Structures for abacavir, CBV-TP, and deoxyguanosine triphosphate (dGTP). Note the similarities in structure between CBV-TP and dGTP, excluding the absence of the critical free 3’-OH group on the deoxyribose sugar ring in CBV-TP. This absence prevents the addition of any additional nucleotides and blocks further viral DNA synthesis. CBV-TP, (–)-carbovir 5’-triphosphate.