Fig. 4: Biophysical and structural characterization of broadly neutralizing antibody 441D6.
From: Mosaic nanoparticle display of diverse influenza virus hemagglutinins elicits broad B cell responses
a, Binding kinetics of 441D6 Fab to NY96 hemagglutinin, determined by biolayer interferometry. Measured sensorgram and calculated curve fit (1:1 binding model) are shown in red and black, respectively. Experiments were independently performed twice with similar results. b, Summary of binding affinities (KD) of 441D6 Fab to a diverse set of 12 H1N1 hemagglutinins. Each HA–Fab interaction was plotted and color-coded on the basis of year of identification of the virus. Binding kinetics details are found in Supplementary Fig. 4. c, 2.0-Å crystal structure of unliganded 441D6 Fab. Somatic mutations of 441D6 Fab (right). Residues that underwent SHM are colored blue. Amino acid sequence of CDRH1–3 and CDRL1–3 loops are shown with SHM residues in blue. HC, heavy chain; LC, light chain. d, Cryo-electron microscopy structure of NY96 hemagglutinin trimer in complex with 441D6 Fab. Side view along the longitudinal axis of an hemagglutinin trimer (top) and top view looking down on the three-fold axis of an hemagglutinin trimer from the membrane distal end (bottom) are shown. Superimposition of NY96 hemagglutinin (homology model, gray) and 441D6 Fab (orange-red) coordinates into the cryo-electron microscopy density map (right). White asterisks indicate sialic acid–binding pocket on each hemagglutinin protomer. e, Updated antigenic sites of H1N1 hemagglutinin. Known antigenic sites Sa, Sb, Ca1, Ca2 and Cb are shown, along with the site recognized by 441D6. f, Surface conservation of 1,368 non-overlapping H1N1 hemagglutinins. Conservation scores were calculated by the ConSurf server (http://consurf.tau.ac.il) and were colored on one NY96 hemagglutinin protomer with dark blue equating to highest conservation. g,h, Predicted 441D6 epitope (colored) mapped on NY96 hemagglutinin (g) and paratope of 441D6 (h). Each paratope residue is colored according to buried surface area (BSA) contribution. i, Amino acid sequence of HA1 subunit of NY96 hemagglutinin. 441D6 epitope residues are indicated by conservation score and BSA.
