Könighofer et al.
Identification of three novel O-linked glycans in the envelope protein of tick-borne encephalitis virus. Preprints. 2024, doi:10.20944/preprints202410.0914.v1
Glycoprotein E (gE) of the TBE virus contains a single N-glycan linked at N154, and this glycan has been connected to important functions in viral entry, infectivity, and pathogenesis of TBE virus. In addition to the N-linked glycan, gE contains 67 potential O-linked glycosylation sites, but there are so far no reported data showing O-linked glycosylation of gE.
However, three O-linked glycans have recently been identified in the gE of a clinical TBE virus isolate (designated F7203), which was obtained from a Swedish patient and propagated in the human adenocarcinomic cell line A549. Analysis of 762 TBE virus strains from the European, Siberian, and Far Eastern subtypes revealed a high degree of conservation in the amino acid sequences surrounding the potential carriers of these O-linked structures. Notably, one O-linked glycan is located near the highly conserved N-linked glycan at N154, suggesting a potential role in viral maturation.
In addition, the N-linked glycan at position N154 was structurally analyzed.
The predominant structure identified was the oligomannose form, Man6GlcNac2, though a substantial fraction carried 8 to 9 mannose residues. Complex N-linked glycan structures were also detected, primarily with the composition HexNac4Hex5Fuc1. Only 5% of the N-linked glycans contained one or more sialic acid residues.
Glycosylation can influence antigen processing and presentation of antigen-presenting cells. Inactivated TBE vaccines produced on chick embryo fibroblasts (e.g. FSME Immun and Encepur) exhibit the glycosylation profile specific to these cells. Newly developed recombinant TBE vaccines may possess a modified glycosylation pattern dependent on the host cell used for virus production and may have an altered immunogenicity.