Identification of vaccine human papillomavirus genotypes in squamous intraepithelial lesions (CIN2-3).

OBJECTIVE

To identify the prevalence of human papillomavirus vaccine genotypes and non-vaccine genotypes implicated in the appearance of cervical intraepithelial neoplasia (CIN2-3).

METHODS

Prospective study of 519 women with abnormal cytology. All the women underwent a second Papanicolaou test, cervicovaginal sampling for type-specific HPV detection and colposcopy, and women with abnormal colposcopy results were referred to biopsy. Pearson's chi-square test was used for statistical analysis.

RESULTS

HPV was detected in 340 patients (65.5%), and in 125 (24%) more than one HPV genotype was present. We selected 206 patients with CIN2 or CIN3 confirmed by biopsy. In 88 (42.7%) of these patients, HPV types 16 and 18 were detected, but only 58 (28.2%) without co-infection by other high-risk or probable high-risk HPV types. In 115 (55.8%) women diagnosed with CIN2 or CIN3 high-risk or probable high-risk HPV types other than 16 or 18 were found. High-risk and/or probable high-risk HPV genotypes not included in the vaccine were isolated in this study more frequently than 16 or 18, and this difference was statistically significant (p=0.047). Of the 206 women diagnosed with CIN2 or CIN3, 19 tested negative for HPV and 14 tested positive for low-risk HPV types.

CONCLUSION

Only 28.2% of women with CIN2 or CIN3 confirmed by biopsy were infected exclusively by HPV type 16 or 18, a finding that places in doubt the degree of protection afforded by HPV vaccination.