Figure 3.

Possible HPV transmission routes. Two routes of HPV infection of the mammary epithelium are plausible. First, direct contact between an infected epithelium and the mammary epithelium. In this way, the virus can enter through microlesions that would allow infection and the expression of viral oncoproteins, which in collaboration with other factors can account for a breast tumor. On the other hand, extracellular vesicles (EV), which can be released to the bloodstream by HPV-infected cells, can transfer viral biomolecules to the breast. These biomolecules (EV cargo: proteins, nucleic acids, microRNAs) may go on to collaborate with other factors in tumor development.