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. Author manuscript; available in PMC: 2023 Oct 27.
Published in final edited form as: Nat Biotechnol. 2022 Jun 13;40(11):1680–1689. doi: 10.1038/s41587-022-01347-6

Fig. 6 |. Using dqTACT to monitor the persistence of cellular immunity and cross reactivity with spike epitopes from VOC in vaccinated participants.

Fig. 6 |

a–c, Detection of CXCL10 mRNA (dqTACT (a)), IFN-γ protein secretion (ELLA (b)) or IFN-γ producing cells (ELISpot (c)) in vaccinated participants over time. Time points (postvaccination) are indicated on the x axis and relative CXCL10 expression (a), IFN-γ protein secretion (b) or IFN-γ producing cells (c) on the y axis (all values minus DMSO). The dashed lines represent the dqTACT (0.003), ELLA (5) or ELISpot (5) thresholds. d, Schematic to show how T cell responses against the VOC can be evaluated using the delta variant as an example. Orange regions refer to amino acid mutations present in the delta variant compared to the wildtype (WT) SARS-CoV-2 strain. Pool HS (hotspot) contains peptides covering the nonconserved Spike-Wuhan regions affected by mutations present in the delta variant (24 peptides). Pool delta MT contains peptides from Pool HS with the amino acid mutations present in the Spike protein of the delta variant. e–g, Quantification of CXCL10 mRNA (dqTACT (e)), IFN-γ protein secretion (ELLA (f)) or IFN-γ producing cells (ELISpot (g)) in vaccinated participants stimulated with spike peptides covering the hotspot wildtype (HS WT) or delta variant region. The peptide pool used for stimulation, either the wildtype (HS) or delta (delt) sequence, is indicated on the x axis and relative CXCL10 expression (e), IFN-γ protein secretion (f) or IFN-γ producing cells (g) on the y axis (all values minus DMSO). The dashed lines represent the dqTACT (0.003), ELLA (5) or ELISpot (5) thresholds. P values were calculated using a two-sided Wilcoxon rank sum test. h,i, Quantification of relative CXCL10 mRNA expression using dqTACT (h) or IFN-γ protein section using ELLA (i) in an elderly cohort. For a–c and e–i, the box bounds represent the first quartile (bottom), median (center) and the third quartile (top). The whiskers represent the range of samples up to 1.5 times the interquartile range. Beyond this point, the samples are shown as outliers. The number of participants for each time point is indicated above the box plots along with the percentage of participants who fall above the threshold.