The final aim of this challenge is to discover whether there exist rules able to predict reactivity of peptides with human antibodies. These rules can be used to develop new reactive peptides. The ''bonus round'' was conceived to test the rules learned during the main challenge: each team was required to submit a list of de-novo peptides generated using their predictive models; the list generated by the teams that achieved the top performance in the main challenge will be experimentally validated by the DREAM5 organizers.