Here, we present a protocol to generate a proof-of-principle divalent adenovirus type 5 (Ad5) vector Ad5/H5-HVR1-KWAS-HVR5-His6 by utilizing the Antigen Capsid-Incorporation strategy. This vector was demonstrated to exhibit qualitative fitness, the capability to escape Ad5-positive sera in vitro, and the antigenicity as well as immunogenicity to the incorporated antigens.
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Method Article
Utilizing the Antigen Capsid-Incorporation Strategy for the Development of Adenovirus Serotype 5-Vectored Vaccine Approaches
In This Article
Summary
Abstract
Adenovirus serotype 5 (Ad5) has been extensively modified with traditional transgene methods for the vaccine development. The reduced efficacies of these traditionally modified Ad5 vectors in clinical trials could be primarily correlated with Ad5 pre-existing immunity (PEI) among the majority of the population. To promote Ad5-vectored vaccine development by solving the concern of Ad5 PEI, the innovative Antigen Capsid-Incorporation strategy has been employed. By merit of this strategy, Ad5-vectored we first constructed the hexon shuttle plasmid HVR1-KWAS-HVR5-His6/pH5S by subcloning the hypervariable region (HVR) 1 of hexon into a previously constructed shuttle plasmid HVR5-His6/pH5S, which had His6 tag incorporated into the HVR5. This HVR1 DNA fragment containing a HIV epitope ELDKWAS was synthesized. HVR1-KWAS-HVR5-His6/pH5S was then linearized and co-transformed with linearized backbone plasmid pAd5/∆H5 (GL) , for homologous recombination. This recombined plasmid pAd5/H5-HVR1-KWAS-HVR5-His6 was transfected into cells to generate the viral vector Ad5/H5-HVR1-KWAS-HVR5-His6. This vector was validated to have qualitative fitness indicated by viral physical titer (VP/ml), infectious titer (IP/ml) and corresponding VP/IP ratio. Both the HIV epitope and His6 tag were surface-exposed on the Ad5 capsid, and retained epitope-specific antigenicity of their own. A neutralization assay indicated the ability of this divalent vector to circumvent neutralization by Ad5-positive sera in vitro. Mice immunization demonstrated the generation of robust humoral immunity specific to the HIV epitope and His6. This proof-of-principle study suggested that the protocol associated with the Antigen Capsid-Incorporation strategy could be feasibly utilized for the generation of Ad5-vectored vaccines by modifying different capsid proteins. This protocol could even be further modified for the generation of rare-serotype adenovirus-vectored vaccines.
Introduction
Human adenovirus (Ad) is a medium-sized, non-enveloped virus with an icosahedral nucleocapsid containing a double stranded DNA genome. Ad belongs to the Adenoviridae family, with a classification into seven groups (A through G). Each group contains virus of different serotypes. Of which, adenovirus serotype 5 (Ad5) from group C has been the most extensively studied and the most widely applied for vectored approaches like gene therapy and vaccinations.
The traditional transgene strategy has been developed and applied for Ad5 modifications, which is characterized by the displacement of the virus early genes with a gene-of-interest, and the fo....
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Protocol
The University of Alabama at Birmingham Institutional Animal Use and Care Committee approved the use of mice as described herein under the approved protocol number 101109272.
1. Genetic Construction of a Modified Plasmid pAd5/H5-HVR1-KWAS-HVR5-His 6 with the Antigen Capsid-Incorporation Strategy
- Construction of the shuttle plasmid HVR1-KWAS-HVR5-His6/pH5S
- Order a plasmid containing the synthesized DNA sequence HVR1-KWAS between the restriction enzyme sites AgeI to AccI of hexon5 gene.
- Digest 6 µg of the synthesized fragment (HVR1-KWAS) with the enzymes AgeI (6 units) and AccI (6 ....
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Results
The Antigen Capsid-Incorporation strategy (Figure 1A) was utilized to generate the divalent Ad5 viral vector Ad5/H5-HVR1-KWAS-HVR5-His6. Firstly, the shuttle plasmid HVR1-KWAS-HVR5-His6/pH5S was constructed by subcloning HVR1-KWAS fragment into the previous constructed shuttle plasmid HVR5-His6/pH5S17. Secondly, the plasmid pAd5/H5-HVR1-KWAS-HVR5-His614 was constructed by a homologous recombination between the fragment of “EcoRI-HVR1-KWAS-.......
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Discussion
The application of the traditional transgene strategy on Ad5 modification for the development of vaccines has been diminished primarily due to the bottleneck associated with the Ad5 PEI4,6. This bottleneck can be partially diminished by application of the alternative Antigen Capsid-Incorporation strategy (Figure 1A), since this strategy can evade neutralization by Ad5 NAbs by replacing neutralizing epitopes of Ad5 with antigens-of-interest, and facilitate the generation of robust immunity to t.......
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Disclosures
The authors have nothing to disclose.
Acknowledgements
This work was supported in part by National Institutes of Health grants 5T32AI7493-20 and 5R01AI089337-03. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| 1x DPBS | Thermo Scientific | SH30256.01 | for cell spliting |
| 10x DPBS | Thermo Scientific | SH30378.02 | for dialysis buffer preparation |
| glycerol | SIGMA | G5516-1L | for dialysis buffer preparation |
| SDS | BIO-RAD | 161-0301 | for virus lysis buffer preparation |
| Fetal Bovine Serum (FBS) | Thermo Scientific | SH30910.03 | component of culture medium |
| 100x Non-Essential Amino Acids | Thermo Scientific | SH30238.01 | component of culture medium |
| 200 mM L-glutamine | Cellgro | 25-005-CI | component of culture medium |
| penicillin/streptomycin solution | Cellgro | 30-002-CI | component of culture medium |
| DMEM with high glucose | Thermo Scientific | SH30081.01 | for HEK293 cell culture |
| Minimum Essential Medium Eagle | SIGMA | M5650 | for HeLa cell culture |
| phenol:chloroform:isoamyl alcohol | SIGMA | P3803-100ML | for large size of DNA purification |
| cesium chloride | Research Products International Corp. | C68050 | for virus purificiation |
| HEPES | Cellgro | 25-060-CI | for CsCl solution preparation |
| HEK293 | ATCC | 51-0036 | for virus rescue and upscale |
| HeLa | ATCC | CCL-2 | for neutralization assay |
| T-25 flask | Thermo Scientific | 156367 | for cell culture |
| T-75 flask | CORNING | 430641 | for cell culture |
| T-175 flask | Thermo Scientific | 159910 | for cell culture |
| Ultracentrifuge | BECKMAN | NA | for virus purification |
| Ultracentrifuge tube | BECKMAN | 344059 | for virus purification |
| dialysis cassette | Thermo Scientific | 66380 | for virus dialysis |
| ELISA plate | Thermo Scientific | 442404 | for ELISA |
| human anti-gp41 (2F5) mAb | NIH AIDS Reagent Program | 1475 | for immunological assays |
| mouse anti-His tag mAb | GenScript | A00186 | for immunological assays |
| SOC medium | CORNING | 46-003-CR | for transformation |
| PCR master mix solution | QIAGEN | 201445 | for PCR |
| Animal lancet (point length at 5 mm) | MEDIpoint | for mice bleeding | |
| Biophotometer | Eppendorf | for virus physical titer titration |
References
- Cheng, S. M., et al. Coexpression of the simian immunodeficiency virus Env and Rev proteins by a recombinant human adenovirus host range mutant. Journal of virology. 66, 6721-6727 (1992).
- Matthews, Q. L., et al.
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