OP-32.01
DEVELOPMENT OF AAVLP(HPV16/31L2) PARTICLES AS BROADLY PROTECTIVE VACCINE
CANDIDATES
K Nieto, German Cancer Research Center, Heidelberg, Germany, S Sedlmeier, MediGene AG, Martinsried, Germany, P Sehr, EMBL, Heidelberg, Germany, M Ritter, MediGene AG, Martinsried, Germany, M Weghofer, MediGene AG, Martinsried, Germany, M Hörer, MediGene AG, Martinsried, Germany, U Michaelis, MediGene AG, Martinsried, Germany, M Müller, German Cancer Research Center, Heidelberg, Germany, L Gissmann, German Cancer Research Center, Heidelberg,
Germany, J Kleinschmidt, German Cancer Research Center, Heidelberg, Germany
Background: The minor capsid protein L2 is a promising candidate for a broadly protective HPV vaccine yet the titers obtained in most experimental systems are rather low. Adeno-associated viruses (AAV) have a favourable safety profile and hence can be used in humans. So far empty AAV particles (AAVLPs) have not been evaluated for delivery of foreign epitopes inserted within the capsid.
Objectives: To test AAVLPs presenting HPV L2 peptides for their ability to generate neutralizing antibodies against a spectrum of different HPV types.
Methods: L2 epitopes (aa17-36) from HPV16 and HPV31 were inserted in the capsid of AAV particles at positions 587 and 453 (AAVLP(HPV16/31L2)). These particles were applied intramuscular in rabbits and mice. Titers of HPV16 L2 IgG and neutralizing antibodies against six different HPV types (HPV16,18,31,45,52,58) and BPV were analysed by pseudovirion-based neutralization assay and compared to HPV16 L2 (aa20-38)-chimeric thioredoxin (TrXL2).
Results: The AAVLP(HPV16/31L2) particles induced very high titers of HPV16 L2 antibodies as measured by ELISA (around 100,000) and induced neutralizing antibodies against several HPV types in two mouse strains (C57/Bl6, Balb/c) and in rabbits. In C57/Bl6 mice, AAVLP(HPV16/31L2) particles induced neutralizing antibodies that were enhanced by adding Montanide whereas TrXL2-immunized mice (with Montanide) were mostly negative or had low titers. In Balb/c mice AAVLP(HPV16/31L2) particles (with Montanide) evoked comparable neutralizing activity. Using MPL as adjuvant
had no enhancing effect. Immunization with lyophilized AAVLP(HPV16/31L2) particles induced cross-neutralization but the titers were lower than with the non-lyophilized particles. Interestingly, immunization of animals that were preimmunized with AAV strongly increased cross neutralization of most of the HPV types tested.
Conclusions: AAV empty capsids can be generated presenting HPV L2 epitopes on their surface. Our results demonstrate cross neutralizing responses against several HPV types and therefore suggest AAVLP(HPV16/31L2) particles as a broadly protective vaccine candidate.Declaration of interest
The authors S. Sedlmeier, M. Ritter, M. Weghofer, M. Hörer and U. Michaelis are or have been employees of MediGene AG.
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