A multimeric L2 vaccine for prevention of animal papillomavirus infections.

It is unclear what level of neutralizing antibody is sufficient to protect cattle from experimental bovine papillomavirus type 4 (BPV4) challenge. Markedly lower, and often undetected, serum neutralizing antibody titers were associated with protection in cattle vaccinated with BPV4 L2 as compared to L1 VLP. We hypothesized that vaccination with concatemers of the N-terminal protective epitopes of L2 derived from multiple animal papillomavirus types would enhance the breadth and strength of immunity. Therefore we generated a multimeric L2 antigen derived from three bovine and three canine papillomavirus types with divergent phenotypes and purified it from bacteria. Mice vaccinated three times with this six type L2 vaccine formulated in alum or RIBI adjuvant generated robust serum neutralizing antibody titers against BPV1, BPV4 and canine oral papillomavirus (COPV). Furthermore, vaccination with this six type L2 vaccine formulated in adjuvant, like BPV1 L1 VLP, protected the mice from experimental challenge with BPV1 pseudovirus.