High performance Nanogold-silver in situ hybridisation.

Conventional in situ hybridisation (ISH) usually requires the presence of at least 10-50 copies of the nucleic acid sequence in question per cell. In situ PCR has been proposed as an alternative method, which may yield single-copy sensitivity, but shows a relatively high rate of false-negative or even false-positive reactions. Very recently, possible alternatives have been described, which can be performed in routine laboratories without the need for expensive equipment. Streptavidin-Nanogold-Silver ISH is an easy-to-perform assay, which can be applied to detect low copy numbers of nucleic acid sequences in paraffin sections and cytological preparations. Its combination with labelled tyramides (TSATM = tyramide signal amplification, also known as CARD = catalysed reporter deposition) can achieve single gene copy sensitivity in detecting DNA viruses and also shows very high sensitivity for RNA detection. Possible applications include the early recognition of viral infection, cancer-associated genes, genetic diseases, and also the specific detection of mRNA.