The expression, localization, and effect of a human interferon in plants.

The ORF II of Cauliflower mosaic virus (CaMV) DNA was replaced with the human IFN alpha D coding sequence to yield a stable CaMV strain designated Ca524i. Inoculation of turnip (Brassica rapa cv "Just Right") with strain Ca524i DNA excised from plasmid pCa524i resulted in the production of biologically active IFN alpha D in infected plants. This was also true for its mutant (Ca562i) where one of the CYS codons was deleted. IFN alpha D produced in planta did not hamper superinfection with a single-stranded (+) sense RNA plant virus, turnip yellow mosaic virus (TYMV). Antibody gold labeling techniques and electron microscopy of infected plants showed that IFN was localized in the CaMV inclusion bodies.