CHARACTERIZATION OF THE COMPLEX FORMED BY THE VARICELLA ZOSTER VIRUS ORF9P AND THE CELLULAR ADAPTIN PROTEIN-1 AND ITS ROLE IN THE SECONDARY EGRESS

ORF9p (homologous to HSV-1 VP22) is a VZV tegument protein essential for the viral
replication. We have shown that ORF9p co-immunoprecipitates with the clathrine Adaptor
Protein-1 (AP-1) complex and have identified the leucine at position 231 as important for this
interaction. The mutation of this residue strongly impairs the virus replication in MRC-5 cells.
We have also demonstrated that the essential glycoprotein gE interacts with the AP-1
complex in an ORF9p independent manner. We are therefore seeking to determine the role
of ORF9p in the complex formation and the role of this complex in VZV secondary
envelopment and egress.
Furthermore, we have shown that the deletion of the 32 amino-terminal residues impairs the
interaction between ORF9p and the AP-1 complex and impacts the secondary envelopment.
This region contains a glycine and a cysteine predicted to be potentially myristoylated or
palmitoylated respectively. These modifications could serve to anchor ORF9p in the
membrane network where it could interact with the AP-1 complex. We are investigating this
possibility using mass spectrometry.