The majority of the neutralizing epitopes of papillomaviruses (PV) are conformation-specific and have not been fully characterised.
Studies have, to date, been limited to a few HPV types only. We analysed the epitopes on the major capsid protein (L1) of
Human papillomavirus (HPV) type 31 using monoclonal antibodies (MAbs) generated against HPV-31 virus-like particles (VLPs).
The type-specific MAbs against HPV-31 were all found to be neutralizing and recognized conformation-dependent epitopes. Two
other MAbs directed against a conformational epitope were found to be cross-reactive with other HPV types, and one of them
was found to be cross-neutralizing. Cross-reactive antibodies were further investigated using wild-type HPV-16 L1 VLPs and
two mutants. The results obtained suggested the existence of a cross-neutralizing conformational epitope at the N-terminal
part of the FG loop of the major capsid protein, and the other four cross-reactive MAbs recognized epitopes also located at
the N-terminal part of the FG loop.