Immunogenicity and Vaccine Efficacy Boosted by Engineering Human Heavy Chain Ferritin and Chimeric Hepatitis B Virus Core Nanoparticles

Abstract

Human heavy-chain ferritin (HFn) and hepatitis B virus core (HBc) are both nanoparticle proteins presenting a well-oriented architecture with constant size and shape, which can be engineered to carry epitopes on the surface of the nanoparticle protein cage, enabling vaccine design. This study aims to investigate the immunogenicity differences between engineered HFn and chimeric HBc bearing the same epitope. As a proof of concept, the model epitope Epstein−Barr nuclear antigen 1 (EBNA1) is inserted at the N-terminus of the HFn and HBc subunit to produce two vaccine candidates named EBNA1−HFn (E1F1) and EBNA1−HBc (E1H1), respectively. From in vivo immunogenicity studies, E1H1 demonstrates the capability to prompt significant humoral and cell-mediated immune responses in adjuvant-free formulation. When formulated with the aluminum hydroxide adjuvant, E1H1 produces approximately 5× higher titer and 2× stronger proliferation index (PI) than E1F1. These results confirm that the HBc carrier induces a stronger humoral immune response than HFn. On the other hand, from lymphocyte activation experiments, E1F1 induces a stronger cell-mediated immune response indicated by 5× more CD8 + T cells and 2× more effector memory T cells in the E1F1 group versus the E1H1 group. Through this study, HFn and HBc are shown to be potentially effective vaccine carrier nanoparticles having subtly different immunological responses. KEYWORDS: protein-based vaccine molecule design, hepatitis B virus core, virus like particles, human ferritin heavy chain, Epstein−Barr nuclear antigen 1

Biological Nanoparticles in Vaccine Development

“…Protein nanocages, such as those derived from ferritin, also show promise as novel vaccine platforms. The repetitive surface properties of these compounds, their size, as well as their ease of modification, through either genetic or chemical means, makes them a very interesting platform capable of eliciting strong memory responses, and protection against viral challenge, even without the presence of adjuvant ( Qi et al, 2018 ; Wei et al, 2020 ; Qu et al, 2021b ).…”

“…Genetic modification of ferritin not only permits antigenic display, but also allows for the introduction of mutations that may improve functionality, such as addition of a cysteine group to the exterior to allow for conjugation of adjuvants via click chemistry ( Kamp et al, 2020 ). Due to its versatility, ferritin has been engineered as a vaccine platform to display antigens from various pathogens, including Borrelia burgdorferi ( Kamp et al, 2020 ), influenza ( Kanekiyo et al, 2013 ; Yassine et al, 2015 ; Qi et al, 2018 ; Wei et al, 2020 ), Epstein-Barr virus ( Kanekiyo et al, 2015 ; Qu et al, 2021b , 2021a ), hepatitis B ( Wang W. et al, 2020 ), rotavirus ( Li et al, 2019 ), and, most recently, SARS-Cov-2 ( Joyce et al, 2021 ; Kalathiya et al, 2021 ; Kang et al, 2021 ; King et al, 2021 ; Wuertz et al, 2021 ).…”

Ferritin-based nanomedicine for disease treatment

“…Unfortunately, there is still no vaccine available. Ferritin-based EBV vaccines brought new opportunities to prevent this fatal illness [ 182 , 193 – 195 ]. Kanekiyo et al.…”

Chimeric Hepatitis B core virus-like particles harboring SARS-CoV2 epitope elicit a humoral immune response in mice

“…Due to their particular structure and repetitive surface patterns, they can promisingly display immunogenic epitopes on their surface and elicit specific powerful immune responses [ 10 ]. Different chimeric VLP-based vaccines against animal and human infectious diseases have been investigated in the last few years [ 11 – 15 ]. One of the most potent VLP candidates for packaging and displaying foreign epitopes and triggering particular immunogenicity is the hepatitis B core (HBc) VLP [ 16 , 17 ].…”