Hepatitis E virus truncated capsid protein as a potential carrier of exogenous antigens for the development of chimeric virus-like particle vaccines

Abstract Background: Virus like particle (VLP), a multiprotein structure which is assembled automatically, can stimulate robust immune responses due to an appropriate size, repetitive epitopes, and a structure similar to native virions. Utilizing VLPs as vaccine carriers to present exogenous antigens is a promising and challenging field in vaccine design. Hence, this study aims to investigate the potential of Hepatitis E virus (HEV) truncated capsid protein as a VLP carrier presenting foreign antigens in vaccine design.Results: S and M domains of HEV ORF2 protein (aa112-455) were selected as an optimal carrier (CaSM). The exogenous antigen Seq8 containing three immunogenic domains from three different foot-and-mouth disease virus (FMDV) strains was linked to the C-terminal of CaSM to construct a chimeric VLP vaccine candidate (CaSM-Seq8). Morphological analysis showed that CaSM-Seq8 self-assembled into VLPs with a diameter of approximately 26 nm, similar to the VLPs of CaSM alone but smaller than native HEV virions. Further, the thermal stability and the proteolysis resistance of Seq8 were enhanced when carried by CaSM. The antigenicity analysis revealed a more robust reactivity against anti-FMDV specific antibodies when Seq8 was presented on the CaSM particles. Upon injection into mice, anti-FMDV IgGs induced by CaSM-Seq8 appeared earlier, increased faster, and maintained higher levels for a longer time than those induced by Seq8 antigen alone or a commercial inactivated FMDV vaccine.Conclusions: This study demonstrates the potential of the HEV truncated capsid protein VLPs as a presenting-platform of exogenous antigens in vaccine design and promising preliminary results on chimeric VLP vaccine against foot-and-mouth disease.

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Generation of Antibodies against Foot-and-Mouth-Disease Virus Capsid Protein VP4 Using Hepatitis B Core VLPs as a Scaffold

Life ◽

10.3390/life11040338 ◽

2021 ◽

Vol 11 (4) ◽

pp. 338

Author(s):

Jessica Swanson ◽

Rennos Fragkoudis ◽

Philippa C. Hawes ◽

Joseph Newman ◽

Alison Burman ◽

...

Keyword(s):

Amino Acids ◽

Hepatitis B ◽

Capsid Protein ◽

Disease Virus ◽

Foot And Mouth Disease ◽

Mouth Disease ◽

Specific Antibodies ◽

Mouth Disease Virus ◽

N Terminus ◽

Foot And Mouth

The picornavirus foot-and-mouth disease virus (FMDV) is the causative agent of the economically important disease of livestock, foot-and-mouth disease (FMD). VP4 is a highly conserved capsid protein, which is important during virus entry. Previous published work has shown that antibodies targeting the N-terminus of VP4 of the picornavirus human rhinovirus are broadly neutralising. In addition, previous studies showed that immunisation with the N-terminal 20 amino acids of enterovirus A71 VP4 displayed on the hepatitis B core (HBc) virus-like particles (VLP) can induce cross-genotype neutralisation. To investigate if a similar neutralising response against FMDV VP4 could be generated, HBc VLPs displaying the N-terminus of FMDV VP4 were designed. The N-terminal 15 amino acids of FMDV VP4 was inserted into the major immunodominant region. HBc VLPs were also decorated with peptides of the N-terminus of FMDV VP4 attached using a HBc-spike binding tag. Both types of VLPs were used to immunise mice and the resulting serum was investigated for VP4-specific antibodies. The VLP with VP4 inserted into the spike, induced VP4-specific antibodies, however the VLPs with peptides attached to the spikes did not. The VP4-specific antibodies could recognise native FMDV, but virus neutralisation was not demonstrated. This work shows that the HBc VLP presents a useful tool for the presentation of FMDV capsid epitopes.

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An Engineered Maturation Cleavage Provides a Recombinant Mimic of Foot-and-Mouth Disease Virus Capsid Assembly-Disassembly

Life ◽

10.3390/life11060500 ◽

2021 ◽

Vol 11 (6) ◽

pp. 500

Author(s):

Joseph Newman ◽

David J. Rowlands ◽

Tobias J. Tuthill

Keyword(s):

Capsid Protein ◽

Disease Virus ◽

Foot And Mouth Disease ◽

Mouth Disease ◽

Virion Assembly ◽

Capsid Precursor ◽

Mouth Disease Virus ◽

Foot And Mouth ◽

Assembly Intermediate ◽

Capsid Stability

Picornavirus capsids are assembled from 60 copies of a capsid precursor via a pentameric assembly intermediate or ‘pentamer’. Upon completion of virion assembly, a maturation event induces a final cleavage of the capsid precursor to create the capsid protein VP4, which is essential for capsid stability and entry into new cells. For the picornavirus foot-and-mouth disease virus (FMDV), intact capsids are temperature and acid-labile and can disassemble into pentamers. During disassembly, capsid protein VP4 is lost, presumably altering the structure and properties of the resulting pentamers. The purpose of this study was to compare the characteristics of recombinant “assembly” and “disassembly” pentamers. We generated recombinant versions of these different pentamers containing an engineered cleavage site to mimic the maturation cleavage. We compared the sedimentation and antigenic characteristics of these pentamers using sucrose density gradients and reactivity with an antibody panel. Pentamers mimicking the assembly pathway sedimented faster than those on the disassembly pathway suggesting that for FMDV, in common with other picornaviruses, assembly pentamers sediment at 14S whereas only pentamers on the disassembly pathway sediment at 12S. The reactivity with anti-VP4 antibodies was reduced for the 12S pentamers, consistent with the predicted loss of VP4. Reactivity with other antibodies was similar for both pentamers suggesting that major antigenic features may be preserved between the VP4 containing assembly pentamers and the disassembly pentamers lacking VP4.

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