(4S)-4-{N-[(1S)-2-indol-3-yl-1-({[5-(5-methyl-2,4-dioxo(1,3-dihydropyrimidinyl))(2-2,5-dihydrofuryl)]methyl}oxycarbonyl)ethyl]carbamoyl}-4-aminobutanoic acid AIDS-095355 AIDS095355 Thymogen-2',3'-didehydro-3'-deoxythymidine conjugate