Extracellular Loops of the Treponema pallidum FadL Orthologs TP0856 and TP0858 Elicit IgG Antibodies and IgG + -Specific B-Cells in the Rabbit Model of Experimental Syphilis.

Autor:	Delgado KN; Department of Medicine, UConn Health, Farmington, Connecticut, USA., Montezuma-Rusca JM; Department of Medicine, UConn Health, Farmington, Connecticut, USA.; Division of Infectious Diseases, UConn Health, Farmington, Connecticut, USA.; Department of Pediatrics, UConn Health, Farmington, Connecticut, USA., Orbe IC; Department of Pediatrics, UConn Health, Farmington, Connecticut, USA., Caimano MJ; Department of Medicine, UConn Health, Farmington, Connecticut, USA.; Department of Pediatrics, UConn Health, Farmington, Connecticut, USA.; Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA., La Vake CJ; Department of Pediatrics, UConn Health, Farmington, Connecticut, USA., Luthra A; Department of Medicine, UConn Health, Farmington, Connecticut, USA.; Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA., Hennelly CM; Division of Infectious Diseases, Department of Medicine, and Institute for Global Health and Infectious Diseases, University of North Carolina, Chapel Hill, North Carolina, USA., Nindo FN; Division of Infectious Diseases, Department of Medicine, and Institute for Global Health and Infectious Diseases, University of North Carolina, Chapel Hill, North Carolina, USA., Meyer JW; Duke Human Vaccine Institute, Durham, North Carolina, USA., Jones LD; Duke Human Vaccine Institute, Durham, North Carolina, USA., Parr JB; Division of Infectious Diseases, Department of Medicine, and Institute for Global Health and Infectious Diseases, University of North Carolina, Chapel Hill, North Carolina, USA., Salazar JC; Department of Pediatrics, UConn Health, Farmington, Connecticut, USA.; Division of Infectious Diseases and Immunology, Connecticut Children's, Hartford, Connecticut, USA.; Department of Immunology, UConn Health, Farmington, Connecticut, USA., Moody MA; Duke Human Vaccine Institute, Durham, North Carolina, USA.; Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA.; Department of Immunology, Duke University Medical Center, Durham, North Carolina, USA., Radolf JD; Department of Medicine, UConn Health, Farmington, Connecticut, USA.; Department of Pediatrics, UConn Health, Farmington, Connecticut, USA.; Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA.; Department of Immunology, UConn Health, Farmington, Connecticut, USA.; Department of Genetics and Genome Sciences, UConn Health, Farmington, Connecticut, USA., Hawley KL; Department of Medicine, UConn Health, Farmington, Connecticut, USA.; Department of Pediatrics, UConn Health, Farmington, Connecticut, USA.; Division of Infectious Diseases and Immunology, Connecticut Children's, Hartford, Connecticut, USA.
Jazyk:	angličtina
Zdroj:	MBio [mBio] 2022 Aug 30; Vol. 13 (4), pp. e0163922. Date of Electronic Publication: 2022 Jul 12.
DOI:	10.1128/mbio.01639-22
Abstrakt:	The resurgence of syphilis in the new millennium has called attention to the importance of a vaccine for global containment strategies. Studies with immune rabbit serum (IRS) indicate that a syphilis vaccine should elicit antibodies (Abs) that promote opsonophagocytosis of treponemes by activated macrophages. The availability of three-dimensional models for Treponema pallidum's ( Tp ) repertoire of outer membrane proteins (OMPs) provides an architectural framework for identification of candidate vaccinogens with extracellular loops (ECLs) as the targets for protective Abs. Herein, we used Pyrococcus furiosus thioredoxin ( Pf Trx) as a scaffold to display Tp OMP ECLs to interrogate sera and peripheral blood mononuclear cells (PBMCs) from immune rabbits for ECL-specific Abs and B cells. We validated this approach using a Pf Trx scaffold presenting ECL4 from BamA, a known opsonic target. Using scaffolds displaying ECLs of the FadL orthologs TP0856 and TP0858, we determined that ECL2 and ECL4 of both proteins are strongly antigenic. Comparison of ELISA and immunoblot results suggested that the Pf Trx scaffolds present conformational and linear epitopes. We then used the FadL ECL2 and ECL4 Pf Trx constructs as "hooks" to confirm the presence of ECL-specific B cells in PBMCs from immune rabbits. Our results pinpoint immunogenic ECLs of two newly discovered OMPs, while advancing the utility of the rabbit model for circumventing bottlenecks in vaccine development associated with large-scale production of folded OMPs. They also lay the groundwork for production of rabbit monoclonal Abs (MAbs) to characterize potentially protective ECL epitopes at the atomic level. IMPORTANCE Recent identification and structural modeling of Treponema pallidum's ( Tp ) repertoire of outer membrane proteins (OMPs) represent a critical breakthrough in the decades long quest for a syphilis vaccine. However, little is known about the antigenic nature of these β-barrel-forming OMPs and, more specifically, their surface exposed regions, the extracellular loops (ECLs). In this study, using Pyrococcus furiosus thioredoxin ( Pf Trx) as a scaffold to display Tp OMP ECLs, we interrogated immune rabbit sera and peripheral blood mononuclear cells for the presence of antibodies (Abs) and circulating rare antigen-specific B cells. Our results pinpoint immunogenic ECLs of two newly discovered OMPs, while advancing the utility of the rabbit model for surveying the entire Tp OMPeome for promising OMP vaccinogens. This work represents a major advancement toward characterizing potentially protective OMP ECLs and future vaccine studies. Additionally, this strategy could be applied to OMPs of nonspirochetal bacterial pathogens.
Databáze:	MEDLINE
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