Fig. 5 |. Mechanisms of neutralization of human norovirus by antibodies.
a, Neutralization of GI.1 by the human antibody 5I2 (yellow) by directly competing with the histoblood group antigen (HBGA) binding site in the protruding (P) domain dimer (grey). b, Neutralization of GI.1 by the human antibody 10E9 (purple) by directly competing with the HBGA binding site in the P domain dimer (grey). c, Human antibody A1431 (blue) binds to an epitope slightly away from the HBGA binding site in the GII.4 P domain dimer (grey) and neutralizes GII.4 by clumping or crosslinking particles. d, Resting and raised conformations of the P domain (shell (S), P1, and P2 subdomains are shown in blue, red, and yellow, respectively). e, Fragment antigen-binding region (Fab) of the human antibody NORO-320 (yellow) targets capsid plasticity by binding an epitope in the GII.4 P domain (grey) that is exposed only in the raised conformation and probably neutralizes the virus by blocking co-receptor interactions or VP2 externalization. f, The llama nanobody M4 (green) also binds to an epitope exposed only when the P domain (grey) transits to the raised confirmation and neutralizes by compromising capsid integrity.