Session: Session 5

YXXL/YXX MOTIFS WITHIN gE CT DOMAIN REGULATES gE PROTEIN INTRACELLULAR TRAFFICKING AND BHV-1 VIRUS SPREAD

Introduction

Bovine Herpes Virus-1 (BHV-1) is a major pathogen of cattle. The primary infection by BHV-1 in the cattle is characterized by establishment of latency in trigeminal ganglia (TG) within central nervous system. Upon reactivation by stress factors, the virus is transported from neuronal cell bodies in the TG to projected nerve endings in nose and cornea of latently infected cattle where the virus shedding occurs. The glycoprotein BHV-1 gE is considered as a multifunctional envelope protein important for virulence, in vitro cell to cell spread and trans-neuronal anterograde transport.

Methodology

The BHV-1 gE-CT region has several potential tyrosine-based phosphorylation motifs (YXXL), cellular sorting motifs (YXXΦ) and an acidic domain containing several Serine phosphorylation sites. To investigate the role of each of these gE trafficking signals in gE functions, endocytosis, gE trans Golgi network redistribution at early phases of virus infection, gE virion incorporation and basolateral surface localization, a panel of gE CT specific mutant viruses were constructed and analyzed. In MDBK infected cells.

Results

We have found that disruption of ₄₆₇YTSL₄₇₀ motif abolished trans-Golgi network redistribution and basolateral cell surface localization of gE with a defective gE protein virion incorporation. While the disruption of ₅₆₃YTVV₅₆₆ has a defective basolateral cell surface localization. Interestingly, we found that Y467 residue showed a phosphorylated statue but not Y563 residue. Both Y467A and Y563A mutant viruses exhibit cell-to-cell spread defect characterized by smaller plaque size formation.

Conclusion

These results support a role for ₄₆₇YXXL and ₅₆₃YXXΦ gE-CT motifs in gE subcellular trafficking and are directly involved in the regulation of efficient virus epithelial cell to cell spread.