Comparative immunogenicity of bacterially expressed soluble trimers and nanoparticle displayed influenza hemagglutinin stem immunogens

Abstract

Influenza is a highly contagious virus, belonging to the family Orthomyxovirus that causes acute febrile respiratory illness which may even be fatal in some cases. Self-assembling protein nanoparticles have been used to display several copies of an immunogen, thus enhancing B cell and T cell immune responses through avidity effects. Using an iterative structure-guided approach, we successfully displayed twelve copies of a previously designed influenza stem domain immunogen pH1HA10 on the ferritin like protein, Msdps2. The nanoparticle fusion immunogen was well folded and bound to the influenza stem directed broadly neutralizing antibody CR6261 with very high affinity. An 8.5 angstrom Cryo-EM map of the nanoparticle fusion protein confirmed the successful design of the nanoparticle fusion immunogen. Preliminary mice immunization studies with the nanoparticle fusion construct revealed that the Msdps2-pH1HA10 fusion construct is immunogenic, this will be further evaluated in challenge studies.

Immunogenicity and protective efficacy of a highly thermotolerant, trimeric SARS-CoV-2 receptor binding domain derivative

“…A dodecameric selfassembling nanoparticle (MsDPS2) from Mycobacterium smegmatis was fused to SpyTag 45,46 by a 15 residue linker to aid in the complexation of nanoparticle with mRBD-SpyCatcher (Figure 1b). We have successfully employed the MsDPS2 nanoparticle to display trimeric influenza stem immunogens 57 . and negligible dissociation (Figure 1m, Supporting Figure S2).…”

Heterologous Prime-Boost with Immunologically Orthogonal Protein Nanoparticles for Peptide Immunofocusing

“…4,[8][9] Since their discovery in the 1990s, encapsulin scaffolds have been derivatized to serve a variety of biotechnology, therapeutic, and materials functions, including as photo-switchable imaging, 10 catalysis, [11][12][13] cellular imaging, [14][15][16] targeted drug delivery, [17][18] toxin remediation, 19 and vaccination. [20][21][22][23][24] In modern immunization strategies, the selection of antigenic peptide epitopes from a given pathogen's protein repertoire is often key to developing successful antibody and T cell responses against infectious pathogens. However, vaccination with such peptides alone usually fails to promote sufficiently robust responses, [25][26] requiring the use of carrier proteins for conjugate vaccines, a role for which protein nanoparticles are well suited by virtue of their efficient lymphatic trafficking, engagement of immune cell receptors, uptake, processing, and induction of cellular signaling.…”

“…20 The former particle was administered to mice with Freund's adjuvant and the latter with the Sigma adjuvant system. Encapsulins from Myxococcus xanthus were recently engineered to display receptor binding domains form SARS-CoV-2 virus 24 or influenza hemagglutinin, 23 and were tested immunologically with a squalene-in-water emulsion adjuvant. Lastly, only one report has appeared of an encapsulin-peptide conjugate vaccine, in this case using the prototypical Ova2 peptide (SIINFEKL) antigen attached by chemical means to T. maritima encapsulins and administered with poly (I:C) adjuvant.…”