D

D., Verrington K., Wan H., Pessaint L., Van Ry A., Knife K., Strasbaugh A., Cabus M., Brown R., Cook A., Zouantchangadou S., Teow E., Andersen H., Lewis M. for any low-cost modular vaccine platform for SARS-CoV-2 and other variants of concern or betacoronaviruses. INTRODUCTION Prophylactic vaccination is effective in eliciting protective immunity against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and preventing coronavirus disease 2019 (COVID-19) ((( 0.1, Kolmogorov-Smirnov test) than the vaccine formulated with both alum and CpG 1018. Neutralization of SARS-CoV-2 pseudovirus correlated well with spike proteinCspecific antibody titer (fig. S2A). Open in a separate windows Fig. 2. Humoral and cellular immune response to the RBD-VLP vaccine.(A) Design of the nonhuman primate study in cynomolgus macaques. (B) Titers of RBD-specific antibody binding in animal sera. (C) Titers of SARS-CoV-2 pseudovirusCneutralizing antibody in animal sera. NT50, end point of 50% reduction of computer virus expression. (D) Expression of IFN- from Alimemazine D6 cells stimulated with S1 protein peptides. Statistical significance was determined by a Kolmogorov-Smirnov test. n.s., not significant ( 0.1). Black bars symbolize median values. Gray dotted line represents limit of detection. PBMCs, peripheral blood mononuclear cells. We also assessed the neutralizing activity of sera from week 5 against SARS-CoV-2 pseudoviruses with spike proteins from several circulating variants of concern (fig. S2B). Sera from animals immunized with RBD-VLP in both vaccine formulations exhibited comparable neutralizing activities against D614G and B.1.1.7 variants. While changes in the neutralizing activities of sera from animals immunized with RBD-VLP with alum and CpG 1018 against B.1.351 were not statistically significant, the neutralizing activities of sera from animals immunized with RBD-VLP with only alum were significantly reduced against B.1.351 (~25, geometric mean). To determine why the formulation with only alum elicited higher antibody titers, we assessed the antigenicity for retained samples of the RBD-VLP in both vaccine formulations used. We observed ~30% less binding to human ACE2 for the alum and CpG 1018 formulation compared to the formulation with alum only [competitive enzyme-linked immunosorbent assay (ELISA)] (fig. Alimemazine D6 S2C). The formulation with alum and CpG 1018 at the concentrations used here appears to either have altered the antigenicity of the RBD-VLP antigen or destabilized the SpyTag/SpyCatcher-mediated linkage of RBD and VLP, potentially leading to a reduced humoral immune response. After assessing the humoral response to the RBD-VLP vaccine candidate, we profiled the cellular immune response. We assessed expression of interferon- (IFN-) in cells stimulated with peptides from your S1 region of the spike protein, which includes the RBD (Fig. 2D). We observed significant IFN- expression in cells from both the alum formulation and the alum and CpG 1018 formulation after two doses. The cellular response appeared stronger with the alum and CpG 1018 coformulation, consistent with previous reports around the influence of CpG 1018 as an adjuvant in vaccines ( 0.4, Kolmogorov-Smirnov test). Challenge with SARS-CoV-2 To assess whether the RBD-VLP vaccine could protect animals from contamination, we challenged all animals with SARS-CoV-2 2 weeks after the second immunization Rabbit Polyclonal to Cytochrome P450 26C1 (Fig. 2A). We monitored the course of contamination for 2 weeks by measuring titers Alimemazine D6 of subgenomic RNA (sgRNA) in nasal swabs and bronchoalveolar lavage (BAL) supernatants. Both formulations of the RBD-VLP vaccine significantly reduced the levels of detected sgRNA in the upper respiratory tract (Fig. 3A), and no sgRNA was detected on day 4 after challenge from your group immunized Alimemazine D6 with RBD-VLP formulated with alum (Fig. 3B). Both RBD-VLP formulations exhibited nearly complete protection from viral contamination in the lower respiratory tractsgRNA was detected in BAL supernatants from only three animals (Fig. 3, C and D). We observed significant correlation between prechallenge antibody titers and measured sgRNA levels (Fig. 3, E and F). Open in a separate windows Fig. 3. Challenge with SARS-CoV-2.(A and C) Peak levels of SARS-CoV-2.