Increase of integration events and infection loads of human papillomavirus type 52 with lesion severity from low-grade cervical lesion to invasive cancer

Infection load and the integration of human papillomaviruses (HPV) have been implicated as determinants for oncogenesis, but whether variation among different HPV types exists remains unclear. We investigated 91 women infected with HPV type 52 (HPV-52), a type that is rare worldwide but common in East Asia. The median viral load increased with the severity of the lesion (248 copies/cell equivalent for normal/cervical intraepithelial neoplasia [CIN] grade 1, 402 copies/cell equivalent for CIN 2, 523 copies/ cell equivalent for CIN 3, and 1,435 copies/cell equivalent for invasive cancer). The proportion of specimens with integration increased significantly with the severity of the lesion (P < 0.001). The viral load was associated with the physical status of the viral genome, with higher levels for the pure episomal form (P = 0.001). Infection status should be considered when interpreting viral load data for HPV-52, as single infections with this HPV type were found to have marginally higher viral loads than coinfections (P = 0.051). All except one sample had E2 disruption restricted to only a part of the gene. Integration is a critical step in HPV-52-induced carcinogenesis. The profile of E2 disruption was different from that described for HPV-16, with the amino-terminal region being most frequently involved. Selecting the appropriate E2 region for amplification is critical in studying the integration of HPV-52. In summary, the HPV-52 viral load and the integrated proportion increased with the severity of the cervical lesions but had a different pattern than that of HPV-16.