The role of viral genomic RNA and nucleocapsid protein in the autophagic clearance of hantavirus glycoprotein Gn.

Hantaviruses have tri-segmented negative sense RNA genome. The viral M-segment RNA encodes a glycoprotein precursor (GPC), which is cleaved into two glycoprotein molecules Gn and Gc that form spikes on the viral envelope. We previously reported that Gn is degraded shortly after synthesis by the host autophagy machinery. However, Gn being an important integral component of the virion, must escape degradation during the packaging and assembly stage of virus replication cycle. The mechanism regulating the intrinsic steady-state levels of Gn during the course of virus replication cycle is not clear. We transfected cells with plasmids expressing viral S-segment RNA, nucleocapsid protein and glycoproteins Gn and Gc and monitored their expression levels over time. These studies revealed that accumulation of nucleocapsid protein, glycoprotein Gc and viral S-segment RNA helped to stabilize Gn. These observations suggest that initiation of virus assembly may help Gn to escape autophagic degradation by yet unknown mechanism.