Figure 2 - Mechanisms of viral neutralization.

(a) Antibodies block receptor engagement by binding to spikes on an enveloped virus. (b) Antibody blocks virus entry by binding to a viral cellular receptor (or coreceptor) on cell surface. (c) Post-binding/pre-fusion neutralization occurring inside endosome. For some viruses, conformational changes in viral proteins required for fusion are triggered by the low pH in the endosome. MAbs that block the requisite interactions between viral and endosomal membrane proteins would delay or prevent the penetration of the viral core into the target-cell cytoplasm. (d) Post-binding/pre-fusion neutralization occurring at the cell membrane. Antibodies binding to non-receptor binding regions of the viral envelope can neutralize viral infection through interfering with conformational changes that are required for membrane fusion. (e) Inhibition of the release of progeny virus. For example, mAbs to influenza A virion surface neuraminidase prevent the release of virions from the infected cell surface. Not shown in the figure are neutralizing effects of antibodies on the virus before cell binding, which include antibody-mediated virus aggregation to reduce the number of infectious particles.

Katie Ris-Vicari