Schematic of amplification and ligation in the existing oligonucleotide ligation assay (OLA).

<p>The <i>pol</i> gene of HIV DNA is amplified by nested PCR. Note that the HIV DNA gene map positions are not to scale. A portion of the amplicon is mixed with three oligonucleotide probes: a 5’ fluorescein (F) -conjugated mutant (MUT)-specific HIV probe; a 5’ digoxigenin (D) -conjugated wild-type (WT)-specific probe; and a 5’ phosphorylated, 3’ biotin (B) -conjugated common probe. When specific probes are complementary at the mutation site, they are ligated to the common probe to create a DNA strand with labels at both ends. Only ligated products are detected during the CDD procedure (surface <u><b>c</b></u>apture, <u><b>d</b></u>enaturation of oligonucleotide from target DNA, and enzyme-based detection).