Molecular identification of 7 human papillomavirus types in recurrent respiratory papillomatosis.

BACKGROUND: Recurrent respiratory papillomatosis (RRP) is the most frequent benign neoplasm in childhood; it originates as a mild dysphonia and results in asphyxia. The RRP has been associated with an infection caused by human papillomavirus (HPV), mainly types 6 and 11, the latter being associated with more severe RRP. OBJECTIVES: To analyze the frequency of the association of RRP with the HPV types in our juvenile population and to classify it according to severity. DESIGN: Observational descriptive trial. MATERIALS AND METHODS: Forty-seven samples of paraffin-embedded papillomas, from 26 female and 21 male children (age range, 2 weeks to 17 years) were analyzed. DNA was isolated and a 188-base pair fragment was amplified from a consensus sequence in the E1 open reading frame of several HPVs by polymerase chain reaction. The corresponding band was recovered and reamplified. The fragment was digested with the restriction enzyme RsaI. The digestion products were compared with patterns of molecular weight markers for viral type identification. The patients' clinical records were reviewed, and RRP was classified as mild or aggressive. RESULTS: The presence of HPV types 6, 11, 16, 31, 33, 35, or 39 was confirmed in all the cases with different combinations. The chi(2) test showed no significant differences in clinical aggressiveness among the viral types. A logistic regression analysis demonstrated no association between clinical aggressiveness and any viral type or viral combination. CONCLUSION: These results show that RRP is caused by infection with HPV types 6 and 11 in addition to many other types, with no relationship between HPV type and clinical severity.