Journal: Mol Ther Adv / Year: 2026 Title: Immune shielding of viral vectors via capsid engineering with genetically encoded zwitterionic peptides. Authors: Shao-Chia Lu / Olivia X Ma / Alex A Anwar / Dimitrije Ratkov / Janarjan Bhandari / Daniel J Montiel-Garcia / Michael J Hansen / Mary E Barry / Vijay S Reddy / Michael A Barry / Abstract: Pre-existing neutralizing antibodies (NAbs) and blood proteins can rapidly inactivate therapeutic viral vectors and trigger immune toxicities in patients. To overcome these challenges, we engineered ...Pre-existing neutralizing antibodies (NAbs) and blood proteins can rapidly inactivate therapeutic viral vectors and trigger immune toxicities in patients. To overcome these challenges, we engineered the surfaces of adenovirus (Ad) by incorporating genetically encoded "protective shields" to reduce the recognition by host factors. AlphaFold3 modeling showed that inserting a structured biotin acceptor peptide (BAP) into hypervariable region 5 (HVR5) of the viral capsid protein hexon produced a rigid surface protrusion, whereas inserting a disordered, zwitterionic glutamic acid-lysine (EK) peptide formed a flexible canopy over the hexon. Although inserting EK peptides into the capsid impaired viral entry and intracellular trafficking that led to reduced viral transduction and , this modification decreased binding by coagulation factor X (FX) and complement C3. Importantly, the EK peptide-modified Ad also evaded polyclonal anti-Ad NAbs without the need to change all HVRs. The shielding efficiency of EK peptides was affected by their composition and length. Cryoelectron microscopy (cryo-EM) and neutralization assays further revealed that NAbs primarily target HVR1, a region potentially masked by EK peptides inserted in HVR5. These findings demonstrate an alternative capsid engineering approach using genetically encoded peptides to enhance immune stealth of viral vectors.
History
Deposition
Jan 10, 2026
Deposition site: RCSB / Processing site: RCSB
Revision 1.0
May 27, 2026
Provider: repository / Type: Initial release
Revision 1.0
May 27, 2026
Data content type: EM metadata / Data content type: EM metadata / Provider: repository / Type: Initial release
Revision 1.0
May 27, 2026
Data content type: FSC / Data content type: FSC / Provider: repository / Type: Initial release
Revision 1.0
May 27, 2026
Data content type: Half map / Part number: 1 / Data content type: Half map / Provider: repository / Type: Initial release
Revision 1.0
May 27, 2026
Data content type: Half map / Part number: 2 / Data content type: Half map / Provider: repository / Type: Initial release
Revision 1.0
May 27, 2026
Data content type: Image / Data content type: Image / Provider: repository / Type: Initial release
Revision 1.0
May 27, 2026
Data content type: Primary map / Data content type: Primary map / Provider: repository / Type: Initial release
Mass: 111164.336 Da / Num. of mol.: 3 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Human adenovirus 6 / Production host: Human adenovirus 6
Has protein modification
N
-
Experimental details
-
Experiment
Experiment
Method: ELECTRON MICROSCOPY
EM experiment
Aggregation state: PARTICLE / 3D reconstruction method: single particle reconstruction
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Sample preparation
Component
Name: Human adenovirus 57 / Type: COMPLEX / Entity ID: all / Source: RECOMBINANT
Source (natural)
Organism: Human adenovirus 57
Source (recombinant)
Organism: Human adenovirus 6
Details of virus
Empty: NO / Enveloped: NO / Isolate: SPECIES / Type: VIRION
Natural host
Organism: Homo
Virus shell
Name: Adenovirus / Diameter: 1000 nm
Buffer solution
pH: 7.2 / Details: 20mM HEPES 7.2, 300mM NaCl
Buffer component
Conc.: 20 mM / Name: HEPES
Specimen
Conc.: 2 mg/ml / Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES
Vitrification
Cryogen name: ETHANE
-
Electron microscopy imaging
Experimental equipment
Model: Titan Krios / Image courtesy: FEI Company
Microscopy
Model: TFS KRIOS
Electron gun
Electron source: FIELD EMISSION GUN / Accelerating voltage: 300 kV / Illumination mode: FLOOD BEAM
Average exposure time: 20 sec. / Electron dose: 51 e/Å2 / Film or detector model: GATAN K3 BIOCONTINUUM (6k x 4k) / Num. of grids imaged: 3 / Num. of real images: 6515
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Processing
EM software
ID
Name
Version
Category
1
cryoSPARC
4.7
particleselection
4
cryoSPARC
3.7
CTFcorrection
7
Coot
0.9.8
modelfitting
12
cryoSPARC
4.7
3Dreconstruction
13
PHENIX
1.18.2_3874
modelrefinement
CTF correction
Type: PHASE FLIPPING AND AMPLITUDE CORRECTION
3D reconstruction
Resolution: 3.2 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 4440390 / Algorithm: FOURIER SPACE / Symmetry type: POINT
Atomic model building
Protocol: RIGID BODY FIT / Space: REAL
Atomic model building
Source name: AlphaFold / Type: in silico model
Refinement
Stereochemistry target values: REAL-SPACE (WEIGHTED MAP SUM AT ATOM CENTERS)
Refine LS restraints
Refine-ID
Type
Dev ideal
Number
ELECTRONMICROSCOPY
f_bond_d
0.006
24025
ELECTRONMICROSCOPY
f_angle_d
0.656
32656
ELECTRONMICROSCOPY
f_dihedral_angle_d
14.676
8784
ELECTRONMICROSCOPY
f_chiral_restr
0.046
3482
ELECTRONMICROSCOPY
f_plane_restr
0.005
4313
+
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