Abstract
SummaryImmunoglobulin A (IgA) plays an important role in protecting our mucosal surfaces from viral infection, in maintaining a balance with the commensal bacterial flora, and in extending maternal immunity via breast feeding. Here, we report an additional innate immune effector function of human IgA molecules in that we demonstrate that the C-terminal tail unique to IgA molecules interferes with cell-surface attachment of influenza A and other enveloped viruses that use sialic acid as a receptor. This antiviral activity is mediated by sialic acid found in the complex N-linked glycans at position 459. Antiviral activity was observed even in the absence of classical antibody binding via the antigen binding sites. Our data, therefore, show that the C-terminal tail of IgA subtypes provides an innate line of defense against viruses that use sialic acid as a receptor and the role of neuraminidases present on these virions.
Highlights
Vaccination against influenza A viruses relies on the induction of strain-specific neutralizing immunoglobulin G (IgG) and has to be repeated annually
We report an additional innate immune effector function of human Immunoglobulin A (IgA) molecules in that we demonstrate that the C-terminal tail unique to IgA molecules interferes with cell-surface attachment of influenza A and other enveloped viruses that use sialic acid as a receptor
This antiviral activity is mediated by sialic acid found in the complex N-linked glycans at position 459
Summary
Vertebrate IgA molecules possess a conserved N-linked glycosylated C-terminal tail. Maurer et al show that sialic acid found in the complex glycosylation of the C-terminal tail of human IgA1 inhibits sialic-acid-binding viruses and, may constitute an additional line of innate immunity. Highlights d Heterosubtypic IgA1 or IgA2 antibodies neutralize virus much more potently than IgG1 d Sialic acid in IgA’s C-terminal tail competes with viral receptor binding d This may represent an innate line of defense against viral pathogens.
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