Formula X (House of the Dead)

Formula X was a mutagen developed for military purposes. Samples were hidden in an underground bunker, which was discovered by prison warden Clement Darling. His experimentation with Formula X caused a mutant outbreak in Bayou City, Louisiana.

In When the Cold Breeze Blows Away, it would be discovered in during USRAC War that Papa Caesar or Clement Darling would making their experiments or Formura X unidentified enemies

Therefore,Delilah Medici is the one who created the combination of T-Virus and Formula X named Formula T-Virus,which caused the Schadelerian Infection