Project Summary The Hybrid Rat Diversity Program (HRDP) at the Medical College of Wisconsin (MCW) is pleased to submit this administrative supplement for support during the current grant year (ending January 31, 2025). The overall goal of the HRDP program is to extend the use of rat models for clinical translation through establishing an animal resource and genomic dataset to facilitate the translation of laboratory research to clinical relevance. The HRDP parent project has successfully established ~80% of the panel, including the entire FXLE/LEXF recombinant inbred panel and nearly all of the classic inbred strains. The HXB/BXH recombinant inbred panel currently has only 14 strains available to the biomedical research community due to a limited number of embryos available, challenges associated with the BN strain contribution to rederivation attempts, and pathogen status of a subset of embryos and strains. This supplement application proposes to complete the HXB/BXH recombinant inbred panel through the import of 17 rat strains from the Czech Academy of Sciences in Prague to the Medical College of Wisconsin. Living colonies of the remaining HXB/BXH strains are available from Dr. Pravenec’s lab at the Czech Academy of Sciences. However, these strains are on the verge of elimination due to a lack of financial support and pending retirement of Dr. Pravenec. This supplement aims to 1) to identify healthy, pathogen free rats for each of the 17 strains, 2) prepare and ship these rats with a tracking system to ensure successful transfer of the strains, and 3) establish colonies of these strains using quality control measure for health status and strain identity. The most efficient and cost-effective approach to acquire these key HRDP strains is by importing pathogen free rats from the Czech Republic to MCW. The rat strains and associated genomic and phenotypic data will be made available to the research community.