Current amphibian decline due to infections is devastating for biodiversity and ecosystem health. Interferons (IFNs) are key immune genes that are important mediators of antitumor and antiviral responses. Understanding the function of amphibian IFNs is fundamental to directly addressing infections that are causing current amphibian declines. This project seeks to understand the signature role of amphibian IFNs in IFN evolution and functional diversification in vertebrates. IFNs originated in jawed fish from the multi-exon progenitors. Recent research by the principal investigator detected the unexpected emergence and expansion of intronless IFN genes in amphibians. This discovery revises the established model of IFN evolution and highlights that amphibians are critical for studying IFN biology in vertebrates. This project will examine the role of the intronless IFNs during frog development and protection against viral infection. Completion of this project will provide a unique and previously unknown platform to address immune evolution, functional capacity, and especially amphibian defense against viral infections. This award will promote collaboration between major research universities and a Historically Black College and University (HBCU). It will provide research training and strengthen biology education at the HBCU. <br/><br/>Knowledge regarding the molecular origin and functional diversification of IFN genes in vertebrates is fragmentary. In particular, little is known about amphibian IFNs. Previous studies have discovered only several intron-containing IFN progenitors in amphibians and have underestimated IFN-mediated immune responses in amphibians and the actual role of amphibians in IFN evolution. As a key node in immune evolution, functional understanding of amphibian IFN complex and its reaction to pathogenic infections is fundamental to the study of immunobiology in vertebrates. Using laboratory Xenopus models, the proposed research will (1) comparatively profile the expression of intron-containing and intronless IFN subgroups during frog development and infection, (2) determine the functional capacity and evolutionary superiority of newly evolved intronless IFNs against the viral infection, (3) determine the dependence of amphibian IFN ligands on canonical IFN signaling pathways to induce effector genes and induce antiviral activity. These complimentary contributions will functionally characterize the IFN complex in amphibians, and ultimately fill a knowledge gap in IFN evolution. In addition, the proposed research will integrate collaborative efforts of the PI/Co-PIs at Tennessee State University (TSU), Vanderbilt University, and the University of Rochester to accomplish the objectives. It will train HBCU research personnel at two prominent research institutes and enhance research excellence and broaden STEM education at the minority-serving institution.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.