Fig. 4: Anti-vector immunity.

a Titer of neutralising antibodies (nAbs) against ChAd3 vector (dotted line at nAb titer of 18, limit of detection for the assay). Volunteers who received ChAd3-NSmut prime and MVA-NSmut boost as part of arm A2 which were then reboosted in arm A4 are indicated by red symbols. Trial week indicates weeks since first vaccination for arm A2 and A3 and time of second ChAd3 vaccination for Arm A4. b Anti-ChAd3 nAb titer at baseline vs. peak magnitude of T cell responses to NS region of HCV post-vaccination (IFNγ ELISpot; spot forming cells per 10⁶ PBMC). c Anti-ChAd3 nAb titer at time of second ChAd3-NSmut vaccination vs. fold change in magnitude of T cell responses to HCV NS post-vaccination. Fold change (FC) was calculated as (total NS response 2 weeks post-vaccination—NS response on day of second ChAd3-NSmut vaccination)/NS response pre-vaccination. d Ex vivo T cell response to Ad5 hexon (IFNγ ELISpot; horizontal dotted line at 48, positivity cut-off for the assay). Trial week indicates weeks since first vaccination for arm A2 and A3 and time of second ChAd3 vaccination for Arm A4. e T cell response to Ad5 hexon at baseline vs. peak magnitude of T cell responses to NS region of HCV post-vaccination. f T cell response to Ad5 hexon at time of second ChAd3-NSmut vaccination vs. fold change in magnitude of T cell responses to HCV NS post vaccination (FC calculated as above). a, d Paired Wilcoxon t test. b, c, e, f Spearman rank correlation. ChAd3, chimpanzee-derived adenovirus 3; EOS, end of study. NS, non-structural; MVA, modified vaccina Ankara.