Journal: bioRxiv / Year: 2024 Title: Heterologous Prime-Boost with Immunologically Orthogonal Protein Nanoparticles for Peptide Immunofocusing. Authors: Sonia Bhattacharya / Matthew C Jenkins / Parisa Keshavarz-Joud / Alisyn Retos Bourque / Keiyana White / Amina M Alvarez Barkane / Anton V Bryksin / Carolina Hernandez / Mykhailo Kopylov / M G Finn / Abstract: Protein nanoparticles are effective platforms for antigen presentation and targeting effector immune cells in vaccine development. Encapsulins are a class of protein-based microbial nanocompartments ...Protein nanoparticles are effective platforms for antigen presentation and targeting effector immune cells in vaccine development. Encapsulins are a class of protein-based microbial nanocompartments that self-assemble into icosahedral structures with external diameters ranging from 24 to 42 nm. Encapsulins from were designed to package bacterial RNA when produced in and were shown to have immunogenic and self-adjuvanting properties enhanced by this RNA. We genetically incorporated a 20-mer peptide derived from a mutant strain of the SARS-CoV-2 receptor binding domain (RBD) into the encapsulin protomeric coat protein for presentation on the exterior surface of the particle. This immunogen elicited conformationally-relevant humoral responses to the SARS-CoV-2 RBD. Immunological recognition was enhanced when the same peptide was presented in a heterologous prime/boost vaccination strategy using the engineered encapsulin and a previously reported variant of the PP7 virus-like particle, leading to the development of a selective antibody response against a SARS-CoV-2 RBD point mutant. While generating epitope-focused antibody responses is an interplay between inherent vaccine properties and B/T cells, here we demonstrate the use of orthogonal nanoparticles to fine-tune the control of epitope focusing.
Entire : Myxococcus xanthus EncA protein modified with a his-tag and K417N...
Entire
Name: Myxococcus xanthus EncA protein modified with a his-tag and K417N(A) insertion: icosahedral T1 shell
Components
Complex: Myxococcus xanthus EncA protein modified with a his-tag and K417N(A) insertion: icosahedral T1 shell
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Supramolecule #1: Myxococcus xanthus EncA protein modified with a his-tag and K417N...
Supramolecule
Name: Myxococcus xanthus EncA protein modified with a his-tag and K417N(A) insertion: icosahedral T1 shell type: complex / ID: 1 / Parent: 0
Source (natural)
Organism: Myxococcus xanthus (bacteria)
Molecular weight
Theoretical: 2.641 MDa
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Experimental details
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Structure determination
Method
cryo EM
Processing
single particle reconstruction
Aggregation state
particle
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Sample preparation
Concentration
4.2 mg/mL
Buffer
pH: 8.5
Vitrification
Cryogen name: ETHANE / Instrument: FEI VITROBOT MARK IV / Details: 10 second wait, 1 second blot.
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Electron microscopy
Microscope
TFS GLACIOS
Image recording
Film or detector model: FEI FALCON III (4k x 4k) / Detector mode: INTEGRATING / Number grids imaged: 1 / Number real images: 2971 / Average exposure time: 1.0 sec. / Average electron dose: 50.0 e/Å2 Details: NYSBC session m23aug21f, px size 1.204 A, 25 frames
Electron beam
Acceleration voltage: 200 kV / Electron source: FIELD EMISSION GUN
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