Figure A4.
Adenovirus DNA copies in rabbit blood upon immunization. Each dot represents DNA copies/10 µL blood from an individual rabbit, of which the presence of vector DNA is measured in three technical replicates (n = three per rabbit). Both adenovirus vectors used in the study (Ad26.COV2.S and Ad26.ZIKV.001) contained a transgene cassette with a CMV promoter. The primer–probe set used in the ddPCR assay was designed to amplify a sequence from this CMV promoter. For each group (n = five rabbits per group, except for the IV buffer control group, where four samples were available), the difference with the group dosed IV with 5 × 109 vp/kg of Ad26.COV2.S was assessed (ANOVA on log10 [average per rabbit] with separate variance per group). Each line represents the arithmetic mean of the DNA copies per rabbit in each group; horizontal lines represent respective group means. Threshold (dotted line) is defined as the highest value of the negative control. ** p < 0.01. *** p < 0.001. Ad26, adenovirus type 26; ANOVA, analysis of variance; CMV, cytomegalovirus; ddPCR, droplet digital polymerase chain reaction; IM, intramuscular; IV, intravenous; n.s., not significant; vp, viral particles.