MPXV197 inhibits TCR-dependent T cell stimulation.

<p><b>A)</b> CM9-specific CD8+ T-cells were incubated (18 h) with untreated CHO cells (UN) or CHO cells transduced with either Ad-197/Ad-tTA (‘Ad-197’) or Ad-tTA only (‘Ad-control’) and stimulated with CM9-peptide pulsed BLCLs. The percentage of INFγ+ TNFα+ CD8+ T-cells was determined by ICCS. <b>B)</b> To determine the kinetics of T cell inhibition by MPXV197 CM9-specific T-cells were incubated with Ad-197/Ad-tTA or Ad-tTA-transduced CHO cells for indicated time periods, washed, and stimulated with peptide pulsed BLCLs. <b>C)</b> Human <i>Mtb</i> specific CD8+ T cell clones D466 D6 and D160 1–23 were stimulated with BEAS-2b cells transduced with Ad-197/Ad-tTA or Ad-tTA only in the presence of CFP10_2-12 peptide or pronase digested <i>Mtb</i> cell wall, respectively. For MHC-independent stimulation, both clones were incubated with PHA. The number of IFNγ+ T cells was measured by ELISPOT. <b>D)</b> CM9-specific CD8+ T cells were incubated (18 h) with CHO cells transduced with Ad-197/Ad-tTA or Ad-tTA, washed, and stimulated either with PMA/Iono or CM9-peptide pulsed BLCLs. <u>Left panel</u>: The percentages of INFγ+ TNFα+ T-cells were determined by ICCS with stimulation in the presence of uninfected CHO cells set to 100% (MAX). <u>Right Panel</u>: The percent live CD8+ T cells was determined by LIVE/DEAD Fixable Dead Cell Stain. <b>E)</b> MaMu-A*01/CM9 tetramer staining of CM9-pecific CD8+ T cells after 18 h of incubation with MPXV197-expressing CHO cells (‘Ad-197’) or control cells (‘Ad-control’).