HSV-1 nucleocapsid egress mediated by UL31 in association with UL34 is impeded by cellular transmembrane protein 140

- Cellular TMEM140 protein interacts with HSV-1 UL31 protein during viral infection.
- Increasing expression of TMEM140 leads to inhibition of HSV-1 proliferation.
- Increasing expression of TMEM140 blocks HSV-1 nucleocapsid egress process.
- Binding to UL31 of TMEM140 impedes formation of HSV-1 UL31-UL34 complex.

During HSV-1 infection, the viral UL31 protein forms a complex with the UL34 protein at the cellular nuclear membrane, where both proteins play important roles in the envelopment of viral nucleocapsids and their egress into the cytoplasm. To characterize the mechanism of HSV-1 nucleocapsid egress, we screened host proteins to identify proteins that interacted with UL31 via yeast two-hybrid analysis. Transmembrane protein 140 (TMEM140), was identified and confirmed to bind to and co-localize with UL31 during viral infection. Further studies indicated that TMEM140 inhibits HSV-1 proliferation through selectively blocking viral nucleocapsid egress during the viral assembly process. The blockage function of TMEM140 is mediated by impeding the formation of the UL31-UL34 complex due to competitive binding to UL31. Collectively, these data suggest the essentiality of the UL31-UL34 interaction in the viral nucleocapsid egress process and provide a new anti-HSV-1 strategy in viral assembly process of nucleocapsid egress.