The Establishment of a Noninvasive Bioluminescence-Specific Viral Encephalitis Model by Pseudorabies Virus-Infected NF-κBp-Luciferase Mice

Abstract

Encephalitis is a rare brain inflammation that is most commonly caused by a viral infection. In this study, we first use an in vivo imaging system (IVIS) to determine whether NF-κBp-luciferase expression could be detected in the brain of pseudorabies virus (PRV)-infected NF-κBp-luciferase mice and to evaluate proinflammatory mediators in a well-described mouse model of PRV encephalitis. In in vitro studies, we used murine microglia (BV-2) cells to demonstrate the PRV-induced encephalitis model entailing the activation of microglia cells. The results indicate that PRV-induced neuroinflammation responses through the induction of IL-6, TNF-α, COX-2, and iNOS expression occurred via the regulation of NF-κB expression in BV-2 cells. In in vivo studies, compared with MOCK controls, the mice infected with neurovirulent PRV exhibited significantly elevated NF-κB transcription factor activity and luciferase protein expression only in the brain by IVIS. Mild focal necrosis was also observed in the brain. Further examination revealed biomarkers of inflammation, including inducible cyclooxygenase (COX)-2, inducible nitric oxide synthase (iNOS), and tumor necrosis factor (TNF)-α and interleukin (IL)-6, both of which constituted proinflammatory cytokines. PRV infection stimulated inflammation and COX-2 and iNOS expression of IL-6 and TNF-α. The presented results herein suggest that PRV induces iNOS and COX-2 expression in the brain of NF-κBp–luciferase mice via NF-κB activation. In conclusion, we used NF-κBp-luciferase mice to establish a specific virus-induced encephalitis model via PRV intranasal infection. In the future, this in vivo model will provide potential targets for the development of new therapeutic strategies focusing on NF-κB inflammatory biomarkers and the development of drugs for viral inflammatory diseases.