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Journal of Virology, November 2001, p. 10721-10729, Vol. 75, No. 22
Department of Molecular Microbiology and
Immunology, Saint Louis University School of Medicine, St. Louis,
Missouri 63104,1 and Departments of
Ophthalmology and Visual Sciences2
and Molecular Microbiology,3 Washington
University School of Medicine, St. Louis, Missouri 63110
Received 6 June 2001/Accepted 9 August 2001
The VP22 protein of herpes simplex virus type 2 (HSV-2) is a major
component of the virion tegument. Previous work with HSV-1 indicated
that VP22 is phosphorylated during infection, and phosphorylation may
play a role in modulating VP22 localization in infected cells. It is
not clear, however, when phosphorylation occurs in infected cells or
how it is regulated. Less is known about the synthesis and
phosphorylation of HSV-2 VP22. To study the complete biosynthetic history of HSV-2 VP22, we generated a monoclonal antibody to the carboxy terminus of VP22. Using immunoprecipitation and Western blot
analyses, we show that HSV-2 VP22 can be found in three distinct isoforms in infected cells, two of which are phosphorylated. Like HSV-1
VP22, HSV-2 VP22 is synthesized ca. 4 h after infection, and the
isoform later incorporated into virions is hypophosphorylated. In
addition, we demonstrate for the first time (i) that newly synthesized
VP22 is phosphorylated rapidly after synthesis, (ii) that this
phosphorylation occurs in a virus-dependent manner, (iii) that the
HSV-2 kinase UL13 is capable of inducing phosphorylation of VP22 in the
absence of other viral proteins, (iv) that phosphorylated VP22 is very
stable in infected cells, (v) that phosphorylated isoforms of VP22 are
gradually dephosphorylated late in infection to produce the virion
tegument form, and (vi) that this dephosphorylation occurs
independently of viral DNA replication or virion assembly. These
results indicate that HSV-2 VP22 is a stable protein that undergoes
highly regulated, virus-dependent phosphorylation events in infected cells.
0022-538X/01/$04.00+0 DOI: 10.1128/JVI.75.22.10721-10729.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Temporal Regulation of Herpes Simplex Virus Type 2 VP22 Expression and Phosphorylation
*
Corresponding author. Mailing address: Department of
Molecular Microbiology and Immunology, Saint Louis University School of
Medicine, 1402 S. Grand Blvd., St. Louis, MO 63104. Phone: (314)
577-8321. Fax: (314) 773-3403. E-mail: morrisla{at}slu.edu.
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