Detection protocols for biotinylated probes: optimization using multistep techniques

Recent studies using biotinylated in situ hybridization (ISH) have utilized a wide range of detection protocols for the biotinylated hybrids, leading to conflicting reports in the literature regarding sensitivity. In this study we compared 11 different detection protocols for biotinylated ISH using a measles virus-specific RNA probe on formalin-fixed, paraffin-embedded central nervous system tissue infected with measles virus. Maximum sensitivity was achieved with five-step detection protocols incorporating the use of a monoclonal antibody to biotin. Single-step detection protocols were found to be insensitive, as shown by their failure to detect viral nucleic acid in infected white-matter cells. Only by increasing the number of steps in the detection protocols were these infected cells demonstrable. Unless pre-hybridization, hybridization, and detection protocols are optimized, the results obtained in pathogenicity studies using ISH could be misinterpreted, leading to false conclusions about nucleic acid distribution. This also applies to the ever-increasing use of ISH for diagnostic purposes.