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Figure 3 | Retrovirology

Figure 3

From: Are anti-HIV IgAs good guys or bad guys?

Figure 3

IgA-mediated protection against HIV/SHIV at mucosal surfaces. A. Passive immunization with a neutralizing monoclonal dIgA. After topical administration of the neutralizing mAb in the mucosal lumen of macaques, dIgAs bind to SHIV and prevent virions from crossing the epithelial barrier by forming large SHIV-dIgA complexes. Reports from the literature describe the presence of free SC in various mucosal fluids [27]-[29]. B and C. Protection by locally produced IgA in HEPS individuals or induced by vaccination. B. Immune exclusion; inhibition of transcytosis. HIV/SHIV-specific dIgA is produced by mature plasma cells in the lamina propria and interacts with pIgR (in blue) on the basolateral surface of epithelial cells; export of dIgA across the epithelial cells is mediated by pIgR. The latter undergoes proteolytic cleavage at the luminal side, which results in the generation of SC that is retained by dIgA molecules, releasing SIgA into the lumen. SIgA binds to SHIV and prevents viral invasion of epithelial cells by forming large SHIV-dIgA complexes. C. Intracellular neutralization. After the dIgA-pIgR complex is formed intracellularly, HIV/SHIV particles that have invaded the epithelial cells are bound and then excreted as virion-dIgA-pIgR complex. This returns the SIgA-virion complex into the mucosal lumen.

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