The analysis of mechanism of Theiler's virus-induced damyelination in L* protein transgenic mice

点击翻译按钮获取中文摘要

Theiler's murine encephalomyelitis virus (TMEV) is classified into two subgroups based on the difference in biological activities. DA strain causes chronic inflammatory demyelination in the spinal cord in susceptible strains of mice. This serves as an experimental model of multiple sclerosis, human demyelinating disease in the central nervous system (CNS). The precise mechanism of persistent infection and demyelination by DA strain is yet to be elucidated. DA strain translates 17 kDa protein, designated L*, which is out of frame with the virus. To elucidate the mechanism of persistent infection of TMEV and demyelination, in this study we tried to generate transgenic mice expressing L* protein under different promoters. We generated the constructs which have L* protein cDNA under MHC class I or iNOS or chicken β-actin promoter. These constructs were injected into FVB/NJ mouse embryo. The expression of L* was not verified in vivo although robust expression of L* was observed in vitro. Therefore, we generated the immortalized macrophage cell line J774 expressing L* protein by using lentivirus vector. Macrophage is considered as the reservoir of TMEV in chronic phase of the disease. When J774 was infected with DAL*-1, which fails to synthesize L* and has attenuated demyelinating activity in the CNS, the virus failed to grow. In contrast, DAL*-1 virus was able to grow in J774 expressing L* indicating that L* is important to grow in macrophage. In addition, the mutant virus expressing epitope-tagged L* was generated and the L* expression in the CNS in acute phase of the disease was analyzed. In acute phase, L* was expressed in the CNS in both susceptible and resistant strains of mice suggesting that L* expression itself is not a determining factor of chronic infection and demyelination.