Viral Infection of Transgenic Mice Expressing a Viral Protein in Oligodendrocytes Leads to Chronic Central Nervous System Autoimmune Disease

Evans, Claire F.; Horwitz, Marc S.; Hobbs, Monte V.; Oldstone, Michael B.A.

Tissue specific expression of the transgenes was demonstrated by RT-PCR ( Fig. 1 B ) . Oligonucleotide primers were designed to take advantage of the PLP intron within the vector. By amplifying a product across the intron as shown in Fig. 1 A , spliced mRNA could be distinguished from both unspliced mRNA as well as contaminating genomic DNA. RT-PCR product that corresponded in size to correctly spliced RNA message was identified in the brains of 7 out of 8 MBP-NP lines and in 7 out of 7 MBP-GP lines. An RT-PCR survey of RNA from various organs did not detect transgene-specific message in the liver, kidney, spleen, pancreas, lung, heart, or sciatic nerve. However, ‫ف‬ 25% of the lines showed spliced RNA transgene expression in the thymus. Two MBP-NP (5 and 60) and two MBP-GP (36 and 46) lines with only CNS expression of the transgenes were chosen for further study (Fig. 1 , B and C ) and bred to the F4 level to BALB/c and C57BL/6J mice, respectively. Immunohistochemical approaches (in situ immunohistochemistry and Western blot) were undertaken to identify the transgene products in brain tissue; however, these attempts were unsuccessful. Protein expression in the MBP-NP and -GP mice is likely below the level of sensitivity of antibody detection. Previous attempts at identifying LCMV gene products expressed as a transgene of the rat insulin promoter in the ␤ cells of the Islets of Langerhans had also failed (19) . However, these transgenic mice were subsequently shown to express the transgene as shown by CTL recognition of pancreatic ␤ cells, T cell recognition being at least two logs more sensitive than antibody recognition (28, 29) .