Use of Automated BaseScope Assay on the Leica BOND RX.

The in situ hybridization assay, BaseScope™, detects RNA transcripts in their spatial context, in settings in which enhanced detection is required. Such high sensitivity might be necessary because the target has: (a) low copy number of the target nucleic acid sequence in the cells of interest makes detection challenging with other methodologies, (b) a short target nucleic acid sequence (e.g., 50-300 nucleotides) limiting the number of probes that can be placed along it, (c) very closely related sequences from which it needs to be specifically discriminated. BaseScope™ enables the targeting of RNA sequences using as few as one to three pairs of 18-25 bp antisense oligonucleotide probes, combined with a highly sensitive chromogenic detection method. This assay can be performed on either the Leica BOND RX or the Ventana Discovery Ultra staining platforms; however, this chapter specifically focuses on the automated BaseScope™ assay using the Leica BOND RX platform.