A comparison of biotin- and 35S-based in situ hybridization methodologies for detection of human papillomavirus DNA

In situ hybridization is commonly used for the detection of human papillomavirus (HPV) DNA in genital tract lesions. Systems based on biotin complexes are quicker and easier to use than 35S-based systems, although reportedly less sensitive. We compared three in situ hybridization systems for HPV DNA detection: two biotin [PathoGene DNA probe assay [Enzo Diagnostics] and Viratype in situ HPV probes and HPV tissue hybridization kit [Life Technologies Inc. (LTI)] and one 35S based. By using serial sections from 80 female genital tract lesions with the histologic features of an HPV infection, sequences homologous to HPV DNA were detected in 59 cases (74%) with the LTI system and 25 cases (31%) with the Enzo system. The Enzo system uses a streptavidinbiotinylated horseradish peroxidase complex and 2% 3-amino-9-ethylcarbazole as the chromogen. The LTI system uses a streptavidin alkaline phosphatase conjugate in which the chromogen is 5-bromo-4-chloro-3-indolylphosphate in the presence of nitroblue tetrazolium. Replacing the Enzo detection system with the LTI detection system increased the sensitivity of the Enzo kit. The LTI biotin system was equally sensitive when compared against 35S-labeled HPV probes. The sensitivity with the biotin probes, reported to be less than the 35S probes in a previous study (Lab Invest 58:354, 1988), was increased if the current LTI detection system replaced the detection system used in that study. It is concluded that biotin-labeled DNA probes can be equally sensitive to 35S-labeled DNA probes for the detection of sequences homologous to HPV DNA. The enhanced sensitivity for the biotin system is primarily due to improved detection of the probe/target complex.