Establishment of disseminated neonatal echovirus 11 infection model in hFcRn transgenic mice

Echovirus 11 (E11) infections can easily cause neonatal sepsis, which is a life-threatening disease. However, the pathogenesis of E11 infections remains poorly understood. Furthermore, the absence of an effective animal model that accurately reflects disseminated neonatal infection has hindered research progress. Hence, we aimed to establish a precise disease mouse model closely resembling E11 associated human neonatal conditions. Three-day-old human neonatal Fc receptor (hFcRn) transgenic mice were administered an optimized dose of E11 through intraperitoneal (IP) injection. E11-infected mice exhibited severe clinical symptoms, including weight loss, limb paralysis, and even death. Viral loads were detected across multiple organs, such as muscle, spinal cord, and intestine, with the highest load in muscle (1 × 10⁵-1 × 10⁷ copies/mg). Additionally, liver and kidney function (ALT, AST and Cr), cardiac enzymes (CK-MB), and coagulation parameters (FDP) were markedly abnormal in the E11 group, in which ALT level showed 3.5 times higher than the normal group. Furthermore, in situ hybridization revealed E11 RNA in the heart, liver, lungs, and brain, with the highest levels in the heart and liver. Serum cytokine analysis showed significant elevation of MCP-1, IL-18, IL-22, and RANTES, with MCP-1 reaching levels as high as 2590 pg/mL. Histopathological examination revealed extensive pathological changes in multiple tissues. The successful establishment of the disseminated neonatal E11 infection model relies on several key factors, including the use of 3-day-old mice, an increased dosage of the infectious agent, an appropriate infection route via IP injection, and the use of viral strains obtained from the clinical case of neonatal mortality. In summary, this mouse model serves as a valuable tool for investigating the pathogenic mechanisms of E11 infection associated disseminated neonatal infection, offering a stable platform for the development and evaluation of related vaccines and therapeutic drugs.