CD8+ T cell adjuvant effects of Salmonella FliCd flagellin in live vaccine vectors or as purified protein

Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes, 1374, São Paulo, SP 05008-000, Brazil.
Vaccine (Impact Factor: 3.62). 11/2009; 28(5):1373-82. DOI: 10.1016/j.vaccine.2009.11.003
Source: PubMed


Salmonella flagellin, the flagellum structural subunit, has received particular interest as a vaccine adjuvant conferring enhanced immunogenity to soluble proteins or peptides, both for activation of antibody and cellular immune responses. In the present study, we evaluated the Salmonella enterica FliCd flagellin as a T cell vaccine adjuvant using as model the 9-mer (SYVPSAEQI) synthetic H2(d)-restricted CD8(+) T cell-specific epitope (CS(280-288)) derived from the Plasmodium yoelii circumsporozoite (CS) protein. The FliCd adjuvant effects were determined under two different conditions: (i) as recombinant flagella, expressed by orally delivered live S. Dublin vaccine strains expressing the target CS(280-288) peptide fused at the central hypervariable domain, and (ii) as purified protein in acellular vaccines in which flagellin was administered to mice either as a recombinant protein fused or admixed with the target CS(280-288) peptide. The results showed that CS(280-288)-specific cytotoxic CD8(+) T cells were primed when BALB/c mice were orally inoculated with the expressing the CS(280-288) epitope S. Dublin vaccine strain. In contrast, mice immunized with purified FliCd admixed with the CS(280-288) peptide and, to a lesser extent, fused with the target peptide developed specific cytotoxic CD8(+) T cell responses without the need of a heterologous booster immunization. The CD8(+) T cell adjuvant effects of flagellin, either fused or not with the target peptide, correlated with the in vivo activation of CD11c(+) dendritic cells. Taken together, the present results demonstrate that Salmonella flagellins are flexible adjuvant and induce adaptative immune responses when administered by different routes or vaccine formulations.

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Available from: Mauricio Rodrigues, Nov 24, 2014
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    • "This highlights the need to develop safe and efficacious mucosal adjuvants. Currently, the most promising adjuvants include the protein flagellin (FliC) and the subunit B of cholera toxin (CTB; Sanchez et al., 2004; Fingerut et al., 2005; Liu et al., 2010; Braga et al., 2010), which have shown capacity to augment immune responses with high levels of secretory IgA and of cytokines (Zhang et al., 2005; Sun et al., 2010; Chaung et al., 2012). Flagellin is the main structural protein of flagellae of Salmonella spp. "
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    ABSTRACT: This study investigated the immune response of broiler chickens with oral treatment of a Lactobacillus spp. pool (PL) associated with microencapsulated recombinant proteins flagellin (FliC) and the subunit B of cholera toxin (CTB). Immune responses were evaluated by measuring IgA from intestinal fluid, serum IgY, and immunostaining of CD8+ T lymphocytes present in the cecum. The evaluations were performed on d 0, 7, 14, 21, and 28 posttreatment. A significant increase (P < 0.05) was observed in IgA levels in all immunized groups, especially 3 wk after immunization. Treatments 2 (recombinant CTB) and 3 (recombinant FliC+CTB) showed the highest concentrations. Similarly, serum concentrations IgY (μg/mL) increased along the experiment, and the means for treatments 2 and 3 showed significant differences (P < 0.05) compared with controls, reaching concentrations of 533 and 540 μg/mL, respectively. The number of CD8+ T lymphocytes in all treatments greatly differed (P < 0.05) compared with the negative control at 21 d posttreatment. However, only treatment 2 (recombinant CTB), 4 (PL), and 5 (recombinant FliC+ recombinant CTB + PL) remained significantly (P < 0.05) different from the control at 28 d posttreatment. Thus, it is concluded that the microencapsulated recombinant proteins administered orally to broiler chickens are capable of stimulating humoral and cellular immune response, and the combinations of these antigens with Lactobacillus spp. can influence the population of CD8+ T cells residing in the cecum.
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    • "Besides, immunization with P. falciparum PfMSP119 fused to flagellin induced high antibody levels that efficiently inhibited the in vitro parasite growth [182]. Moreover, the CS280-288 protein (CD8+ T cell epitope from the CSP) from P. yoelii induced CS-specific CD8+ T cell responses when combined with flagellin and in the absence of any conventional adjuvant [183]. "
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    • "In addition, an increasing number of studies have demonstrated the adjuvant effects of flagellin [11], [12], [13], [14], [15], [16], including its ability to promote cytokine production through generalized recruitment of T and B lymphocytes and to activate dendritic cells and T lymphocytes through the Toll-like receptor (TLR) signaling pathway by the receptor TLR5 [14], [17]. In the mouse model, studies have also found that stimulation with flagellin resulted in substantial activation of murine bone marrow-derived dendritic cells (BMDCs) [18], [19], [20], [21]. "
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