Insights into the role and function of L2, the minor capsid protein of papillomaviruses.

Human papillomaviruses (HPV) are responsible for the most common human sexually transmitted viral infections, and high-risk types are responsible for causing cervical and other cancers. The minor capsid protein L2 of HPV plays important roles in virus entry into cells, localisation of viral components to the nucleus, in DNA binding, capsid formation and stability. It also elicits antibodies that are more cross-reactive between HPV types than does the major capsid protein L1, making it an attractive potential target for new-generation, more broadly protective subunit vaccines against HPV infections. However, its low abundance in natural capsids--12-72 molecules per 360 copies of L1--limits its immunogenicity. This review will explore the biological roles of the protein, and prospects for its use in new vaccines.