Both CRP, measured with high-sensitivity nephelometry assay (Roch

Both CRP, measured with high-sensitivity nephelometry assay (Roche Diagnostics, Indianapolis, IN) and ALC (derived from the CBC) were performed commercially (ACM Global Laboratory, Rochester, NY). IP-10 and IL-6 ELISAs are described below. Cellular responses were evaluated 7 days after the second administration of vaccine. Antibody responses were evaluated to determine anti-PA IgG levels in serum samples collected on Day 0, 14, 28, 42, and 70 (this paper) and toxin-neutralizing antibody (TNA) levels [14]. Prior to the first vaccine dose, and 7 days after the second vaccine dose (study day 21), PBMC were isolated from venous blood

samples, and stored in liquid nitrogen vapors at SeraCare Life Sciences (Gaithersburg, MD). For ELISpot controls: stimulants were phytohaemmaglutinin (PHA; mitogen, control for viability, Sigma, St Louis, MO) and CEF I peptide pool (Cellular Technology Ltd; Shaker Heights, OH) representing HLA Class I-restricted peptides from cytomegalovirus, Epstein Bar virus and influenza virus (CEF). Recall antigens were rPA (Emergent BioSolutions, Gaithersburg, MD) or a pool of 10 PA-derived peptides (PAps) (ProImmune, Oxford, UK). Sequences for PAps were selected on the basis of (1) high binding scores calculated by SYFPEITHI [15] and PROPRED

[16] in silico programs, (2) predicted binding by multiple HLA Class II types, (3) low hydrophobicity and (4) absence of Hydroxychloroquine mw cytotoxicity to naïve PBMC. Stimulation by PAp mixture was performed with a final concentration of 10 μg/mL of each peptide. PAp amino acid sequences and restricting next HLA haplotypes are listed in Table 2. PBMC were thawed in serum-free medium, re-suspended to a density of 1–2 × 106 viable cells/mL, rested overnight at 37 °C, 5% CO2, recounted and adjusted to target viable cell densities. For IFN-γ ELISpot, stimulants and antigens (50 μL) were delivered to 96-well plates (SeraCare LifeSciences),

followed by PBMC (50 μL per well, 300,000 cells; or 100,000 cells for PHA wells). Final volume per well was 100 μL. PHA was tested in duplicate wells and all others in triplicate. PBMC from a single-donor (SeraCare Cat. # 1074) which responded to CEF I stimulation with IFN-γ production, were included in every plate to assess experimental variability. After 40–48 h of incubation, IFN-γ spot forming cells (SFC) were enumerated using an ELISpot plate reader (Cellular Technology Ltd.). A specificity rate of 100% and a sensitivity rate of 79% were achieved using SFC counts at cut-off levels of ≥200 for PHA- and ≥15 for CEF I-stimulated cells. Specificity and sensitivity rates were lower if fewer SFC for PHA and CEF I were analyzed. Serum samples obtained at study sites were stored at −70 °C until assayed.

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