Bioengineered bacteria-derived outer membrane vesicles as a versatile antigen display platform for tumor vaccination via Plug-and-Display technology

Abstract

An effective tumor vaccine vector that can rapidly display neoantigens is urgently needed. Outer membrane vesicles (OMVs) can strongly activate the innate immune system and are qualified as immunoadjuvants. Here, we describe a versatile OMV-based vaccine platform to elicit a specific anti-tumor immune response via specifically presenting antigens onto OMV surface. We first display tumor antigens on the OMVs surface by fusing with ClyA protein, and then simplify the antigen display process by employing a Plug-and-Display system comprising the tag/catcher protein pairs. OMVs decorated with different protein catchers can simultaneously display multiple, distinct tumor antigens to elicit a synergistic antitumour immune response. In addition, the bioengineered OMVs loaded with different tumor antigens can abrogate lung melanoma metastasis and inhibit subcutaneous colorectal cancer growth. The ability of the bioengineered OMV-based platform to rapidly and simultaneously display antigens may facilitate the development of these agents for personalized tumour vaccines.

A modular platform for on-demand vaccine self-assembly enabled by decoration of bacterial outer membrane vesicles with biotinylated antigens

“…As we showed here, SNARE-OMVs can be readily adorned with virtually any antigen that is amenable to biotinylation including globular and membrane proteins, glycans and glycoconjugates, haptens, lipids, and short peptides. The ability to precisely and homogenously load OMVs with a molecularly diverse array of subunit antigens differentiates the AddVax method from previous covalent conjugation strategies that are largely restricted to protein and peptide antigens (31,33,34). Moreover, our dock-and-display approach side-steps many of the challenges associated with display on OMVs using conventional genetic fusion and cellular expression technology, thereby opening the door to important vaccine subunit antigens such as malarial Pfs25 and Chlamydia Cm-MOMP that are refractory to soluble expression and outer membrane localization in E. coli (45,(50)(51)(52)(53).…”

“…To this end, two groups recently demonstrated specific bioconjugation on OMVs by adapting a "plug-and-display" approach that had previously been developed for decorating virus-like particles with protein and peptide antigens (32). This approach involved the use of the SpyTag/SpyCatcher protein ligation system to covalently attach purified SpyTag-antigen (or SpyCatcher-antigen) fusion proteins onto cognate SpyCatcher-scaffold (or SpyTag-scaffold) fusions that were expressed on the surface of OMVs (33,34). While this enabled loading of exogenous antigens on OMVs, with one report even demonstrating specific anti-tumor immune responses (33), the protein ligation strategy is limited to proteinaceous antigens that are compatible with isopeptide bond formation.…”

Development of Extracellular Vesicle Therapeutics: Challenges, Considerations, and Opportunities

“…Previously, the ground-breaking application of EVs in anti-tumor immunotherapy ( Zitvogel et al, 1998 ) led to two clinical trials where EVs activated patient immune response against tumor antigens ( Escudier et al, 2005 ; Morse et al, 2005 ). Since then, refinements in EV production and modification have led to successful reduction in tumor size in various pre-clinical models ( Lee et al, 2012 ; Mahaweni et al, 2013 ; Rao et al, 2016 ; Cheng et al, 2021 ) and additional clinical trials exploiting their immunomodulatory capabilities to target various cancer types (NCT01550523, NCT01159288, and NCT02507583) ( Besse et al, 2016 ; Andrews et al, 2021 ). The use of EVs as antigen vehicles is an approach still under development ( Cheng et al, 2021 ; Hu S. et al, 2021 ), but does represent the most successful translated application.…”

“…Since then, refinements in EV production and modification have led to successful reduction in tumor size in various pre-clinical models ( Lee et al, 2012 ; Mahaweni et al, 2013 ; Rao et al, 2016 ; Cheng et al, 2021 ) and additional clinical trials exploiting their immunomodulatory capabilities to target various cancer types (NCT01550523, NCT01159288, and NCT02507583) ( Besse et al, 2016 ; Andrews et al, 2021 ). The use of EVs as antigen vehicles is an approach still under development ( Cheng et al, 2021 ; Hu S. et al, 2021 ), but does represent the most successful translated application. The FDA approved Bexsero bacterial outer membrane vesicle (OMV)-containing meningococcal vaccine is administered to protect against meningococcal group B ( Gorringe and Pajon, 2012 ).…”

“…Accumulating evidence indicates that other naturally-derived EV source, including plant-based (NCT01668849, NCT01294072) ( Dad et al, 2021 ) and bovine-milk-derived EVs ( Grossen et al, 2021 ) may be sustainable alternatives for large-scale utility of engineered EVs. Bacterial EVs from non-pathogenic or probiotic bacterial source may also be harnessed as potential EV-based delivery carriers for anti-inflammatory function ( Kuhn et al, 2020 ), with further advantages in their versatility in being readily functionalized ( Shehata et al, 2019 ; Cheng et al, 2021 ) and their scalable production ( Gujrati et al, 2014 ; Cheng et al, 2021 ).…”