Fig. 1

Experimental design. a A healthy individual was vaccinated with Fluarix Quad 2016–2017 vaccine and after 7 days CD38+ CD27+ plasmablasts were single-cell sorted into 96-well plates using flow cytometry. 10 μL lysates were aliquoted to single-cell RNA-seq (9 μL) and nested RT-PCR (nested RT-PCR (1 μL)) to sequence the immunoglobulin heavy (IgH) and light (IgL) chain genes. b ELISPOT assay of day 7 post-vaccination plasmablasts that shows IgH isotype usage and specificity of the plasmablast population for influenza vaccine. c Bioanalyzer plots of single-cell sequencing libraries after SMART-Seq v4 amplification for a plasmablast and a peripheral blood CD19+ B cell. The peaks in the plasmablast plot match in nt sequence length to the full-length heavy and light chain genes. Ig immunoglobulin gene, IgH immunoglobulin heavy chain gene, IgL immunoglobulin light chain gene