Abstract The field of Osteoimmunology was established in 2005 to understand how bone influences immune and hematopoietic cells, as well as how hematopoietic and immune cells influence bone, in clinical conditions like osteomyelitis. However, several critical research tools and rigorously validated protocols required to translate discoveries into clinical diagnostics and interventions for osteomyelitis did not exist at the commencement of this P50 Center of Research Translation on the Osteoimmunology of Bone Infection (CoRTOBI) 5 years ago. Thus, we assembled a multidisciplinary team of investigators with extensive experience in bone pathology, microbial pathogenesis, immunology, electron microscopy, biophysics, material science & engineering, infectious disease and orthopaedic surgery, to enable several breakthroughs in the field that serve as the scientific premise of this renewal application. Despite these major advances, additional assay and technology development is needed to complete the long-term goals of CoRTOBI. Thus, the renewal goals of the Osteoimmunology Research Core are to: 1) provide the CoRTOBI investigators with state-of-the-art bone infection research resources that do not exist elsewhere; and 2) develop novel technologies and assays for future osteoimmunology research on bone infection. Our approaches to achieve these goals are embodied by the following Specific Aims. In Aim 1 we will process the samples and perform all of the electron microscopy (EM) on the infected bone and fabricated nanoporous membranes in Project 1, the mRNA vaccine studies in Project 2, and external collaborations, using EM methods published during the prior funding period. In Aim 2.1 we will fabricate all of the µSiM-CA devices needed for novel antibiotic drug screening. In Aim 2.2 we will develop and validate novel µSiM-OLCN devices to assess haptotaxis and durotaxis behaviors of S. aureus in vitro to elucidate the mechanism of S. aureus invasion and colonization of the OLCN of cortical bone during chronic osteomyelitis, and in Aim 2.3 the Core will develop surface coatings on the µSiM-CA and µSiM-OLCN chips to enable hypothesis testing of S. aureus adhesion and rigidity during asymmetric binary fission. In Aim 3.1 we will perform all of Luminex-multiplex assays for immune proteome and cytokine analyses, and In Aim 3.2 we will translate this experimental assay for research into a same-day, high throughput clinical diagnostic called StaphAIR based on Arrayed Imaging Reflectometry technology that allows for the automated measurement of anti-S. aureus antibodies in near-real time. The Osteoimmunology Core will also facilitate emerging technologies and research in the Pilot and Feasibility Project Program (i.e. intravital microscopy to quantify “the race for the surface” during S. aureus colonization of bone implants; automated tape-collecting ultra-microtome (ATUMtome)/SEM methods for 3D imaging of infected OLCN; and an extension of StaphAIR). Importantly,...