ST3GAL3-mediated selective α2,3-sialylation of LDLR promotes vesicular stomatitis virus entry

Vesicular stomatitis virus (VSV) is a model rhabdovirus whose infectivity is determined primarily by its envelope glycoprotein (VSV-G). The low-density lipoprotein receptor (LDLR), a cell-surface glycoprotein, has been identified as the major receptor for VSV-G binding. However, the role of host sialylation in VSV-G-dependent entry remains poorly understood.

Viral association, uptake, and transduction were evaluated in HeLa cells lacking β-galactoside α2,3-sialyltransferase 3 (ST3GAL3), 4 (ST3GAL4), or 6 (ST3GAL6) using flow cytometry, fluorescence microscopy, and Western blotting. LDLR sialylation was analyzed by lectin binding and LC-MS/MS glycoproteomics of recombinant soluble LDLR.

ST3GAL3 knockout (KO) significantly reduced viral association, uptake, and transduction, and this effect was reversed by re-expression of ST3GAL3. Loss of ST3GAL3 decreased α2,3-linked sialylation of endogenous LDLR N-glycans, as indicated by Maackia amurensis lectin binding. Consistent with these findings, LC-MS/MS analysis revealed site-specific decreases in sialylated glycoforms of recombinant LDLR.

ST3GAL3-dependent sialylation of LDLR N-glycans is required for efficient viral entry and is not compensated by ST3GAL4 or ST3GAL6 in HeLa cells.

These findings identify a specific glycosylation pathway essential for VSV-G-dependent infection and suggest ST3GAL3 as a potential target to modulate viral tropism, with implications for oncolytic VSV strategies.