PMC9682080_01
Specific post-vaccination humoral response -level (U/ml, positive cut-off value > 18 U/ml, marked as dashed line) of specific anti-RBD SARS-CoV-2 IgG antibodies measured by ELISA at months 1 (M1) and 3 (M3) in healthy controls (HC) and patients with Fibrodysplasia ossificans progressiva (FOP, M- male patient #1, F- female patient #2) (A); titer (1:X) of specific anti-SARS-CoV-2 neutralizing antibodies at M1 in HC and FOP (B); level (U/ml, positive cut-off value > 180 U/ml, marked as dashed line) of specific anti- SARS-CoV-2 specific IgG antibodies (spike S1; spike S2; NCP, nucleocapsid protein; RBD, receptor-binding domain) measured by immunoblot (IB) at M1 (C), and M3 (D) in HC and FOP.
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After the three month follow-up period, neither clinical signs of disease flare nor any new HO formation at the injection site was detected using US examination in either patient ( Supplementary Figures 2A, B ). SARS-CoV-2 responses were detected using ELISA in both FOP patients following vaccination. Specific antibody concentrations were comparable to healthy controls (HC) (mean 972.1 U/ml vs. 1,000 U/ml) ( Figure 2A ). The humoral post-vaccination response was confirmed using western blot assay in both groups: mean concentration of anti-RBD SARS-CoV-2 antibodies was 967.8 U/ml (FOP patients) vs. 986.1 U/ml (HC) ( Figure 2C ). Other anti-SARS-CoV-2 antibodies (anti-NCP, anti-spike 2) were detected below the upper reference limit, suggesting no previous exposure to COVID-19 in either cohort in month 1 ( Figure 2D ). The high level of anti-RBD SARS-CoV-2 antibodies persisted as measured by ELISA (mean 1,000 U/ml) and WB (976.8 U/ml) in the third month ( Figures 2A, D ). However, the high titers of anti-NCP and anti-spike 2 specific antibodies were detected in patient 1, reflecting a convalescent state ( Figure 2D ). The detected anti-SARS-CoV-2 antibodies had virus-neutralizing activity in both FOP and HC individuals, with no differences in their titers (mean titer 1:240, range 1:160-1:320 vs. 1:320) ( Figure 2B ).
Specific post-vaccination cellular response - measured as percentage (%) of CD4+ T cells producing TNFalpha (A) or IFN-gamma (B) in unstimulated cells (NS) and after stimulation (STIM) at month 1 in healthy controls (HC) and patients with Fibrodysplasia ossificans (FOP, M- male patient #1, F- female patient #2).
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A higher IFN-gamma response was detected in patients after SARS-CoV-2 infection (male patient) ( Figures 3A, B ).