Exploiting the fact that vaccination and immunity to yellow fever is not prevalent in the developed world, we demonstrate that within the yellow fever vaccine response of a HLA B*57:01 positive individual we can detect a breadth of CD8+ T-cell clonotypes that recognise both the yellow fever wildtype KF9 epitope and synthetic variants of this epitope that can only be presented in an abacavir treatment dependent manner. Here, CD8A is linked to viral infectious disease.