OVA 257 264 peptide (SIINFEKL)– CAS: 138831-86-4

Ovalbumin Epitope SIINFEKL Self-Assembles into a Supramolecular Hydrogel

Here we show that the well-known ovalbumin epitope SIINFEKL that is routinely used to stimulate ovalbumin-specific T cells and to test new vaccine adjuvants can form a stable hydrogel. We investigate properties of this hydrogel by a range of spectroscopic and imaging techniques demonstrating that the hydrogel is stabilized by self-assembly of the peptide into nanofibres via stacking of β-sheets. As peptide hydrogels are known to stimulate an immune response as adjuvants,the immunoactive properties of the SIINFEKL peptide may also originate from its propensity to self-assemble into a hydrogel. This finding requires a re-evaluation of this epitope in adjuvant testing.

A SIINFEKL-Based System to Measure MHC Class I Antigen Presentation Efficiency and Kinetics

BACKGROUND:

Antigen presentation by classical MHC class I molecules to CD8+ T cells is a central aspect of the adaptive immune response. Here,we describe methods to monitor antigen presentation using the model ovalbumin K^b-binding peptide,SIINFEKL. SIINFEKL genetically incorporated into viral or cellular source proteins can be used to precisely probe various aspects of antigen presentation,including the kinetics of peptide generation,MHC class I surface stability,and presentation efficiency following pharmacological and genetic manipulations including genome wide and high throughput drug screening.

Brucella Peptide Cross-Reactive Major Histocompatibility Complex Class I Presentation Activates SIINFEKL-Specific T Cell Receptor-Expressing T Cells

Brucella spp. are intracellular pathogenic bacteria remarkable in their ability to escape immune surveillance and therefore inflict a state of chronic disease within the host. To enable further immune response studies,Brucella was engineered to express the well-characterized chicken ovalbumin (OVA). Surprisingly,we found that CD8 T cells bearing T cell receptors (TCR) nominally specific for the OVA peptide SIINFEKL (OT-1) reacted to parental Brucella-infected targets as well as OVA-expressing Brucella variants in cytotoxicity assays. Furthermore,splenocytes from Brucella-immunized mice produced gamma interferon (IFN-γ) and exhibited cytotoxicity in response to SIINFEKL-pulsed target cells.To determine if the SIINFEKL-reactive OT-1 TCR could be cross-reacting to Brucella peptides,we searched the Brucella proteome using an algorithm to generate a list of near-neighbor nonamer peptides that would bind to H2Kb Selecting five Brucella peptide candidates,along with controls,we verified that several of these peptides mimicked SIINFEKL,resulting in T cell activation through the « SIINFEKL-specific » TCR. Activation was dependent on peptide concentration as well as sequence. Our results underscore the complexity and ubiquity of cross-reactivity in T cell recognition. This cross-reactivity may enable microbes such as Brucella to escape immune surveillance by presenting peptides similar to those of the host and may also lead to the activation of autoreactive T cells.

Synergistic activation of dendritic cells by combined Toll-like receptor ligation induces superior CTL responses in vivo

Toll-like receptors (TLRs) are able to interact with pathogen-derived products and their signals induce the coordinated activation of innate and adaptive immune mechanisms. Dendritic cells (DCs) play a central role in these events. As the different TLRs are able to trigger MyD88/TRIF-dependent and -independent signaling pathways,we wondered if the simultaneous activation of these signaling cascades would synergize with respect to DC activation and induce superior cytotoxic T-lymphocyte (CTL) activity in vivo. We observed that indeed the combined activation of MyD88-dependent and -independent signaling induced by TLR7 and TLR3 ligands provoked a more rapid and more sustained bone marrow-derived DC (BMDC) activation with regard to the secretion of proinflammatory cytokines,like IL-6 and IL-12p70,and the expression of costimulatory molecules like CD40,CD70,and CD86. Furthermore,in the presence of combined TLR ligand-stimulated DCs,CD4(+) and CD8(+) T cells were insensitive toward the inhibitory effects of regulatory T cells. Most importantly,peptide-loaded BMDCs stimulated by TLR ligand combinations resulted in a marked increase of CTL effector functions in wild-type mice in vivo. Thus,our results provide evidence that unlocking the full potential of DCs by advanced activation protocols will boost their immunogenic potential and improve DC-based vaccination strategies.