Correlation of HPV16 L1 capsid protein expression in cervical dysplasia with HPV16 DNA concentration, HPV16 E6*I mRNA and histologic outcome.

OBJECTIVE: To determine whether the absence ofHPV1i6 LI capsid protein is a prognostic parameter for the histologic outcome of cervical intraepithelial neoplasia (CIN) 2+ in cytologically diagnosed cervical dysplasia. STUDY DESIGN: Papanicolaou-stained microscopic slides of 95 HPV16-positive cervical samples that had a cytologic diagnosis of cervical dysplasia or borderline cytology were immunostained using an HPV16-specific anti-L1 viral capsid antibody. In parallel to the cytologic examination, HPV16 DNA and E6*I mRNA were quantitated using real-time polymerase chain reaction. Expression of L1 protein was correlated with relative levels of HPV16 DNA and E6*I mRNA as well as histologic diagnoses/cytologic follow-up. RESULTS: Thirty-five cases with a histologic diagnosis of CIN 2+ (61%) were negative for HPV16 L1 protein; 22 (39%) were positive. Of the cases that either were CIN 1 or regressed to normal cytology, 10 cases (26%) were positive for HPV16 L1 protein, while 28 (74%) were negative. L1-negative and L1-positive cases showed no statistically significant difference (p = 0.22) in their histologic diagnosis/cytologic follow-up. The positive predictive value for CIN 2+ was 56% if L1 protein was absent; the negative predictivre value for CIN 1/regression to normal cytology was 31% if L1 protein was present. HPV16 Ll-positive cases had significantly higher HPV16 DNA concentrations than L1-negative cases (p < 0.001), while levels of HPV16 E6*I mRNA were comparable in both types of cases (p = 0.36). CONCLUSION: The expression of HPV16 L1 capsid protein is correlated with viral DNA load but does not predict the histologic outcome of HPV16-positive cervical dysplasia.

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

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.