Validation of hybridization assays: correlation of filter in situ, dot blot and PCR with Southern blot

A number of validation experiments have compared the most commonly used HPV hybridization methods with the accepted gold standard, Southern blot hybridization. The methods discussed are filter in situ hybridization (FISH), dot blot hybridization (ViraPap/ViraType), and polymerase chain reaction (PCR). FISH now appears to be too inaccurate to be recommended for future epidemiological studies. ViraPap/ViraType compares well to Southern blot, but is limited to the detection of seven genital HPV types. PCR-based methods may be more sensitive than Southern blot and are likewise capable of detecting most known genital HPV types. Direct comparisons of the several available PCR methods should be performed. Currently, there is no perfect method for HPV testing, because Southern blot itself is prone to some errors in performance and interpretation. Given that the scientific and clinical usefulness of HPV tests depends on the repeatability and accuracy of the assays, more intra- and inter-assay comparisons should be done to establish reference standards applicable to this area of molecular diagnostics.