CALR-dependent endoplasmic reticulum N-glycoprotein maturation promotes Japanese encephalitis virus entry and...

The endoplasmic reticulum (ER) chaperone machinery participates in multiple stages of viral infection, from entry through assembly and release. However, how ER-resident quality-control mechanisms shape cellular permissiveness to Japanese encephalitis virus (JEV) remains unclear. Here, we identify the ER-resident chaperone calreticulin (CALR) as a key host factor that promotes cellular permissiveness to JEV infection. CRISPR/Cas9-mediated knockout of CALR markedly reduces JEV attachment, internalization, and productive replication. Mechanistically, CALR depletion disrupts N-linked glycosylation homeostasis and selectively reduces the abundance of the integrin subunit ITGA3 through an ER glycan-dependent maturation checkpoint. Glycomic analysis revealed accumulation of immature N-glycan precursors, indicating compromised N-glycoprotein maturation. In parallel, CALR deficiency markedly reduced the abundance of the viral envelope (E) glycoprotein, suggesting that CALR plays a dual role in shaping host permissiveness and supporting viral glycoprotein biogenesis. Together, these results identify CALR as a central regulator of a replication-permissive ER glycoprotein maturation state that supports both ITGA3-associated cellular adhesion and efficient viral E protein biogenesis, thereby supporting JEV replication. Our findings highlight the calnexin/calreticulin (CANX/CALR)-dependent N-glycosylation axis as a potential host-directed target for antiviral strategies.