Bacterial superglue generates a full-length circumsporozoite protein virus-like particle vaccine capable of inducing high and durable antibody responses

Abstract

BackgroundMalaria, caused by Plasmodium falciparum, continues to have a devastating impact on global health, emphasizing the great need for a malaria vaccine. The circumsporozoite protein (CSP) is an attractive target for a malaria vaccine, and forms a major component of RTS,S, the most clinically advanced malaria vaccine. The clinical efficacy of RTS,S has been moderate, yet has demonstrated the viability of a CSP-based malaria vaccine. In this study, a vaccine comprised of the full-length CSP antigen presented on a virus-like particle (VLP) is produced using a split-intein conjugation system (SpyTag/SpyCatcher) and the immunogenicity is tested in mice.MethodsFull-length 3d7 CSP protein was genetically fused at the C-terminus to SpyCatcher. The CSP-SpyCatcher antigen was then covalently attached (via the SpyTag/SpyCatcher interaction) to Acinetobacter phage AP205 VLPs which were modified to display one SpyTag per VLP subunit. To evaluate the VLP-display effect, the immunogenicity of the VLP vaccine was tested in mice and compared to a control vaccine containing AP205 VLPs plus unconjugated CSP.ResultsFull-length CSP was conjugated at high density (an average of 112 CSP molecules per VLP) to AP205 SpyTag-VLPs. Vaccination of mice with the CSP Spy-VLP vaccine resulted in significantly increased antibody titres over a course of 7 months as compared to the control group (2.6-fold higher at 7 months after immunization). Furthermore, the CSP Spy-VLP vaccine appears to stimulate production of IgG2a antibodies, which has been linked with a more efficient clearing of intracellular parasite infection.ConclusionThis study demonstrates that the high-density display of CSP on SpyTag-VLPs, significantly increases the level and quality of the vaccine-induced humoral response, compared to a control vaccine consisting of soluble CSP plus AP205 VLPs. The SpyTag-VLP platform utilized in this study constitutes a versatile and rapid method to develop highly immunogenic vaccines. It might serve as a generic tool for the cost-effective development of effective VLP-vaccines, e.g., against malaria.

Development of target‐tunable P22 VLP‐based delivery nanoplatforms using bacterial superglue

“…We also demonstrated that those conjugates exhibited a range of different functions (Bae et al, ; Choi et al, ; Moon et al, ). The ST/SC protein ligation system has been applied for displaying various antigenic proteins and targeting ligands on VLPs and their effective immune response inductions and cell‐specific gene delivery were successfully demonstrated (Brune et al, , ; Bruun, Andersson, Draper, & Howarth, ; Janitzek et al, ; Kasa, Raneni, Chamoun‐Emanuelli, Wright, & Chen, ; Ke et al, ; Leneghan et al, ; Singh et al, ; Thrane et al, ).…”

Advantages and Prospects of Tag/Catcher Mediated Antigen Display on Capsid-Like Particle-Based Vaccines

“…Importantly, when using such modular approaches, the resultant epitope display is directly dependent on the applied conjugation method, as well as the specific surface geometry of the employed CLP backbone. In addition, these technologies allow for separate recombinant production of antigens in various expression systems, ensuring high quality and correct protein processing before CLP conjugation [39][40][41][42]. The different conjugation systems used for modular CLP vaccine development is described in detail elsewhere [43].…”

Capsid-like particles decorated with the SARS2-CoV-2 receptor-binding domain elicit strong virus neutralization activity

“…The RBD-Catcher coupling efficiency was calculated as percentage conjugation (i.e. number of bound antigens divided by the total available binding sites (=180) per CLP) by densitometric analysis of on the SDS-PAGE gel, using ImagequantTL (as previously described 67 . In parallel, RBDc-CLP was purified by density gradient ultracentrifugation by adding the RBDc-CLP onto an Optiprep™ step gradient (23, 29 and 35%) (Sigma-Aldrich) followed by centrifugation for 3.30h at 47800rpm, as previously described26.…”