HAdV-C5 is known to interact with coagulation factor X (FX) in blood, via the hexon protein, which mediates transduction of the liver and resulting in hepatotoxicity.16, 17, 18 High levels of HAdV-C5 pre-existing immunity in some populations may reduce the clinical efficacy of potential HAdV-C5-based oncolytic virotherapies,19, 20, 21, 22, 23 where a significant proportion of the population will have previously experienced an acute adenovirus infection and developed neutralizing immunity against common HAdV serotypes.24 This evidence concerns the gene C5 and adenoviridae infectious disease.