Egg-derived glycan epitopes on influenza virion proteins

Egg-derived glycan epitopes are specific carbohydrate structures, most notably sulfated N-acetyllactosamine (LacNAc), that are added to influenza virus proteins such as hemagglutinin (HA) and neuraminidase (NA) when the virus is propagated in embryonated chicken eggs for vaccine production. These glycans are distinct from those found on viruses grown in mammalian cells or circulating in the human population, leading to a phenomenon known as egg adaptation. In the context of influenza vaccines, these egg-specific glycans act as antigenic decoys, diverting the host's immune response away from protective viral epitopes and toward non-neutralizing glycan targets. This diversion can significantly reduce vaccine effectiveness and contribute to antigenic mismatch between the vaccine strain and circulating viruses, particularly for H3N2 subtypes. Furthermore, these epitopes are a primary concern for individuals with egg allergies, as they can be recognized by IgE antibodies and trigger hypersensitivity reactions. Recent research focuses on modifying vaccine production, such as using cell-based or recombinant platforms, to avoid these egg-derived modifications and improve the breadth and potency of the immune response.

Other names

Egg-adapted glycansEgg-specific glycosylationSulfated N-acetyllactosamine (LacNAc) epitopesEgg-derived antigenic decoysEgg-associated glycans