MedEngine Oy 1 article published in JoVE Immunology and Infection Immunization of Adult Zebrafish for the Preclinical Screening of DNA-based Vaccines Henna Myllymäki*1, Mirja Niskanen*1, Kaisa Oksanen1,2, Mika Rämet1,3,4,5 1BioMediTech Institute, Faculty of Medicine and Life Sciences, University of Tampere, 2MedEngine Oy, 3Department of Pediatrics, Tampere University Hospital, 4Department of Children and Adolescents, Oulu University Hospital, 5PEDEGO Research Unit, Medical Research Center, University of Oulu Here we describe a protocol for the immunization of the adult zebrafish (Danio rerio) with a DNA-based vaccine and demonstrate the validation of a successful vaccination event. This method is suitable for the preclinical screening of vaccine candidates in various infection models.