Inovio Pharmaceuticals, Inc 1 article published in JoVE Immunology and Infection Optimized Interferon-gamma ELISpot Assay to Measure T Cell Responses in the Guinea Pig Model after Vaccination Katherine Schultheis1, Hubert Schaefer2, Holly M. Pugh1, Bryan S. Yung1, Janet Oh1, Jacklyn Nguyen1, Laurent Humeau1, Kate E. Broderick1, Trevor R.F. Smith1 1Inovio Pharmaceuticals, Inc, 2Mycotic and Parasitic Agents and Mycobacteria, Robert Koch Institute The development of the interferon-gamma ELISpot assay for guinea pig PBMCs allows the characterization of T-cell responses in this highly relevant model for studying infectious diseases. We have applied the assay to measure T cell responses associated with intradermal delivery of DNA vaccines.