The study involves two GMOs. ChAdOx1-HPV is a recombinant replication-incompetent chimpanzee-derived adenovirus (ChAdY25) viral vector. MVA-HPV is a modified vaccinia virus Ankara vector (MVA). Both vectors encode a fusion of sequences derived from HPV.
The nOPV2 candidate strains include different combinations of 5 distinct modified regions of the Sabin-2 genome, including changes to the RNA sequence in the 5’ untranslated region of polio genome (5’ UTR), the capsid protein coding region (P1), the non-structural protein 2C, and the polymerase 3D. Of these modifications, only the changes to polymerase 3D result in a change in the amino acid sequence. The rest of the modifications aim to stabilize the genetic sequence against reversion in either the 5’ UTR or capsid regions.