Immunogenicity of stabilized HIV-1 Env trimers delivered by self-amplifying mRNA

Abstract

Self-amplifying mRNA (saRNA) represents a promising platform for nucleic acid delivery of vaccine immunogens. Unlike plasmid DNA, saRNA does not require entry into the nucleus of target cells for expression, having the capacity to drive higher protein expression compared to mRNA as it replicates within the cytoplasm. In this study, we examined the potential of stabilized native-like HIV-1 Envelope glycoprotein (Env) trimers to elicit immune responses when delivered by saRNA polyplexes (PLXs), assembled with linear polyethylenimine. We showed that Venezuelan equine encephalitis virus (VEEV) saRNA induces a stronger humoral immune response to the encoded transgene compared to Semliki Forest virus saRNA. Moreover, we characterized the immunogenicity of the soluble and membrane-bound ConSOSL.UFO Env design in mice and showed a faster humoral kinetic and an immunoglobulin G (IgG)2a skew using a membrane-bound design. The immune response generated by PLX VEEV saRNA encoding the membrane-bound Env was then evaluated in larger animal models including macaques, in which low doses induced high IgG responses. Our data demonstrated that the VEEV saRNA PLX nanoparticle formulation represents a suitable platform for the delivery of stabilized HIV-1 Env and has the potential to be used in a variety of vaccine regimens.

Ultra-compacted single self-amplifying RNA molecules as quintessential vaccines

“…PEI was found associated to the dissolved saRNA molecules at a stoichiometric ratio, therefore, due to its high charge density, only a low mass fraction of PEI was present within the compacted saRNA. These aqueous, single-molecule saRNA phases displayed superior activity in vaccination experiments compared to previously reported nanoparticulate PEI polyplexes (5).…”

“…Although a vast number of studies have highlighted the potential advantages of PEI, in particular in combination with saRNA for vaccination purposes (5,(22)(23)(24)(25), so far, no PEI-based product has reached commercial stage. One reason could be related to the di culty to nd the right balance between activity and toxicity for such systems.…”

“…While for the applications of conventional mRNA, as well as for modi ed mRNA (modRNA), lipid-based nanoparticles have proven to be successful for delivery, for saRNA, polymer-based systems have been identi ed to be particularly effective (5)(6)(7). Polyethylenimine (PEI) is a clinically established cationic polymer for nucleotide delivery, which has demonstrated e cacy in combination with saRNA (5).…”

mRNA-encoded HIV-1 Env trimer ferritin nanoparticles induce monoclonal antibodies that neutralize heterologous HIV-1 isolates in mice

“…Several studies published recently explored the use of mRNAs for HIV-1 vaccines in various forms, such as self-amplifying mRNA ( Aldon et al., 2021 ; Melo et al., 2019 ) or mRNA-encoded virus-like particles ( Zhang et al., 2021 ). These studies highlighted the versatility of mRNA vaccine platform for HIV-1 vaccine development and stressed the need for careful studies to compare and evaluate different mRNA technologies.…”

Ex Vivo Evaluation of Mucosal Responses to Vaccination with ALVAC and AIDSVAX of Non-Human Primates

“…Total and anti-gp120 HIV-1 CM244 -specific IgG and IgA levels were measured with Rhesusmacaque-specific in-house semi-quantitative ELISAs, as described previously [10,40,41]. Briefly, for the quantification of total Ig medium-binding 96-well ELISA plates (Greiner Bio-one, Kremsmünster, Austria) were coated overnight at 4 • C with 100 µL/well of goat α-human Kappa and goat α-human Lambda (SouthernBiotech, Birmingham, AL, USA) captures antibodies (diluted 1:1200 for IgG or 1:1000 for IgA) at a 1:1 ratio.…”