Journal: Cell reports
Article Title: Selective decoupling of IgG1 binding to viral Fc receptors restores antibody-mediated NK cell activation against HCMV
doi: 10.1016/j.celrep.2025.116593
Figure Lengend Snippet: (A) Binding of host Fc receptors (FLAG-tagged CD16A-GST, FcRn-GST, or gp34-M) to immobilized human Fc was measured in the presence of competitor (gp34-M, t-gp68, and hu-Fc) by ELISA. Assay area under the curve (AUC) was normalized to controls lacking a competitor and presented as a heatmap. (B and C) Binding of antibody Fc variants to gp34-M, t-gp68, and (B) FcRn or (C) CD16A assessed by ELISA with normalized inverse 50% effective concentration (EC 50 ) values shown as a heatmap with more color indicating better binding. (D and E) The nsEM 3D reconstruction and 2D class averages for particles containing (D) one Fc with one gp34-M bound near the CH 2 tip and (E) one Fc with one t-gp68 bound to the CH 2 -CH 3 interface. RoseTTAFold-based gp34 (green) and t-gp68 (blue) models fit the 3D reconstruction with the Fc crystal structure (PDB: 2GJ7). Scale bars, 5 nm. (F and G) SPR measured (F) t-gp68 binding to immobilized Fc and (G) binding of human IgG1 antibody to immobilized gp34-M with K D values determined using BIAevaluation X100 software. (H and I) Flow cytometry measured (H) binding to and (I) internalization of pHrodo-Red-labeled antibody (67 nM) by AD169-infected MRC5 cells (MOI = 2 and 96 hpi) in the presence of t-gp68 (2 μM) and/or gp34-M (0.1 μM). Extracellular antibody detected with goat-anti-human-Fcy AF647; in (I), the dashed line represents the threshold for detection. Data shown are mean ± SD, n = 2, with * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001, and ns, non-significant. All analyses are performed in GraphPad using two-way ANOVA with Tukey’s multiple comparisons test. Representative data of one experiment is shown; each experiment is repeated at least twice.
Article Snippet: Bound hu4D5 antibodies were detected by incubation with goat anti-human kappa light chain antibody-HRP (Southern Biotech Cat #2060–05, 1:2000 dilution).
Techniques: Binding Assay, Enzyme-linked Immunosorbent Assay, Concentration Assay, Software, Flow Cytometry, Labeling, Infection