Figure 2.

Potential mechanisms of vertical transmission of oral HPV infection (sequentially ordered: from left to right, from 1a to 1d and from 2a to 2b). Infection can occur with transplacental transmission or at the time of delivery. In infants, vertical transmission can occur through breastfeeding or direct contact as they go along. The virus can manifest itself through multiple low-risk HPV (LR-HPV)-related lesions, such as in respiratory papillomatosis, or it can persist in the airways of infants, establishing a significant reservoir of HR-HPV that may increase the risk of carcinogenesis in adulthood.