Type-specific detection of human papillomaviruses in a routine laboratory setting--improved sensitivity and specificity of PCR and sequence analysis compared to direct hybridisation.

Abstract

Human papillomaviruses (HPV) are known to cause cervical dysplasia and cervical carcinoma. We used a 3-step PCR protocol that allows rapid type-specific HPV testing in a routine laboratory setting: HPV-16-positive samples were determined using a specific LightCycler PCR; HPV-16-negative samples were amplified by nested PCR and typed by sequence analysis. During a period of 7 months, 1275 PCR-based HPV tests were performed. Of the 1275 samples, 829 samples tested negative for HPV and 446 tested positive, including 124 positives found in the initial HPV-16-specific LightCycler assay. Sequence analysis of 132 samples detected 18 HPV types that are not included in the widely used Hybrid Capture II assay. For comparison, the first 100 cervical specimens were tested in parallel using PCR and direct hybridisation (Hybrid Capture II assay). PCR detected HPV DNA in 23 samples that tested negative in the Hybrid Capture assay. Four out of 37 samples that tested positive for HPV in the Hybrid Capture test may be false positives, because sequence analysis detected HPV types not included in the probe mixtures. As rare and novel HPV types may also confer an oncogenic risk, highly sensitive and specific PCR assays will help in understanding cervical HPV infection and cervical cancer of unknown causes.