FIG. 4.

Expression of the NDV V protein prevents transfection-induced inhibition of NDV-GFP replication. (A) Diagram of the four NDV P and V constructs used. The gray boxes on the left indicate shared amino-terminal domains. The V protein possesses a cysteine-rich carboxy-terminal region distinct from the P protein. This V-specific domain arises due to the insertion of a single non-template-encoded G residue and is indicated by the hatched box. V_N possesses only the shared amino-terminal region. V_C possesses the V carboxy terminus to which an initiator ATG has been added. (B) GFP expression in NDV-GFP-infected cells transfected 24 h prior to infection with NDV P, NDV V, NDV V_N, or NDV V_C expression plasmids. (C) Relative mean green fluorescence of CEFs transfected with empty vector (pCAGGS) or transfected with NDV P, NDV V, NDV V_N, or NDV V_C expression plasmids as indicated and subsequently infected with NDV-GFP. Shown is the relative mean intensity of green fluorescence for 10⁴ cells from each culture as determined by FACS. The results from panels B and C are from the same experiment and are representative of typical results with the indicated plasmids.