Phase 1 Novel Live Attenuated Serotype 2 Oral Polio Vaccine Study in Inactivated Polio Vaccine (IPV) Primed Adults

"Live-attenuated serotype-2 poliovirus derived from a modified Sabin type-2 infectious cDNA clone and propagated in Vero cells; candidate 1 (S2/cre5/S15domV/rec1/hifi3).~Modifications included the following:~* Changes to the viral nucleotide sequence in part of the 5'-untranslated region to improve the genetic stability of this major attenuating determinant of Sabin type-2 to avoid reversion by single nucleotide changes.~* Two modifications in the polymerase 3D to further improve stability of the attenuation and reduce frequency of recombination events~* Relocation of a key replication element from the 2C coding region to the 5'-untranslated region, to inhibit recombination."

"Live-attenuated serotype-2 poliovirus derived from a modified Sabin type-2 infectious cDNA clone and propagated in Vero cells; candidate 2 (S2/S15domV/CpG40).~Modifications included the following:~* Changes to the viral nucleotide sequence in part of the 5'-untranslated region to improve the genetic stability of this major attenuating determinant of Sabin type-2 to avoid reversion by single nucleotide changes.~* silent non-coding modifications engineered within the capsid (VP1-4) designed to reduce replicative fitness and, potentially, to improve stability of the attenuated phenotype while also reducing transmission."