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The D-variant of encephalomyocarditis (EMC-D) virus was given to SJUJ mice by the artificial, intraperitoneal (ip) route of infection , or by the natural routes of infection per os (po) or intranasal (i.n .), in comparable concentrations. The po route of infection was found to be ineffective. Mice given virus by either the ip or i.n. routes of infection became diabetic. Mice were more resistant to the infectious and diabetogenic properties of the virus when given by the i.n. than when given by the ip route. Glycosuria in mice given virus i.n. usually lagged one day behind that in mice given virus ip. Measurement of glucose in mouse urine by use of Diastix® reagent strips was found to be a reliable indicator of diabetes. This test was easily and quickly accomplished without harm or pain to the mice. Crude virus preparations were compared to purified virus preparations for their diabetogenic and infectious properties in mice. No statistically significant differences in either parameter were observed. Virus prepared by a single passage in BHK-21 cells was fully diabetogenic, contrary to a previously published report. Male SJUJ mice were infected with a diabetogenic dose of EMC-D virus by the i.n. route. Relative times of development of virus infection and mouse resistance parameters were compared to the time of development of signs of diabetes in the mice. A rapid decrease of plasma interferon titer corresponded to the time of development of signs of diabetes in the infected mice. Whether this was coincidental or has some significance in development of diabetes is unknown. Tissue sections from pancreas, spleen , kidney, liver, lung , heart, and thymus were studied by immunohistochemical staining techniques for the presence of virus antigen, insulin, and the three types of mouse interferon (α, β, and γ). Glucose was excreted in the saliva of mice with glycosuria. Previous reports of this excretion in diabetic mice have not been found in the literature. Mice without glycosuria did not excrete measurable (by Clinistix® or Diastix®) glucose in saliva. Some mice were able to control the polyuria, polydipsia, and polyphagia normally seen in diabetes mellitus. These mice eventually reverted from having signs of diabetes to a normal state of plasma glucose and urine devoid of glucose. The mechanisms by which the mice were able to do this are unknown at this time.

Type 1 diabetes (T1D) is a chronic autoimmune disease characterized by the immune-mediated destruction of insulin-producing beta-cells of pancreatic islets, culminating in critical insulin deficiency. Both genetic and environmental factors likely orchestrate an immune-mediated functional loss of beta cell mass, leading to the clinical manifestation of disease and lifelong dependence on insulin therapy. Additional evidence suggests the role of innate and adaptive immune mechanisms leading to inflammation in beta cells mediated by proinflammatory cytokines and chemokines, activation of beta-cell-reactive T cells,and failure of immune tolerance. Viral infections have been proposed as causal determinants or initiating triggers for T1D but remain unproven. Understanding the relationship between viral infections and the development of T1D is essential for T1D prevention. Importantly, virus-induced innate immune responses, particularly type I interferon (IFN-I, IFN-a/b), have been implicated in the initiation of islet autoimmunity and development of T1D. The goal of my thesis project is to investigate how the IFN-I signaling pathway affects the development of T1D using the LEW.1WR1 rat model of autoimmune diabetes. My hypothesis is that disrupting IFN-Isignaling via functional deficiency of the IFN-I interferon receptor (IFNAR) prevents or delays the development of virus-induced diabetes.For this purpose, I generated IFNAR subunit 1(IFNAR1)-deficient LEW.1WR1 rats using CRISPR-Cas9 genome editing and confirmed the functional disruption of IFNAR1. The absence of IFNAR1 results in a significant delay in onset and frequency of diabetes following poly I:C challenge and reduces the incidence of insulitis after poly I:C treatment. The frequency of diabetes induced by Kilham rat virus (KRV) is also reduced in IFNAR1-deficient LEW.1WR1 rats. Furthermore, I observe a decrease in CD8+T cells in spleens from KRV-infected IFNAR1-deficient rats relative to that in KRV-infected wild-type rats. While splenic regulatory T cells are depleted in WT rats during KRV-infection, no such decrease is observed in KRV-infected IFNAR1-deficient rats. A comprehensive bulk RNA-seq analysis reveals a decrease of interferon-stimulated genes and inflammatory gene expression in IFNAR1-deficient rats relative to wild-type rats following KRV challenge. Collectively, the results from these studies provided mechanistic insights into the essential role of virus-induced, IFN-I-initiated innate immune responses in the early phase of autoimmune diabetes pathogenesis.