47 Alexander E. Kalyuzhny (ed.), Handbook of ELISPOT: Methods and Protocols, Methods in Molecular Biology, vol. 792, DOI 10.1007/978-1-61779-325-7_4, © Springer Science+Business Media, LLC 2012 Chapter 4 Utilization of Feline ELISPOT for Mapping Vaccine Epitopes Jeffrey R. Abbott, Ruiyu Pu, James K. Coleman, and Janet K. Yamamoto Abstract A commercial feline immunodeficiency virus (FIV) vaccine consisting of inactivated dual-subtype viruses was released in the USA in 2002 and released subsequently over the next 6 years in Canada, Australia, New Zealand, and Japan. Based on the genetic, morphologic, and biochemical similarities between FIV and human immunodeficiency virus-1 (HIV-1), FIV infection of domestic cats is being used as a small animal model of HIV/AIDS vaccine. Studies on prototype and commercial FIV vaccines provide new insights to the types of immunity and the vaccine epitopes required for an effective human HIV-1 vaccine. ELISPOT assays to detect cytokines, chemokines, and cytolytic mediators are widely used to measure the magnitude and the types of cellular immunity produced by vaccination. Moreover, such approach has identified regions on both HIV-1 and FIV proteins that induce robust antiviral cellular immunity in infected hosts. Using the same strategy, cats immunized with prototype and commercial FIV vaccines are being analyzed by feline interferon- and IL-2 ELISPOT systems to identify the vaccine epitope repertoire for prophylaxis. Key words: Feline interferon- ELISPOT, Feline IL-2 ELISPOT, Vaccine epitope mapping, Feline immunodeficiency virus, FIV vaccine, HIV-1 vaccine Numerous human immunodeficiency virus (HIV)/AIDS researchers have used the ELISPOT analysis system to evaluate the epitopes on the human immunodeficiency virus-1 (HIV-1) viruses that induce mediators of cell-mediated immunity (CMI), such as inter- feron- (IFN ), IFN , IL-2, tumor necrosis factor- (TNF ), and cytolytic mediators (e.g., perforins and granzymes) (1–3). The most widely used ELISPOT studies in HIV/feline immunodefi- ciency virus (FIV) research detect the cytokines IFN and IL-2. IFN and IL-2 ELISPOT assays are among the initial ELISPOT systems to be commercially available for both humans and cats. 1. Introduction