University of California Irvine Health 1 article published in JoVE Immunology and Infection Use of an Influenza Antigen Microarray to Measure the Breadth of Serum Antibodies Across Virus Subtypes Saahir Khan1, Aarti Jain2, Omid Taghavian2, Rie Nakajima2, Algis Jasinskas2, Medalyn Supnet2, Jiin Felgner2, Jenny Davies2, Rafael Ramiro de Assis2, Sharon Jan2, Joshua Obiero2, Erwin Strahsburger2, Egest J. Pone2, Li Liang2, D. Huw Davies2, Philip L. Felgner2 1Division of Infectious Diseases, Department of Medicine, University of California Irvine Health, 2Vaccine Research and Development Center, Department of Physiology, University of California Irvine We present a protocol for using a protein microarray constructed by printing influenza antigens onto nitrocellulose-coated slides to simultaneously probe serum for multiple antibody isotypes against over 250 antigens from different virus strains, thus allowing measurement of the breadth of serum antibodies across virus subtypes.