Molecular study of human herpesvirus 6 and 8 involvement in coronary atherosclerosis and coronary instability.

Several lines of evidence suggest the involvement of infectious agents in the pathogenesis of atherosclerosis. Furthermore, a correlation between infection-driven inflammatory burden and acute manifestation of coronary artery disease has been hypothesized. The aim of this work was to assess whether human herpesvirus (HHV)-6 and HHV-8, two DNA viruses with a distinct tropism for endothelium and lymphocytes, may be associated with coronary instability. An age- and gender-matched cross-sectional study was undertaken in 70 patients with testing of plasma HHV-6 and HHV-8 DNA load in different cardiovascular clinical settings: 29 patients with acute myocardial infarction, 21 patients with stable coronary artery disease, and 20 patients without coronary and carotid artery atherosclerosis subjected to cardiac valve replacement. In all patients, HHV-6 and HHV-8 plasma DNA was tested by using highly sensitive, calibrated quantitative real-time PCR assays which employ a synthetic DNA calibrator to adjust for DNA extraction and amplification efficiency. HHV-8 viremia was undetectable in all three groups. HHV-6 viremia was detected in a substantial fraction of the samples examined (18.6%) without significant differences among the three groups (ST segment elevation myocardial infarction: 17.2%; stable coronary artery disease: 14.3%; patients without coronary and carotid artery atherosclerosis: 25%). Furthermore, no significant differences in plasma HHV-6 load were observed amongst the three groups of patients. These findings indicate that coronary instability is not associated specifically with active HHV-6 or HHV-8 infection. However, an unusually high rate of active HHV-6 infection was documented among patients without atherosclerosis admitted to hospital with cardiac disease.

Demonstration of Chlamydophila pneumoniae, Mycoplasma pneumoniae, Cytomegalovirus, and Epstein-Barr virus in atherosclerotic coronary arteries, nonrheumatic calcific aortic and rheumatic stenotic mitral valves by polymerase chain reaction.

OBJECTIVE: The aim of this study was to investigate whether bacterial and viral infectious agents can be demonstrated in atherosclerotic lesions of patients with coronary artery disease (CAD) as well as in stenotic aortic and mitral valves from patients undergoing heart valve replacement. METHODS: In this cross-sectional study, the presence of Chlamydophila pneumoniae, Mycoplasma pneumoniae, Cytomegalovirus (CMV), and Epstein-Barr virus (EBV) was investigated by polymerase chain reaction in atherosclerotic and non-atherosclerotic vascular samples taken from patients undergoing coronary artery bypass surgery due to CAD, and from patients undergoing aortic (AVR) and/or mitral valve replacement (MVR) secondary to valvular stenosis. For statistical analyses ANOVA, Chi-square test or Fisher's exact test were used. RESULTS: The presence of C. pneumoniae, M. pneumoniae, and CMV in atherosclerotic versus non-atherosclerotic samples was as follows: 30% vs. 16.7% (p=0.222), 6.7% vs. 3.3% (p=0.554), and 10% vs. 0% (p=0.076), respectively. In valve group, same pathogens were present in AVR and MVR patients as follows: 24.2% vs. 21.4% (p=0.773), 9.1% vs. 7.1% (p=0.758), and 21.2% vs. 11.9% (p=0.275). EBV DNA was not detected in any of vascular specimens, but in one (3%) patient with AVR (p=0.256). CONCLUSION: Our results suggest that C. pneumoniae, M. pneumoniae, and CMV are present with similar frequency both in atherosclerotic and non-atherosclerotic vessels. We conclude that although non-atherosclerotic, vascular samples of CAD patients are invaded by infectious agents as like as atherosclerotic vessels. We further conclude that C. pneumoniae, M. pneumoniae, and CMV are present in stenotic aortic and mitral valves and atherosclerotic tissues with similar frequency indicating that atherosclerosis and valvular stenosis might share a common etiology related to infection.

Detection of human herpesvirus 6 DNA but not human herpesvirus 7 or 8 DNA in atherosclerotic and nonatherosclerotic vascular tissues.

INTRODUCTION: Various viral infections are thought to play a role in the development of atherosclerosis. A number of studies suggest that certain viruses from the Herpesviridae family in particular may lead to atherosclerosis. METHODS: We investigated the presence of human herpesvirus 6 (HHV-6), human herpesvirus 7 (HHV-7), and human herpesvirus 8 (HHV-8) DNA in carotid, iliac, and coronary artery specimens obtained from a group of adult autopsy cases by means of polymerase chain reaction (PCR) analysis and nested PCR techniques. A 28-subject study group with at least type IV atherosclerosis and a 25-subject control group with no visible atherosclerosis were enrolled. RESULTS: HHV-6 DNA was found in the carotid artery specimen of 1 subject with atherosclerosis, in an iliac artery specimen of another subject, and in the iliac artery specimen of one of the control subjects. HHV-7 or HHV-8 DNA was not found in either the atherosclerosis or control cases. CONCLUSIONS: This study is the first to demonstrate the presence of HHV-6 in atherosclerotic vascular tissues. HHV-7 and HHV-8 were not found in atherosclerotic tissues; however, further research on broader study groups and with different protocols is needed to determine whether these viruses play a role in the formation of atherosclerosis.

Impact of intimal pathogen burden in acute coronary syndromes--correlation with inflammation, thrombosis, and autoimmunity.

BACKGROUND: Increasing evidence supports a link between serological evidence of pathogen burden (PB) and the risk for future cardiovascular events. Our study evaluates the intimal presence of 4 pathogens in atheroma, clinically associated with acute coronary syndromes (ACS) and stable angina (SA), and the effect on the expression of intimal C-reactive protein (CRP), tissue factor (TF) and human heat-shock protein 60 (hHSP60). METHODS: Coronary atherectomy specimens retrieved from 60 primary lesions of patients with ACS (n=35) or SA (n=25) were assessed immunohistochemically for the presence of Chlamydia pneumoniae (Cpn), Helicobacter pylori (HP), Cytomegalovirus (CMV) and Epstein­Barr Virus (EBV) and for the expression of CRP, TF, and hHSP60. RESULTS: Analysis revealed eight lesions without, 22 lesions with one, 19 lesions with two, seven lesions with three, and four lesions with four pathogens. Cpn was present in 73%, HP in 31%, CMV in 16%, and EBV in 40%. Mean value of PB in ACS-lesions was significantly increased. Expressions of CRP, TF, and hHSP60 were significantly higher in ACS lesions. The number of infectious pathogens correlated significant with the expressions of CRP, TF, and hHSP60. CONCLUSIONS: Our data demonstrate the impact of PB in plaque instability and suggest local proinflammatory, prothrombotic, and proimmunogenic effects.

Analysis of foot-and-mouth disease virus integrin receptor expression in tissues from naïve and infected cattle.

Foot-and-mouth disease (FMD) is a highly contagious viral disease of cloven-hoofed animals principally affecting cattle, pigs and sheep. FMD virus (FMDV) uses the alpha(V)beta(1), alpha(V)beta(3), alpha(V)beta(6), and alpha(V)beta(8) integrins as receptors in vitro via a highly conserved arginine-glycine-aspartic acid amino acid sequence motif located within the betaG-betaH loop of VP1. Immunofluorescence and confocal microscopy were used to study the expression of two major FMDV receptors, alpha(V)beta(3) and alpha(V)beta(6), within epithelial tissues from FMDV-infected and uninfected cattle in order to understand the role of these receptors in tissue tropism. Integrin alpha(V)beta(6) was expressed by epithelial cells in tissues that are important sites for FMDV replication (i.e. tongue and coronary band). Integrin alpha(V)beta(3) was detected in epithelium of all tissues examined except tongue. In addition, alpha(V)beta(3) expression was associated with blood vessels in all tissues examined. In infected tissues, alpha(V)beta(6) integrin was distributed on the surface of those epithelial cells also expressing FMDV antigen. Although integrin alpha(V)beta(3) has been shown to be a receptor for FMDV, no expression of alpha(V)beta(3) was associated with FMDV-positive keratinocytes in the tongue. In contrast, podal epithelial cells containing FMDV antigen also expressed alpha(V)beta(3) integrin. Thus, at the cellular level the expression of these two integrins correlates with susceptibility to infection and may contribute substantially to viral tropism in FMD pathogenesis.

Use of in vivo phage display to engineer novel adenoviruses for targeted delivery to the cardiac vasculature.

We performed in vivo phage display in the stroke prone spontaneously hypertensive rat, a cardiovascular disease model, and the normotensive Wistar Kyoto rat to identify cardiac targeting peptides, and then assessed each in the context of viral gene delivery. We identified both common and strain-selective peptides, potentially indicating ubiquitous markers and those found selectively in dysfunctional microvasculature of the heart. We show the utility of the peptide, DDTRHWG, for targeted gene delivery in human cells and rats in vivo when cloned into the fiber protein of subgroup D adenovirus 19p. This study therefore identifies cardiac targeting peptides by in vivo phage display and the potential of a candidate peptide for vector targeting strategies.

Detection of cytomegalovirus in atherosclerotic plaques and nonatherosclerotic arteries.

Several studies have reported an association between infectious agents and atherosclerosis. Cytomegalovirus (CMV) is the most commonly implicated viral pathogen. However, the role of CMV in atherosclerosis remains obscure. The present study evaluated the presence of CMV DNA in atherosclerotic plaques and normal vessel walls. A total of 40 arterial specimens from coronary plaques and 27 samples from normal vessels were obtained from 26 patients who underwent aortocoronary bypass surgery. The specimens were analyzed by polymerase chain reaction for the presence of the CMV immediate early genomic region. CMV DNA was detected in 9 out of 26 patients (34.6%). Viral DNA was detected in both nonatherosclerotic tissues and atherosclerotic plaques. No statistically significant differences were observed between normal and diseased vessels. Our findings, in accordance with previous studies, do not support a direct causative role of CMV in the development of atherosclerotic plaques.

A diet high in saturated fat and cholesterol accelerates simian immunodeficiency virus disease progression.

Several lines of evidence suggest that dietary fat and cholesterol may play a role in the pathogenesis of human immunodeficiency virus (HIV) infection and disease progression. We examined the effect that an atherogenic diet (AD) high in saturated fatty acids and cholesterol has on disease progression and systemic inflammation in the simian immunodeficiency virus (SIV)-infected macaque model of acquired immunodeficiency syndrome. Macaques fed an AD had significantly more rapid disease progression, resulting in an increased risk of SIV-related death compared with that in control macaques (hazard ratio, 5.4 [95% confidence interval, 1.7-17.0]; P<.001). Peak viral load was higher in the AD group compared with control values, but further statistically significant differences were not detected at viral set point. The baseline plasma interleukin-18 level after 6 months of the AD was predictive of disease progression. Our findings may have important implications for HIV-infected individuals, because they suggest that dietary changes and manipulation of lipid metabolism could offer potential benefits by slowing disease progression.

Vascular transfer of adenovirus is augmented by nitric oxide in the rat heart.

Reversible opening of the endothelial barrier remains a major obstacle when hearts are transfected via the coronary system. Our aim was to establish an experimental system permitting the continuous analysis of vascular transfer of virus in the intact heart. Isolated saline-perfused rat hearts were inverted and covered with a latex cap to collect interstitial transudate (IT) on the pericardial surface. Adenovirus (10(9) pfu/ml) was stably labeled with rhodamine fluorescent dye. Analysis of IT and coronary perfusate revealed that under baseline conditions, adenovirus in the IT reached 75% of its vascular concentration within 3 min. The nitric oxide-donors S-nitroso-N-acetyl penicillamine (SNAP) and bradykinin (BK) were the most effective substances to increase total IT volume and adenoviral interstitial concentration. Perfusion with 9% serum markedly reduced IT volume flow and delayed the SNAP/BK effect. Our findings demonstrate that SNAP and BK effectively increased coronary transfer of adenovirus suggesting that the inverted isolated heart is a suitable model to optimize vascular transfer of virus under standardized conditions.

Ebola virus glycoprotein-mediated anoikis of primary human cardiac microvascular endothelial cells.

Ebola virus glycoprotein (EGP) has been implicated for the induction of cytotoxicity and injury in vascular cells. On the other hand, EGP has also been suggested to induce massive cell rounding and detachment from the plastic surface by downregulating cell adhesion molecules without causing cytotoxicity. In this study, we have examined the cytotoxic role of EGP in primary endothelial cells by transduction with a replication-deficient recombinant adenovirus expressing EGP (Ad-EGP). Primary human cardiac microvascular endothelial cells (HCMECs) transduced with Ad-EGP displayed loss of cell adhesion from the plastic surface followed by cell death. Transfer of conditioned medium from EGP-transduced HCMEC into naive cells did not induce loss of adhesion or cell death, suggesting that EGP needs to be expressed intracellularly to exert its cytotoxic effect. Subsequent studies suggested that HCMEC death occurred through apoptosis. Results from this study shed light on the EGP-induced anoikis in primary human cardiac endothelial cells, which may have significant pathological consequences.

HIV infection, highly active antiretroviral therapy and the cardiovascular system.

Cardiovascular complications in the course of human immunodeficiency virus (HIV) infection are multifactorial and may be caused by the virus itself or by the related opportunistic infections and neoplasms. Highly active antiretroviral therapy (HAART) has prolonged many patients' lives, but many cardiac sequelae of HIV are not affected by HAART and continue to develop even with treatment. In addition, HAART itself causes in a high proportion of patients a metabolic syndrome, characterized by lipodystrophy/lipoatrophy, dyslipidemia and insulin resistance that may be associated with an increase in peripheral artery and coronary artery diseases. Careful cardiovascular evaluation in the course of HIV disease can identify cardiac complications early enough to treat. All HIV-infected patients candidate to antiretroviral therapy and patients already under treatment should undergo an assessment that includes the evaluation of the cardiovascular risk with the available guidelines.

Role of NADPH oxidase in cytomegalovirus-induced proliferation of human coronary artery smooth muscle cells.

A number of infectious agents have been implicated in the development of vascular diseases such as atherosclerosis and posttransplantation arterial restenosis. Cytomegalovirus (CMV) has been reported to cause obliteration of coronary arteries by a progressive vasculopathy that involves proliferation of medial smooth muscle cells (SMC). In this study, we report that CMV enhances the serum-induced proliferation of human coronary SMC through activation of a superoxide-generating NADPH oxidase. Exposure of SMC to CMV for 2 h was associated with an 80% increase in NADPH oxidase. This increase in oxidase activity was associated with a two-fold increase in serum-induced DNA synthesis (5-bromo-2'-deoxyuridine incorporation) and significant interleukin-8 (IL-8) production by SMC. Diphenylene iodonium, an inhibitor of NADPH oxidase, significantly inhibited CMV-induced IL-8 production and promotion of serum-induced DNA synthesis. Similar effects were seen following pretreatment of SMC with N-acetyl cysteine, a potent antioxidant, suggesting that oxidative stress following CMV exposure might be responsible for triggering the proliferation of SMC. From this study, we conclude that CMV-mediated promotion of SMC growth is redox sensitive and may be mediated by NADPH oxidase.

[Influenza viruses and atherosclerosis: the role of atherosclerotic plaques in prolonging the persistent form of influenza infection]. / Virusy grippa i ateroskleroz: rol' ateroskleroticheskikh bliashek v podderzhanii persistentnoi formy grippoznoi infektsii.

It was established that viral particles, like low-density lipoproteins (LDLP), when subjected to some modification changes, lost their ability to be internalized by tissue somatic cells and acquired tropism to macrophage cells. The data, obtained by us by using the polymerase chain reaction (PCR) method, made it possible to assert that atherosclerotic plaques, isolated from vessels of patients with ischemic heart disease (IHD) who underwent coronary bypass, contained RNA of the A(HINI) and AH3N3) influenza viruses. Whereas, the vessel portions, undamaged by atherosclerosis, did not contain any genetic substances of influenza viruses. It was for the first time that an experimentally supported understanding was expressed on that the atherosclerotic plaques serve as a "reservoir" for influenza viruses. It is also suggested that the mentioned plaques can be the carriers of influenza viruses for a long time, thus, prolonging the persistent form of influenza infection in the human body.

How to optimize in vivo gene transfer to cardiac myocytes: mechanical or pharmacological procedures?

An efficient gene delivery system is a prerequisite for myocardial gene therapy. Among the various procedures studied so far, catheter-based percutaneous gene delivery to the myocardium through the coronary vessels seems the most relevant to routine clinical practice; however, the optimal conditions remain to be determined. We selectively infused adenoviral vectors encoding luciferase (1 x 10(9) PFU) or beta-galactosidase (1 x 10(10) PFU) into coronary arteries of adult rabbits in various experimental conditions. Coronary artery occlusion for 30 sec, during and after adenovirus delivery, was required to observe luciferase activity in the target area of the circumflex artery (4.0 +/- 1.0 x 10(5) vs. 1.1 +/- 0.2 x 10(4) RLU/mg with and without coronary occlusion, respectively, p < 0.01, and 1.0 +/- 0.1 x 10(3) RLU/mg using nonselective infusion). When adenoviruses were delivered using high-pressure infusion (82 +/- 12 vs. 415 +/- 25 mmHg before and during infusion, respectively, p < 0.01), luciferase activity increased to 8.5 +/- 2.5 x 10(5) RLU/mg (p < 0.05 vs coronary occlusion alone). Coronary venous sinus occlusion with saline buffer retroinfusion starting before and during anterograde adenovirus delivery resulted in a further 4.7-fold increase in luciferase activity (4.4 +/- 0.8 x 10(6) RLU/mg, p < 0.01) with 5-25% blue-stained myocytes in the target area, compared with 0-5% with the other procedures. Histamine or VEGF-A(165) pretreatment, used to increase vascular permeability, slightly increased gene transfer efficiency (8.5 +/- 2.0 x 10(5) and 9.0 +/- 2.5 x 10(5) RLU/mg respectively, p < 0.05 vs. coronary occlusion alone). We conclude that catheter-mediated adenoviral gene transfer to cardiac myocytes through coronary vessels can be a very efficient procedure for myocardial gene therapy, particularly when the vector residence time and perfusion pressure in the vessels are increased.

HIV-1 penetrates coronary artery endothelial cells by transcytosis.

BACKGROUND: The pathogenesis of HIV-1-related cardiomyopathy is poorly understood, but HIV-1 has been detected in cardiomyocytes. Whether HIV-1 penetrates into the myocardium by infection of coronary artery endothelial cells (CAEC) or using transcellular or paracellular routes across CAEC has not been resolved. MATERIALS AND METHODS: A model of the CAEC barrier was constructed with primary CAEC (derived from human coronary vessels). Polymerase chain reaction (PCR) assay, infectious assay, and immunofluorescence were employed to show abortive nature of HIV-1 infection of CAEC. Tight junction (TJ) and cell adhesion proteins were visualized by immunofluorescence. The time course of HIV-1 invasion was measured by HIV-1 RNA assay. Inulin permeability assay determined paracellular leakage. Transmission electron microscopy demonstrated virus-induced endothelial vacuolization. RESULTS: Despite a strong display on CAEC of CXCR4 and a lesser expression of CCR3 and CCR5, HIV-1 did not productively replicate in CAEC, as shown by infectious assay, immunofluorescence, and electron microscopy. HIV-1 infection of CAEC was abortive with minimal reverse transcription of strong stop DNA and pol but not full-length or two LTR DNA circles. Upon infection of the model with 1 million RNA copies of HIV-1JR-FL, virus penetration 2 hr postinfection (PI) was negligible but increased by 1,750% 24 hr PI. The paracellular permeability increased during this period by only 25%. Neither AOP-RANTES nor v-MIPII significantly reduced HIV-1JR-FL invasion. Virus infection did not alter the integral TJ protein occludin and the TJ-associated protein ZO-1. HIV-1 exposed CAEC and brain microvascular endothelial cells (BMVEC) developed extensive cytoplasmic vacuolization with retroviral-like particles in the vacuoles. CONCLUSIONS: The endothelium is not an impenetrable barrier to HIV-1. The virus opens a transcellular route across coronary and brain endothelia in cytoplasmic vacuoles.

Improved adenovirus vectors for infection of cardiovascular tissues.

To identify improved adenovirus vectors for cardiovascular gene therapy, a library of adenovirus vectors based on adenovirus serotype 5 (Ad5) but carrying fiber molecules of other human serotypes, was generated. This library was tested for efficiency of infection of human primary vascular endothelial cells (ECs) and smooth muscle cells (SMCs). Based on luciferase, LacZ, or green fluorescent protein (GFP) marker gene expression, several fiber chimeric vectors were identified that displayed improved infection of these cell types. One of the viruses that performed particularly well is an Ad5 carrying the fiber of Ad16 (Ad5.Fib16), a subgroup B virus. This virus showed, on average, 8- and 64-fold-increased luciferase activities on umbilical vein ECs and SMCs, respectively, compared to the parent vector. GFP and lacZ markers showed that approximately 3-fold (ECs) and 10-fold (SMCs) more cells were transduced. Experiments performed with both cultured SMCs and organ cultures derived from different vascular origins (saphenous vein, iliac artery, left interior mammary artery, and aorta) and from different species demonstrated that Ad5.Fib16 consistently displays improved infection in primates (humans and rhesus monkeys). SMCs of the same vessels of rodents and pigs were less infectable with Ad5.Fib16 than with Ad5. This suggests that either the receptor for human Ad16 is not conserved between different species or that differences in the expression levels of the putative receptor exist. In conclusion, our results show that an Ad5-based virus carrying the fiber of Ad16 is a potent vector for the transduction of primate cardiovascular cells and tissues.

The possible role of human cytomegalovirus (HCMV) in the origin of atherosclerosis.

BACKGROUND: The biological properties of some herpesviruses such as the ability of latent persistency in the host cells and the presence of viral DNA in atherosclerotic lesions, suggest the possible role of herpesviruses in the development of atherosclerosis. Although many authors proved the presence of viral DNA in arterial wall tissue, the role of herpesviruses in the origin and progress of atherogenesis still remains unclear. OBJECTIVES: The aim of this study was to confirm the presence of viral DNA in arterial wall and to associate the presence of these viruses with the development of atherosclerosis in patients with ischemic heart disease (IHD). STUDY DESIGN: A possible role of HCMV, EBV and HHV6 in the development of atherosclerosis was tested in 244 IHD patients and 87 coronarographically negative controls. The presence of viral DNA in aortic and venous walls, as well as in a peripheral blood samples was tested by the use of polymerase chain reaction (PCR) accompanied by, immunological tests for anti-virus antibodies IgM and IgG types for all experimental groups. RESULTS: The genomic DNA of HCMV was found in 76 and 59%, DNA of EBV in 59 and 50%, and DNA of HHV6 in 0.08 and 0.0%, of arterial walls of IHD patients and non-ischemic control group, respectively. No viral DNA was found in venous samples. Significant association (P < 0.01) has been proved between CMV infection and IHD. CONCLUSIONS: Our results suggest that HCMV and EBV can be found in the arterial wall, so that the arterial wall could be a potential site of persistency of those viruses. We also proved a significant association between the presence of HCMV DNA in aortic walls and atherosclerosis. Despite of the high genetic and biological similarity between CMV and HHV6 no substantial role of HHV6 in atherosclerosis has been proved.

Effects of human cytomegalovirus immediate-early proteins on p53-mediated apoptosis in coronary artery smooth muscle cells.

BACKGROUND: Restenotic and atherosclerotic lesions often contain smooth muscle cells (SMCs), which display high rates of proliferation and apoptosis. Human cytomegalovirus (HCMV) may increase the incidence of restenosis and predispose to atherosclerosis. Although the mechanisms contributing to these processes are unclear, studies demonstrate that one of the immediate-early (IE) gene products of HCMV, IE2-84, binds to and inhibits p53 transcriptional activity. Given the role of p53 in mediating apoptosis, we studied the ability of IE2-84 to inhibit p53-dependent apoptosis in human coronary artery SMCs. METHODS AND RESULTS: Apoptosis of SMCs was induced either by use of an adenovirus vector encoding human wild-type p53 protein or by treatment with doxorubicin. HCMV IE1-72 and IE2-84, the major IE proteins of HCMV, were overexpressed separately with adenovirus vectors encoding each protein, and the effects on p53-induced apoptosis were examined by both nick end-labeling (TUNEL) assay and flow cytometry. Expression of IE2-84, but not IE1-72, protected SMCs from p53-mediated apoptosis. CONCLUSIONS: These data indicate that an HCMV IE protein antagonizes p53-mediated apoptosis, suggesting a pathway by which HCMV infection predisposes to SMC accumulation and thereby contributes to restenosis and atherosclerosis.

Cytomegalovirus infection and cardiac allograft vasculopathy.

There is a wealth of clinical and experimental evidence indicating the interaction of cytomegalovirus (CMV) infection and rejection in cardiac and other solid organ allografts. A plausible explanation for this association comes from data showing that therapy with biologicals, sepsis, and rejection, all lead to the release of TNF-alpha which, upon binding to its receptor, activates NF-kB. TNF-alpha is also able to stimulate the activity of the CMV-IE enhancer/promoter region. CMV infection of several cell lines leads to NF-kB activation. NF-kB binding sites are present in regulatory regions of various cellular and viral genes, including the IE enhancer region of CMV. In a reciprocal situation, CMV infection, most likely via gamma-interferon, leads to upregulation of MHC antigens in the transplant and, thereby, to increased transplant immunogenicity. Thus, a vicious circle is induced. We have investigated in detail the pathobiology of CMV and allograft vasculopathy (chronic rejection) in experimental animals, using aortic and cardiac allografts as well as a trachea model. The results may be summarized as follows: Infection of the recipient with rat CMV results in an early inflammatory response in the aortic and cardiac allograft vascular adventitia and intima (endothelialitis) and in the airway wall of tracheal allografts. This early inflammatory response leads to enhanced intimal thickness in aortic and cardiac allografts and enhanced luminal occlusion of tracheal allografts. Timewise, this coincides with early activation of intragraft inflammatory leukocytes and increased mRNA of various growth factors and cytokines. When the recipients receive gancyclovir, the enhanced intimal response in aortic and cardiac allografts and luminal occlusion in tracheal allografts is entirely abolished. Gancyclovir treatment dramatically reduces the inflammatory response in the allograft, and thereby growth factor synthesis in response to injury. However, gancyclovir does not prevent the expression of IE antigen of CMV, suggested to inactivate tumor suppressor protein p53 predisposing smooth muscle cells to increased growth. Taken together, the effect of CMV infection on cardiac allograft dysfunction is bidirectional and biphasic. The bidirectional nature emerges from the observations that acute CMV infection may accelerate acute rejection, and, on the other hand, acute alloimmune response-associated cytokine response may activate latent CMV infection. The biphasic effect of CMV on allograft dysfunction refers to its early and late detrimental effects, i.e. during the time of acute and chronic rejection. These two effects of CMV on allograft dysfunction emphasize the need for precise diagnosis of CMV infection in transplant recipients and pre-emptive or prophylactic anti-viral therapy. The benefits of this strategy may not be evident during the early post-transplant period, but 5-10 years after transplantation they manifest as better graft survival.