Article Title: Immunogenicity and Neutralizing Activity Comparison of SARS-CoV-2 Spike Full-Length and Subunit Domain Proteins in Young Adult and Old-Aged Mice
Figure Lengend Snippet: Adjuvanted S and S1 immune sera exhibit high titers of SARS-CoV-2 pseudovirus neutralization and receptor binding inhibition activities. ( A – C ) Reduction percentage (%) in relative luminometer units (RLU) as a measure of luciferase activity for SARS-CoV-2 spike pseudotyped lentivirus infection in HEK293 cells expressing human ACE2 receptor. Data were obtained from pooled sera ( n = 6 to 8) with triplicate wells. S-0.8 (y): S 0.8 µg boost sera of young adult mice, S-0.8 + adj (y): S 0.8 µg + adjuvant boost sera of young adult mice, S-0.8 + adj (a): S 0.8 µg + adjuvant boost sera of old aged mice, S1-4 (y): S1 4 µg boost immune sera of young adult mice, S1-4 + adj (y): S1 4 µg + adjuvant boost immune sera of young adult mice, S2-4 (y): S2 4 µg boost immune sera of young adult mice, S2-4 + adj (y): S2 4 µg + adjuvant boost immune sera of young adult mice, S-0.8 + adj (y, x3): S 0.8 µg + adjuvant 2nd boost immune sera of young adult mice, S-0.8 + adj (y, x3, 19W): S 0.8 µg + adjuvant immune sera collected at week 19 post 2nd boost of young adult mice, S-4 + adj (a, x3): S 4 µg + adjuvant 2nd boost sera of old aged mice. IV-0.8-10 + adj (y, x3): inactivated adjuvanted SARS-CoV-2 vaccination in young age mice (prime 0.8 µg of heat-inactivated and gamma-irradiated virus, 2 times boost with 10 µg inactivated adjuvanted SARS-CoV-2 of heat-inactivated and gamma-irradiated virus). Adj: adjuvants (MPL + QS-21, 1 µg + 10 µg). Mock: sera from mice with adjuvant (MPL + QS-21, 1 + 10 µg) only. ( D – F ) ACE2 receptor binding inhibition titers in pooled immune sera ( n = 6–8) with triplicate wells. Inhibition percentage (%) of hACE2 binding to RBD was measured after incubation with serially diluted immune sera in the plate precoated with hACE2 protein. Immune sera of groups are the same as in ( A – C ). Statistical significance was calculated using two-way ANOVA and a Bonferroni’s multiple-comparison test. Error bars indicate the mean ± SEM. **; p
Article Snippet: Recombinant Proteins and ReagentsSARS-CoV-2 different recombinant S and receptor proteins were obtained from Sino Biologicals (Wayne, PA, USA): Full-length S (S1–S2) ectodomain amino acid (aa) residues 16-1213 (40589-V08B1, 134.36 kDa, expressed in baculovirus-insect cells), S1 subunit (aa 16-685) with RBD domain (40591-V08H, 76.5 kDa, expressed in HEK293 cells); S2 subunit (aa 686-1213) with fusion domain (40589-V08B1, 59.36 kDa, expressed in baculovirus-insect cells); human angiotensin-converting enzyme 2 (hACE2) protein (aa 1-740) fused to Fc tag (10108-H02H, expressed in HEK293 cells).
Techniques: Neutralization, Binding Assay, Inhibition, Luciferase, Activity Assay, Infection, Expressing, Mouse Assay, Irradiation, Incubation