IN-VIVO EXPRESSION OF AN INTERFERON-ALPHA GENE BY INTRAMUSCULAR INJECTION OF NAKED DNA

Acid-stable type I interferons belong to a multigene family, The biolo gic relevance of each subtype in vivo remains unknown, We have develop ed an experimental model in which muscles were transfected in situ wit h naked DNA plasmids encoding an IFN transgene to assess the roles of individual IFN subtypes in vivo, Murine IFN-alpha 9 gene was subcloned into several mammalian expression vectors, Adult C57BL/6 mice were in jected bilaterally in regenerating tibialis anterior muscles with nake d DNA 5 days after muscle injury to enhance DNA uptake and expression. In the muscles of mice given the IFN-alpha 9 plasmid constructs, acid -stable IFNs were detected by bioassay using reduction in cytopathic e ffect of encephalomyocarditis virus-infected L929 cells, In these same muscles, IFN-alpha 9 transcripts were identified by RT-PCR, indicatin g that transcription had occurred, Acid-stable IFNs were detected from days 7 to 28 post-DNA inoculation, Furthermore, these proteins were f ound in the sera of DNA-inoculated mice, Control groups of mice given the blank expression vectors did not produce detectable IFNs in muscle or sera as determined by bioassay, nor were transcripts detected by R T-PCR, This approach now allows investigation of the effector function of individual subtypes in various murine disease models.