BRIEF REPORT HSV-2 ICP34.5 protein modulates herpes simplex virus glycoprotein processing Somik Chatterjee Æ Jason W. Wang Æ Mary J. Cismowski Æ John R. Bower Æ Kenneth Steven Rosenthal Received: 4 December 2008 / Accepted: 17 February 2009 / Published online: 7 March 2009 Ó Springer-Verlag 2009 Abstract The ICP34.5 gene from HSV-2 strain 333 was cloned and, when expressed in Vero cells, enhanced the efficiency and extent of glycoprotein processing of glyco- protein C (gC1), a representative viral glycoprotein, during infection with HSV-1 SP7. The ICP34.5 from HSV-1 SP7 limits the extent and efficiency of viral glycoprotein pro- cessing. The ability of the HSV-2 ICP34.5 protein to enhance the efficiency and extent of HSV-1 SP7 glyco- protein processing indicates that modulation of viral glycoprotein processing is also a property of the HSV-2 ICP34.5 protein. ICP34.5 (infected cell protein 34.5) of herpes simplex virus (HSV) is a multifunctional protein that is essential for replication of the virus in neuronal and non-growing cells [1–3]. Mutations within the gene can affect the ability of the virus to cause encephalitis in mouse models [4–6]. In addition, HSV-1 strain-dependent, structurally different variants of ICP34.5 also differ in their influence on the tissue culture behavior and the extent and efficiency of glycoprotein processing [6]. Comparatively little is known about the functions of HSV-2 variants of ICP34.5. The ICP34.5 gene is encoded in both of the inverted repeats of the unique long sequence of the HSV genome [7] and is expressed as a leaky late protein. The HSV-1 protein has three regions, an N-terminal arginine-rich region, a central region with a strain-dependent variable number of proline–alanine–threonine (PAT) repeats, and a conserved C-terminal region that shares sequence homology with the mammalian growth arrest and DNA damage 34 (GADD34) protein [8, 9]. The GADD34-like region is capable of binding to protein phosphatase 1. The HSV-1 ICP34.5 also contains beclin 1 [4] and TANK-binding kinase 1 [10] binding domains that precede the PAT repeat region. There is extensive homology in the ICP34.5 sequences of HSV-1 strains and some homology with the prototype HSV-2 HG52 (GenBank accession number NC_001798) and HSV-2 333 (GenBank accession number DQ149924) sequences, especially at the C-terminus. The most signifi- cant difference between the ICP34.5 genes from HSV-1 and HSV-2 is at their center, where the region encoding a repeat sequence for HSV-1 is within an intron, resulting in an HSV-2 protein that lacks PAT repeats [11]. ICP34.5 from HSV-1 has been shown to modulate the efficiency and extent of viral glycoprotein processing and virus release using in vitro complementation experiments and recombinant viruses [5, 6]. The ICP34.5 from the neuroinvasive, small-plaque-producing SP7 strain [5, 6] would limit the extent and efficiency of glycoprotein processing, while the ICP34.5 variants from KOS321 or SLP10 strains would allow or promote their processing [5, 6]. In this study, we asked whether the ICP34.5 from HSV-2 influences viral glycoprotein processing, as does its analogue for HSV-1. We demonstrated that the HSV-2 strain 333 variant of the ICP34.5 protein can override the S. Chatterjee Á J. W. Wang Á J. R. Bower Á K. S. Rosenthal (&) Integrative Medical Sciences, Northeastern Ohio Universities Colleges of Medicine and Pharmacy, Rootstown, OH 44272, USA e-mail: ksr@neoucom.edu M. J. Cismowski Children’s Research Institute, Nationwide Children’s Hospital, Columbus, OH 43205, USA J. R. Bower Akron Children’s Hospital Medical Center, Akron, OH 44308, USA 123 Arch Virol (2009) 154:661–663 DOI 10.1007/s00705-009-0341-9