Fig 4.

Chimeric proteins containing the MV H stalk domain and the NDV globular head activate MV F. (A) Schematic structures of MV H _HIS and H_1–160 HN_{124–571 HIS}. (B) FACS analysis results for cell surface expression. Cells were transfected with the MV H _HIS and H_1–160 HN1_{24–571 HIS} proteins and analyzed for cell surface expression by using anti-histidine antibodies. The values are means (with SD) for results from triplicate samples and are representative of an experiment repeated at least four times. (C to F) Cell-to-cell fusion of 293T cells bearing chimeric proteins with anti-histidine antibody-expressing target cells (Vero-His) transfected with the MV receptor CD150 (C and E) or empty vector (D and F). Cell-to-cell fusion was measured in the presence (E and F) or absence (C and D) of neuraminidase by a β-Gal complementation assay as described in Materials and Methods. The values are means (with SD) for results from triplicate samples of a representative experiment repeated at least three times. *, P < 0.05; ns, not significant (Mann-Whitney test).