Bacterial superglue enables easy development of efficient virus-like particle based vaccines

Abstract

BackgroundVirus-like particles (VLPs) represent a significant advance in the development of subunit vaccines, combining high safety and efficacy. Their particulate nature and dense repetitive subunit organization makes them ideal scaffolds for display of vaccine antigens. Traditional approaches for VLP-based antigen display require labor-intensive trial-and-error optimization, and often fail to generate dense antigen display. Here we utilize the split-intein (SpyTag/SpyCatcher) conjugation system to generate stable isopeptide bound antigen-VLP complexes by simply mixing of the antigen and VLP components.ResultsGenetic fusion of SpyTag or SpyCatcher to the N-terminus and/or C-terminus of the Acinetobacter phage AP205 capsid protein resulted in formation of stable, nonaggregated VLPs expressing one SpyCatcher, one SpyTag or two SpyTags per capsid protein. Mixing of spy-VLPs with eleven different vaccine antigens fused to SpyCatcher or SpyTag resulted in formation of antigen-VLP complexes with coupling efficiencies (% occupancy of total VLP binding sites) ranging from 22–88 %. In mice, spy-VLP vaccines presenting the malaria proteins Pfs25 or VAR2CSA markedly increased antibody titer, affinity, longevity and functional efficacy compared to corresponding vaccines employing monomeric proteins. The spy-VLP vaccines also effectively broke B cell self-tolerance and induced potent and durable antibody responses upon vaccination with cancer or allergy-associated self-antigens (PD-L1, CTLA-4 and IL-5).ConclusionsThe spy-VLP system constitutes a versatile and rapid method to develop highly immunogenic VLP-based vaccines. Our data provide proof-of-concept for the technology’s ability to present complex vaccine antigens to the immune system and elicit robust functional antibody responses as well as to efficiently break B cell self-tolerance. The spy-VLP-system may serve as a generic tool for the cost-effective development of effective VLP-vaccines against both infectious- and non-communicable diseases and could facilitate rapid and unbiased screening of vaccine candidate antigens.Electronic supplementary materialThe online version of this article (doi:10.1186/s12951-016-0181-1) contains supplementary material, which is available to authorized users.

A VAR2CSA:CSP conjugate capable of inducing dual specificity antibody responses

“…The DBL1x-DBL2x-ID2a region of VAR2CSA antigen from FCR3 genotype (Gene ID: 814364) was designed with C-terminally linked hexa-histidine purification tag (HIS), as well as SpyTag at the N-terminal 15 . A flexible linker made of serine/glycine was inserted between SpyTag and DBL1x-DBL2x-ID2a antigen.…”

“…BamHI and NotI restriction site was introduced on SpyTag-DBL1x-DBL2x-ID2a-HIS gene specifically at N-and C-terminus, respectively. The sequences were codon optimized and synthesized by GeneArt® Life Technologies (Germany), before cloning and expression in baculovirus transfected Spodoptera frugiperda (Sf9) insect cells as described previously by 15,16 . For recombinant expression, Sf9 cells were African Health Sciences Vol 17 Issue 2, June, 2017co-transfected with linear BakPak viral DNA (BD Biosciences) and pAcGP67A/SpyTag-DBL1x-DBL2x-ID2a-HIS plasmid DNA using Lipofectamine 2000 Reagent (Invitrogen, 11668-019).…”

“…The study serves as a proof of concept for simultaneous induction of antibodies against DBL1x-DBL2x-ID2a and CSP as a combined antigen. Future development of the vaccine would combine dual stage antigen linkage with VLP-display 15 .…”

“…HIS-CSP-SpyCatcher gene was later modified to contain the BamHI and NotI restriction site at Nand C-terminus, respectively, and codon-optimized for synthesis (GeneArt® Life Technologies, Germany). The gene was subsequently expressed in Trichoplusia ni insect cells, as described previously by 15,18 .…”

Virus Like Nanoparticles: Display Matters

“…Very recently, Thrane and colleagues published an article where they exploited a split inteine SpyTag/ SpyCatcher conjugation system to develop antigencomplexed VLPs (Thrane et al, 2016). This system is based on a protein domain, CnaB2 from the fibronectin adhesion protein (FbaB) of bacterium Staphylococcus pyogenes (Spy).…”