamOP mutants, alone and in combination, can confer strong cross-protective immune responses against multiple Salmonella clinical isolates.
(AIM 4) The heightened immunity elicited by Salmonella dam mutant strains raises the possibility that passenger antigens from microbial infectious agents, when expressed by dam mutant vaccines, will elicit a protective immune response against the cognate pathogens. We will focus on the LcrV passenger antigen from Yersinia pseudotuberculosis since it is a known immunogen, and a virulence factor required for secretion of effector proteins into target cells and elicitation of pro-inhibitory responses. We propose to express Y. pseudotuberculosis LcrV in Salmonella dam mutant vaccines, and test whether vaccinated animals are protected against Y. pseudotuberculosis infection in a mouse model for Yersinia bacteremia.
|Enioutina, Elena Y; Bareyan, Diana; Daynes, Raymond A (2011) A role for immature myeloid cells in immune senescence. J Immunol 186:697-707|
|Enioutina, Elena Yu; Bareyan, Diana; Daynes, Raymond A (2009) TLR-induced local metabolism of vitamin D3 plays an important role in the diversification of adaptive immune responses. J Immunol 182:4296-305|
|Heithoff, Douglas M; Shimp, William R; Lau, Patrick W et al. (2008) Human Salmonella clinical isolates distinct from those of animal origin. Appl Environ Microbiol 74:1757-66|
|Enioutina, Elena Y; Bareyan, Diana; Daynes, Raymond A (2008) TLR ligands that stimulate the metabolism of vitamin D3 in activated murine dendritic cells can function as effective mucosal adjuvants to subcutaneously administered vaccines. Vaccine 26:601-13|
|Heithoff, Douglas M; Enioutina, Elena Y; Bareyan, Diana et al. (2008) Conditions that diminish myeloid-derived suppressor cell activities stimulate cross-protective immunity. Infect Immun 76:5191-9|
|Enioutina, Elena Y; Bareyan, Diana; Daynes, Raymond A (2007) Vitamin D3-mediated alterations to myeloid dendritic cell trafficking in vivo expand the scope of their antigen presenting properties. Vaccine 25:1236-49|
|Zhang, Tian Y; Daynes, Raymond A (2007) Glucocorticoid conditioning of myeloid progenitors enhances TLR4 signaling via negative regulation of the phosphatidylinositol 3-kinase-Akt pathway. J Immunol 178:2517-26|
|Simon, Raphael; Heithoff, Douglas M; Mahan, Michael J et al. (2007) Comparison of tissue-selective proinflammatory gene induction in mice infected with wild-type, DNA adenine methylase-deficient, and flagellin-deficient Salmonella enterica. Infect Immun 75:5627-39|
|Badie, Golnaz; Heithoff, Douglas M; Sinsheimer, Robert L et al. (2007) Altered levels of Salmonella DNA adenine methylase are associated with defects in gene expression, motility, flagellar synthesis, and bile resistance in the pathogenic strain 14028 but not in the laboratory strain LT2. J Bacteriol 189:1556-64|
|Heithoff, Douglas M; Badie, Golnaz; Julio, Steven M et al. (2007) In vivo-selected mutations in methyl-directed mismatch repair suppress the virulence attenuation of Salmonella dam mutant strains following intraperitoneal, but not oral, infection of naive mice. J Bacteriol 189:4708-17|