Fig. (4) Intracellular distribution of ORF3 and deletion mutants. (A) Schematic diagrams of ORF3 and deletion mutants. (B) PK-15 cells were transfected with recombinant plasmids containing defined coding region of ORF3, and incubated for 48 h. The intracellular distributions of ORF3 (a), ORF3N52 (b), ORF3N53-104 (c) were examined with mouse specific immune serum by IFA. The GFP fusion proteins containing different N-terminal tags of ORF3 subunits, N53-68 (d), N53-85 (e), and N85-104 (f) were visualized with a fluorescence microscope. The location of each protein was scored as predominantly nuclear (N or N >C) or mostly cytoplasmic (C or C>N).