Figure 3From: Serum indoleamine 2,3-dioxygenase activity is associated with reduced immunogenicity following vaccination with MVA85A Serum IDO activity is higher in South African compared to UK adults. A) Serum IDO activity was measured in serum using LC-MS to quantity L-Trp and L-Kyn in participant serum. The ratio of L-Trp/L-Kyn gives a measure of IDO enzyme activity in host serum. B) IDO activity was assessed in serum from UK and South African adults at baseline (pre-vaccination, week 0) and 1 week following immunisation with MVA85A. Mann Whitney was used for comparison between groups (*P < .05).Back to article page