Rotavirus infection of children at-risk of type 1 diabetes is associated with disease progression. Similarly, infection of adult non-obese diabetic (NOD) mice with Rhesus monkey rotavirus RRV accelerates diabetes onset. This acceleration correlates with RRV spread to the mesenteric and pancreatic lymph nodes, where virus associates with and activates dendritic cells and induces B and T cell activation. We also have shown that RRV exposure ex vivo induces generalized B and T cell activation by triggering toll-like receptor 7 (TLR7) signaling and type I interferon production by plasmacytoid dendritic cells (pDC) from NOD mice. As this activation includes islet autoantigen specific T cells, we hypothesize that type I interferon-mediated bystander activation contributes to diabetes acceleration by RRV in NOD mice. Notably, RRV induces significantly more activation of NOD mouse than C57BL/6 mouse cells, providing evidence that these responses to RRV are heightened in mice at-risk of T1D. Influenza virus and coxsackievirus B, which also signal through TLR7, have been shown to induce heightened pDC-dependent type I interferon responses in PBMCs from T1D patients compared to controls. We hypothesize that rotavirus will also induce heightened pDC-dependent lymphocyte activation and type I interferon secretion in PBMCs and other immune cells from patients with T1D compared to controls. Therefore, the overall aim of our study is to evaluate activation and type I interferon expression following stimulation with rotavirus in immune cells from patients with T1D compared to controls.