Bacterial outer membrane vesicles engineered with lipidated antigens as a platform for Staphylococcus aureus vaccine

Abstract

Bacterial outer membrane vesicles (OMVs) represent an interesting vaccine platform for their built-in adjuvanticity and simplicity of production process. Moreover, OMVs can be decorated with foreign antigens using different synthetic biology approaches. However, the optimal OMV engineering strategy, which should guarantee the OMV compartmentalization of most heterologous antigens in quantities high enough to elicit protective immune responses, remains to be validated. In this work we exploited the lipoprotein transport pathway to engineer OMVs with foreign proteins. Using 5 Staphylococcus aureus protective antigens expressed in Escherichia coli as fusions to a lipoprotein leader sequence, we demonstrated that all 5 antigens accumulated in the vesicular compartment at a concentration ranging from 5 to 20% of total OMV proteins, suggesting that antigen lipidation could be a universal approach for OMV manipulation. Engineered OMVs elicited high, saturating antigen-specific antibody titers when administered to mice in quantities as low as 0.2 μg/dose. Moreover, the expression of lipidated antigens in E. coli BL21(DE3)ΔompAΔmsbBΔpagP was shown to affect the lipopolysaccharide structure, with the result that the TLR4 agonist activity of OMVs was markedly reduced. These results, together with the potent protective activity of engineered OMVs observed in mice challenged with S. aureus Newman strain, makes the 5-combo-OMVs a promising vaccine candidate to be tested in clinics.

PE_PGRS33, an Important Virulence Factor of Mycobacterium tuberculosis and Potential Target of Host Humoral Immune Response

“…Inclusion of recombinant PE_PGRS33 purified under native conditions in already available vaccine platforms, such as BCG or new vaccines against TB, may be a strategy that can be useful to pursue [ 80 ]. Immunization with BCG strains overexpressing PE_PGRS33 or with extracellular membrane vesicles [ 108 , 109 ] enriched in PE_PGRS33 may serve to elicit antibody responses against protein domains presenting the appropriate structure to elicit functionally active antibodies capable of neutralizing PE_PGRS33 and/or of opsonizing Mtb . The fact that Mtb expresses more than 50 PE_PGRS proteins on the mycobacterial surface, with structural features similar to those of PE_PGRS33, and that these proteins play unique roles in the Mtb infection process and immunopathogenesis of TB, underscores the potential impact that a vaccination strategy targeting PE_PGRS proteins may have in the control of TB.…”

Helicobacter pylori-Derived Outer Membrane Vesicles (OMVs): Role in Bacterial Pathogenesis?

“…Their immunogenicity, as well as their similarity to their bacterial mother cells, might however make them of particular interest for vaccine development [ 61 ]. In fact, a Neisseria meningitidis OMV-containing vaccine (Bexsero) was approved in 2013 for meningitis B by the FDA and EMA, and further OMV based vaccines are currently in development for other pathogenic bacteria [ 17 , 98 , 99 , 100 ]. Vaccine development for H. pylori infection has historically been challenging.…”

Proteome‐minimized outer membrane vesicles from Escherichia coli as a generalized vaccine platform

“…Plasmids encoding FhuD2, SpA KKAA , Csa1, Hla H35L , FhuD2‐mFAT1 and Nm‐NHBA were already described (Fantappiè et al., 2017; Grandi et al., 2018; Irene et al., 2019). For the construction of plasmids encoding ClfA Y338A , FhuD2‐Bp, FhuD2‐OVA and FhuD2‐hFAT1, the PIPE‐PCR method was used (Klock & Lesley, 2009).…”

“…OMVs are becoming an attractive vaccine platform for their excellent adjuvanticity (Chen et al., 2010; Ellis & Kuehn, 2010), the possibility of decorating them with heterologous antigens (Gerritzen et al., 2017; Irene et al., 2019; Kesty & Kuehn, 2004), and the simplicity of their production and purification process (Berlanda Scorza et al., 2012). Indeed, OMV‐based vaccines have already reached the market (Ladhani et al., 2016; Serruto et al., 2012), while others are in advanced clinical phases (Gerke et al., 2015; Rossi et al., 2016).…”