HUMAN PAPILLOMAVIRUS TYPE-6 AND TYPE-11 HAVE ANTIGENICALLY DISTINCT STRONGLY IMMUNOGENIC CONFORMATIONALLY DEPENDENT NEUTRALIZING EPITOPES

Antibodies reactive to HPV types 6 and 11 were tested in ELISA and HPV -11 neutralization assays to determine whether these closely related t ypes shared cross-reactive neutralizing epitopes. A series of HPV-11 n eutralizing monoclonal antibodies (N-MAbs) that targeted conformationa l epitopes on infectious HPV-11 and HPV-11 L1 virus-like particles (VL Ps) were tested for type-specificity of reactivity using intact HPV-6 L1 VLPs. Polyclonal antisera generated against intact HPV-6 L1 VLPs we re also tested for HPV-11 neutralizing capacity using the athymic mous e xenograft system. The results demonstrated that conformationally dep endent neutralizing epitopes on HPV-11 were Very type-specific. Three of the four HPV-11 N-MAbs were negative for binding to HPV-6 L1 VLP, a nd the fourth demonstrated binding to HPV-6 L1 VLPs that was several o rders of magnitude weaker than its binding to HPV-11 L1 VLP. The polyc lonal anti-HPV-6 L1 VLP antiserum was only partially protective agains t HPV-11 infectivity even at a low dilution of 1:100. In contrast, pol yclonal anti-HPV-11 L1 VLP antiserum was completely protective at dilu tions greater than 1:10,000. (C) 1994 Academic Press, Inc.