Provided herein are methods of detecting an antibody directed against a pathogen and uses thereof. One aspect provided herein relates to a method for detecting an antibody against a pathogen in a subject, the method comprising: (a) contacting a reaction sample comprising a display library with a biological sample comprising antibodies, wherein the display library comprises a plurality of peptides derived from a plurality of pathogens, and (b) detecting a peptide bound to at least one antibody, thereby detecting an antibody capable of binding the peptide.