Involvement of gD/HVEM interaction in NF-kB-dependent inhibition of apoptosis by HSV-1 gD Maria Teresa Sciortino a , Maria Antonietta Medici a , Francesca Marino-Merlo a , Daniela Zaccaria a , Maria Giuffre `-Cuculletto a , Assunta Venuti a , Sandro Grelli b , Placido Bramanti c , Antonio Mastino a,c, * a Department of Life Sciences, Section of Microbiological, Genetic and Molecular Sciences, University of Messina, Salita Sperone 31, 98166 Messina, Italy b Department of Experimental Medicine and Biochemical Sciences, University of Rome ‘‘Tor Vergata’’, Rome, Italy c IRCCS Centro Neurolesi ‘‘Bonino-Pulejo’’, Messina, Italy 1. Introduction Replication and spread of viruses can be efficiently limited by a cellular apoptotic response, that represents an important, first line form of antiviral innate defense (reviewed in [1–3]). 1 Nevertheless, different viruses have evolved multiple survival strategies to escape elimination by apoptosis and interference with signals involved in the death of infected cells is one of the biochemical pharmacology 76 (2008) 1522–1532 article info Article history: Received 17 May 2008 Accepted 24 July 2008 Keywords: HSV-1 Apoptosis Glycoprotein D HVEM Viral evasion abstract In the present paper, we aimed to verify whether the interaction of the glycoprotein D (gD) of herpes simplex 1 (HSV-1) with the HSV-1 receptor HVEM is involved in NF-kB-dependent protection against apoptosis by gD. To this purpose, first we utilized MAbs that interfere with gD/HVEM interaction and U937 cells that naturally express human HVEM on their surface. Pre-incubation with these MAbs, but not with a control antibody, partially reverted the protection of infectious HSV-1 towards anti-Fas induced apoptosis in U937 cells. Similarly, pre-incubation of UV-inactivated HSV-1 (UV-HSV-1) or recombinant gD with the same MAbs, significantly reduced the inhibition of Fas-mediated apoptosis by UV- HSV-1 or gD, respectively, in U937 cells. Moreover, coculture with stable transfectants expressing at surface level wild type gD protected U937 cells against Fas-induced apoptosis, while coculture with transfectants expressing a mutated form of gD, incapable to bind HVEM, did not protect. Finally, UV-HSV-1 protected against staurosporine-induced apop- tosis in U937 cells as well as in the CHO transfectants expressing human HVEM on their surface, but not in the control CHO transfectants, which did not express HVEM. These results suggest that signaling triggered by binding of gD to HVEM could represent an additional mechanism of evasion from premature apoptotic death exerted by HSV-1-gD in HVEM-expressing cells, disclosing new opportunities of cell death manipulation by using gD preparations. # 2008 Elsevier Inc. All rights reserved. * Corresponding author at: Department of Life Sciences, Section of Microbiology, Genetics and Molecular Biology, University of Messina, Salita Sperone 31, 98166 Messina, Italy. Tel.: +39 090 6765193; fax: +39 090 392733. E-mail address: antonio.mastino@unime.it (A. Mastino). 1 This paper was presented in part in the form of a poster at the meeting ‘‘Apoptosis World 2008: From mechanisms to applications’’, Luxembourg, 23–26 January 2008. available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/biochempharm 0006-2952/$ – see front matter # 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.bcp.2008.07.030