definiens: means ( i ) the PTC Compounds, ( ii ) the Schering Compounds, and ( iii ) any compound that is an Active Compound and is either ( x ) first synthesized, or identified as a Vi ral IRES Inhibitor, by PTC or Schering, or any of their respective Affiliates, or any Third Party working in collaboration with or on behalf of PTC or Schering or any of their respective Affiliates, following the Effective Date in the cou rse of performing work under the Research Program, or ( y ) claimed or covered in a Patent that claims a Program Invention, together in the case of both ( x ) and ( y ) with any metabolites and prodrugs, and any solvates ( including without l imitation hydrates ), esters, salts, stereoisomers, racemates, tautomers and poly morphs, of any such compound that are themselves Active Compounds or are convert ed to an Active Compound in vivo