Prevalence of single and multiple infection with human papillomaviruses in various grades of cervical neoplasia

Evaluation of human papillomavirus (HPV) diversity in various grades of cervical lesions is helpful for understanding the characteristics of HPV infection in the pathogenesis of cervical neoplasia. A total of 227 women with normal cervices (n = 72), low- and high-grade cervical squamous intraepithelial lesions (SILs) (n = 55 and 53, respectively) and cervical carcinomas (n = 47) were screened for human papillomavirus (HPV) types 6, 11, 16 and 18 infection by the polymerase chain reaction. The prevalence of multiple HPV infections in patients with normal cervices, low-grade SILs, high-grade SILs and cervical carcinomas was 22.2%, 61.8%, 41.5% and 21.3%, respectively, while the prevalence of a single-type infection was 36.1%, 21.8%, 30.2% and 61.7%, respectively. HPV 16/11 and 16/18 were the most common combinations observed in multiple infections. Multiple HPV infections were seen most frequently in patients with low-grade SILs, and the prevalence decreased with increasing severity of cervical neoplasia. In contrast, infection with a single HPV type was most commonly observed in patients with cervical carcinoma, and the prevalence decreased with decreasing severity of cervical neoplasia. HPV 16 was the predominant single-type infection in patients with cervical carcinoma and this prevalence decreased steadily with decreasing severity of cervical neoplasia. Conversely HPV 11 was the predominant single-type infection in patients with normal cervices. This prevalence decreased with increasing severity of cervical neoplasia. Patients with low-grade SILs had a higher prevalence of HPVs, regardless of single or multiple infection status, and larger copy numbers of virus genome were seen more frequently in patients with more severe lesions.