A scalable and highly immunogenic virus-like particle-based vaccine against SARS-CoV-2.

BACKGROUND: SARS-CoV-2 caused one of the most devastating pandemics in the recent history of mankind. Due to various countermeasures, including lock-downs, wearing masks, and increased hygiene, the virus has been controlled in some parts of the world. More recently, the availability of vaccines, based on RNA or adenoviruses, has greatly added to our ability to keep the virus at bay; again, however, in some parts of the world only. While available vaccines are effective, it would be desirable to also have more classical vaccines at hand for the future. Key feature of vaccines for long-term control of SARS-CoV-2 would be inexpensive production at large scale, ability to make multiple booster injections, and long-term stability at 4℃. METHODS: Here, we describe such a vaccine candidate, consisting of the SARS-CoV-2 receptor-binding motif (RBM) grafted genetically onto the surface of the immunologically optimized cucumber mosaic virus, called CuMVTT -RBM. RESULTS: Using bacterial fermentation and continuous flow centrifugation for purification, the yield of the production process is estimated to be >2.5 million doses per 1000-litre fermenter run. We demonstrate that the candidate vaccine is highly immunogenic in mice and rabbits and induces more high avidity antibodies compared to convalescent human sera. The induced antibodies are more cross-reactive to mutant RBDs of variants of concern (VoC). Furthermore, antibody responses are neutralizing and long-lived. In addition, the vaccine candidate was stable for at least 14 months at 4℃. CONCLUSION: Thus, the here presented VLP-based vaccine may be a good candidate for use as conventional vaccine in the long term.

Synthetic bacterial lipopeptide analogs: structural requirements for adjuvanticity.

Modern vaccines aim at conferring immune protection, independently of the nature of the etiological agent causing the disease. These new therapeutics are based on highly purified antigenic moieties that offer potential advantages over traditional vaccines, including a high degree of safety and the capacity of eliciting highly specific immune responses. In spite of these advantages however, subunit vaccines tend to be poorly immunogenic in vivo, and require the coadministration of adjuvants that indirectly enhance cellular immunity. Thus, recombinant vaccines development is dependent on the design of new molecules, non-immunogenic per se, but endowed with immune modulatory properties. Synthetic analogs of bacterial lipoproteins were described more than a decade ago, but their capacity to act as adjuvants has been only recently dissected. These low molecular weight non-immunogenic molecules can be reproducibly synthetized, are safe, and of easy handling and administration. Furthermore, new experimental data from our laboratory reveal their powerful adjuvant effect on human HLA-I/II restricted T cell responses and identify the molecular and cellular requirements for optimal adjuvanticity.

Synthetic bacterial lipopeptide analogs facilitate naive CD4+ T cell differentiation and enhance antigen-specific HLA-II-restricted responses.

Synthetic di- and tri-palmitoylated bacterial lipopeptide analogs (BLpA) can enhance HLA-I-restricted immune responses. Here we show that BLpA indirectly promote antigen-driven differentiation of naive CD4+ T lymphocytes in vitro, with mechanisms that require DC and are inhibited by CTLA-4/Ig. In mixed cultures of cord blood-derived PBMC and allogeneic DC, P3CSK4 lipopeptide facilitated the transition from CCR7(+)/CD45RA(+)/CD62L+ to CCR7(-)/CD45RA(-)/CD62L(dim) T cells with kinetics significantly exceeding those obtained with the unlipidated CSK4 analog. Moreover, P3CSK4 and P2CSK4, but neither the mono-palmitoylated PCSK4 analog nor the CSK4 peptide, increased the frequency of IFN-gamma-producing T cells expanded under similar conditions. Along with this, P2CSK4 and P3CSK4, but not PCSK4, restored the in vitro antigenicity of MDP-OspA, a non-immunogenic analog of Borrelia burgdorferi major outer surface lipoprotein A, and enhanced the frequency of in vitro expanded T cells specific for the tetanus toxoid (TT) and hepatitis B surface antigen (HBsAg) peptides TT(947-967) and HBsAg(19-33) and for TT. Altogether, BLpA bearing at least two ester-bonded palmitoyl side chains indirectly enhance antigen-driven CD4+ T cell differentiation. BLpA adjuvanticity is independent of covalent bonding to Ag and Ag formulation. This information may be helpful to generate more potent recombinant vaccines.

Pretreatment cytokine profiles of peripheral blood mononuclear cells and serum from patients with rheumatoid arthritis in different american college of rheumatology response groups to methotrexate.

OBJECTIVE: To determine the role of putative target cytokines for methotrexate (MTX) treatment in patients with rheumatoid arthritis (RA) as predictors for treatment outcome. METHODS: Fifty consecutive patients with RA were characterized according to demographic and disease associated features and followed prospectively before and after 6 months of treatment with MTX. Before starting MTX treatment, serum was obtained from each patient and peripheral blood mononuclear cells (PBMC) were isolated. PBMC were cultured 2 days under resting conditions, and interleukin 1 receptor antagonist (IL-1ra), IL-1beta, soluble tumor necrosis factor receptor p55+75 (sTNFR p55+p75), and TNF-a release into cell culture supernatants and corresponding serum cytokine levels were determined by specific ELISA. Constitutive production and circulating levels of cytokines and cytokine inhibitors were correlated to the clinical response after 6 months of MTX treatment, and patients were categorized into 4 different groups according to the American College of Rheumatology (ACR) response criteria (ACR < 20, 20-50, 50-70, > 70% improvement from baseline). RESULTS: Good (ACR 50-70) or excellent (ACR > 70) responses to MTX treatment were seen in groups of patients with a higher proportion of males (25 and 43%) associated with a significantly lower ratio of IL-1ra/IL-1beta (p < 0.00001) constitutively produced by PBMC (ratio < 100) compared with nonresponding (ACR < 20) patients (males 7.7%; ratio > 100). The ratios in 3 female poor responders (ACR 20-50) were in between. The decreased ratios of IL-1ra/IL-1beta in most good and excellent responders were due to an enhanced constitutive IL-1beta release from PBMC (p < 0.004) compared to the groups of non or poor responders. Much less pronounced, there was a slightly significant increase of sTNFR p55 shedding from PBMC and increase of sTNFR p75 serum levels in good and excellent responders (both p < 0.02). In contrast, there were no intergroup differences regarding constitutive IL-1ra release, sTNFR p75 shedding, and IL-1ra and sTNFR p55 serum levels and various demographic and disease associated characteristics of patients. CONCLUSION: Determination of cellularly produced IL-1beta and even more of the IL-1ra/IL-1beta synthesis in PBMC may be useful to predict the outcome of RA patients undergoing treatment with MTX and may characterize a subset of RA that is more responsive to IL-1 directed therapeutic interventions.