Atherosclerosis 181 (2005) 39–44 Basic Research Mouse cytomegalovirus antigenic immune stimulation is sufficient to aggravate atherosclerosis in hypercholesterolemic mice Inge Vliegen ∗ , Selma B. Herngreen, Gert E.L.M. Grauls, Cathrien A. Bruggeman, Frank R.M. Stassen Department of Medical Microbiology, Cardiovascular Research Institute Maastricht, Maastricht University, P.O. Box 5800, 6202 AZ Maastricht, The Netherlands Received 5 July 2004; received in revised form 18 November 2004; accepted 16 December 2004 Available online 5 February 2005 Abstract We have previously demonstrated that mouse cytomegalovirus (MCMV) infection aggravates atherosclerosis by stimulating the ongoing inflammatory process in the vascular wall. Here we investigated whether MCMV antigenic immune stimulation by UV-MCMV injection is sufficient to aggravate atherosclerosis. In addition we analyzed whether low viral doses are sufficient to stimulate atherosclerosis. Therefore, apoE -/- mice received a low dose injection with infectious virus (MCMV) or replication-deficient virus (UV-inactivated MCMV, UV-MCMV). Atherosclerosis progression, influx of inflammatory cells in atherosclerotic lesions and internal organs and the number of MCMV DNA copies in various organs were determined at 2 weeks after injection. After injection with infectious virus, MCMV DNA was present in internal organs, while no MCMV DNA could be detected after UV-MCMV injection. Interestingly, both MCMV and UV-MCMV significantly increased mean atherosclerotic lesion area and T cell number in the atherosclerotic lesions, while only MCMV infection increased T cell numbers in the internal organs. These data indicate that in apoE -/- mice both low dose infectious MCMV as well as MCMV antigenic injections are sufficient for atherosclerosis aggravation. © 2005 Elsevier Ireland Ltd. All rights reserved. Keywords: Atherosclerosis; Immunology; Infection/inflammation; Mouse; CMV 1. Introduction Since the late 1970s, when Fabricant et al. [1] established that chickens infected with an avian herpes virus (Marek disease virus) develop an atherosclerosis-like disease, evi- dence linking atherosclerosis to infections is accumulating. Currently a clear association between a diversity of infec- tions (including cytomegalovirus) and the progression of the atherosclerotic process has been demonstrated [2]. Cytomegalovirus (CMV) is a member of the -herpes sub- family of the herpes virus group. In the immunocompetent host primary infection causes a lifelong asymptomatic latent infection with intermittent shedding of the virus. On the other ∗ Corresponding author. Tel.: +31 43 387 66 44; fax: +31 43 387 66 43. E-mail address: ivl@lmib.azm.nl (I. Vliegen). hand, immuno-compromised patients infected with CMV are at risk of developing severe to lethal diseases like retinitis, colitis and hepatitis depending on the extent of immuno- suppression. Several epidemiological reports indicate that chronic CMV infection in humans may play an important role in the pathogenesis of vascular diseases such as atheroscle- rosis or restenosis [3]. Furthermore, the presence of the virus in atherosclerotic lesions indicates that CMV is a possible primary etiologic factor or a co-factor in the atherosclerotic process [4,5]. To study the contribution of CMV to the atherosclerotic process, well-controlled in vivo experiments in animals are a necessity. Since atherosclerotic lesions in apoE -/- mice dis- play a high similarity with human atherosclerotic lesions with respect to distribution and cellular composition [6,7], this mouse model is particularly suitable for studying genetic and 0021-9150/$ – see front matter © 2005 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.atherosclerosis.2004.12.035