Figure 1: Retargeting the wild type CDV Hemagglutinin (H) protein to EGFR and CD38.

A) Schematic representation of retargeted CDV H protein constructs (not drawn to scale). Standard one-letter amino acid abbreviations are used to denote the mutations that ablate the use of the native receptors (dogSLAM and NECTIN4) thereby generating receptor blind CDV H (CDV H_RB). The single-chain antibody fragment (scFv) and a six-histidine tag (6xHis) is displayed as a C-terminal extension of H with a flexible linker containing the Factor Xa, Fxa, (IEGR) cleavage site. (B) Immunoblot analysis of HEK293 cell lysates after transient transfection of engineered CDV H expression plasmids (CDV H, CDV H-CD38, CDV H_RB-CD38, CDV H_RBEGFR) using an antibody directed against the cytoplasmic tail of CDV H. C) Co-transfection experiments evaluating receptor-specific intercellular fusion mediated by engineered CDV H and CDV F glycoproteins. CHO Cells expressing the desired receptors were co-transfected with a CDV F expression plasmid and the respective engineered CDV H expression plasmids, stained with crystal violet 48 hours post transfection and imaged (100X magnification). (D) Impact of pooled measles immune human serum on Intercellular fusion mediated by retargeted CDV envelope. CHO-CD38 cells were either co-transfected with the CDVH_RB-CD38 and CDV F or the homologous MV Haals-CD38 and MV F expression plasmids, and a GFP expression plasmid for visualization of fusion, and incubated with the indicated dilutions (made with culture medium) of pooled human serum (PRN = 256; anti-MV IgG titer = 300 EU/mL). Photographs were taken at 48 hours post transfection under a fluorescence microscope. 100X magnification