Fig 1: Confirmation of targeting proficiency for mC3 and mFc ligands via immunofluorescence assay (IFA). (A) Illustration of the ligands-receptors interactions that were demonstrated by IFA. Following mRNA transfection into 293T cells, receptors were incubated with the cells. Then, RBD-mC3 bound CR1 while RBD-mFc bound FcγR. The RBD-mC3 and RBD-mFc were labeled by anti-RBD monoclonal antibodies. The CR1 and FcγR were marked using anti-CR1 polyclonal antibodies and anti-FcγR monoclonal antibodies, respectively. (B) Antibodies targeting CR1 (FITC, green) and RBD-mC3 (Cy5, purple) depicted the respective distributions of CR1 and RBD-mC3. (C) Colocalization analysis of RBD-mC3 and CR1. (D) Antibodies against FcγR (green) and RBD-mFc (purple) showed the distributions of FcγR and RBD-mFc respectively. The blue color (DAPI) represented the cell nuclei. (E) Colocalization analysis of RBD-mFc and FcγR. Three regions of interest (ROI) were analyzed. Pearson’s coefficient (R) was calculated in colocalization analysis. R > 0.8 suggests a very strong correlation.