Flexible vs Rigid Epitope Conformations for Diagnostic- and Vaccine-Oriented Applications: Novel Insights from the Burkholderia pseudomallei BPSL2765 Pal3 Epitope.
Peptides seldom retain stable conformations if separated from their native protein structure. In an immunological context, this potentially affects the development of selective peptide-based bioprobes and, from a vaccine perspective, poses inherent limits in the elicitation of cross-reactive antibodies by candidate epitopes. Here, a 1,4-disubstituted-1,2,3-triazole-mediated stapling strategy was used to stabilize the native α-helical fold of the Pal3 peptidic epitope from the protein antigen PalBp (BPSL2765) from Burkholderia pseudomallei, the etiological agent of melioidosis. Whereas Pal3 shows no propensity to fold outside its native protein context, the engineered peptide (Pal3H) forms a stable α-helix, as assessed by MD, NMR, and CD structural analyses. Importantly, Pal3H shows an enhanced ability to discriminate between melioidosis patient subclasses in immune sera reactivity tests, demonstrating the potential of the stapled peptide for diagnostic purposes. With regard to antibody elicitation and related bactericidal activities, the linear peptide is shown to elicit a higher response. On these bases, we critically discuss the implications of epitope structure engineering for diagnostic- and vaccine-oriented applications.
Istituto di Chimica del Riconoscimento Molecolare, Consiglio Nazionale delle Ricerche, Via Mario Bianco, 9, 20131, Milan, Italy.
Alessandro
A
Gori
Istituto di Chimica del Riconoscimento Molecolare, Consiglio Nazionale delle Ricerche, Via Mario Bianco, 9, 20131, Milan, Italy.
Claudio
C
Peri
Biomolecular NMR Laboratory, Division of Genetics and Cell Biology, S. Raffaele Scientific Institute, 20132 Milan, Italy.
Giacomo
G
Quilici
Center for Research and Development of Medical Diagnostic Laboratories (CMDL), Faculty of Associated Medical Sciences, Khon Kaen University , 40002, Khon Kaen, Thailand.
Arnone
A
Nithichanon
Biomolecular NMR Laboratory, Division of Genetics and Cell Biology, S. Raffaele Scientific Institute, 20132 Milan, Italy.
Davide
D
Gaudesi
Istituto di Chimica del Riconoscimento Molecolare, Consiglio Nazionale delle Ricerche, Via Mario Bianco, 9, 20131, Milan, Italy.
Renato
R
Longhi
Department of Biosciences, University of Milan , 20133, Milan, Italy.
Louise
L
Gourlay
Department of Biosciences, University of Milan , 20133, Milan, Italy.|CNR-IBF and Cimaina, c/o Department of Biosciences, University of Milan , 20133, Milan, Italy.
Martino
M
Bolognesi
Center for Research and Development of Medical Diagnostic Laboratories (CMDL), Faculty of Associated Medical Sciences, Khon Kaen University , 40002, Khon Kaen, Thailand.
Ganjana
G
Lertmemongkolchai
Biomolecular NMR Laboratory, Division of Genetics and Cell Biology, S. Raffaele Scientific Institute, 20132 Milan, Italy.
Giovanna
G
Musco
Istituto di Chimica del Riconoscimento Molecolare, Consiglio Nazionale delle Ricerche, Via Mario Bianco, 9, 20131, Milan, Italy.
Giorgio
G
Colombo
D000907:Antibodies, Bacterial / Q000276:immunology; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D001428:Bacterial Vaccines / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D016957:Burkholderia pseudomallei / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D018360:Crystallography, X-Ray; D000939:Epitopes / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D006801:Humans; D008554:Melioidosis / Q000175:diagnosis* / Q000276:immunology / Q000382:microbiology
D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D000939:Epitopes
antigen design; bioprobes; epitope engineering; melioidosis; peptide stapling; structural vaccinology