Acinetobacter baumannii rOmpA vaccine dose alters immune polarization and immunodominant epitopes

► Higher doses of the rOmpA anti-Acinetobacter baumannii vaccine induced higher vaccine titers. ► Higher dose of the rOmpA vaccine induced more polarized Type 2 immune response. ► Distinct rOmpA peptides preferentially induced IFN-γ or IL-4T cell responses. ► Higher vaccine dose induced epitope spreading for IL-4 producing lymphocytes. ► Higher vaccine dose induced epitope restriction for IFN-γ producing lymphocytes.