Mice with type 1 diabetes exhibit increased susceptibility to influenza A virus

Type 1 diabetes (T1D) is a metabolic disease induced by abnormal insulin secretions from damaged islet B cells. Clinical observations have shown that T1D patients are more easily infected by influenza A virus (IAV) and suffer more serious symptoms than non-T1D patients. To investigate the susceptibility of T1D mice to IAV, a T1D mouse model was built by intraperitoneal injection of diluted streptozotocin (STZ) over 5 consecutive days, followed by infection with three subtypes of IAV (H1N1/H5N1/H7N2). The T1D-infected mice showed more serious clinical symptoms and lower survival rates than the non-T1D infected mice. The hematoxylin and eosin (H & E) staining results revealed an increase in serious pathological damage to the lung and pancreas in T1-Dinfected mice. Immunohistochemistry results indicated higher IAV loads and a more extensive distribution of positive signals in the lungs and pancreas of T1D-infected mice than in those of non-T1D infected mice. Furthermore, according to real-time quantitative polymerase chain reaction (PCR) results, viral replication appeared to occur more easily in the lungs of T1D-infected mice. Thus, T1D-infected mice exhibited higher susceptibility to IAV than did normal mice. This study contributes a mouse model suitable for T1D research as well as valuable information about the mechanism underlying T1D patients' increased susceptibility to IAV.