A group of infection-enhancing and focus size-reducing monoclonal antibodies recognized an ‘a and c’ strands epitope in the pr domain of Dengue Virus prM

•Antibodies targeting 'a and c' strands of dengue pr have infection-enhancing activity.•Cross-reactive anti-prM antibodies lack strong neutralizing activity against dengue virus.•Some cross-reactive anti-prM antibodies reduce the focus size of dengue virus.•Focus size reduction occurs in a subset of viruses that an anti-prM antibody can bind.