Discovery of noninfectious viral genes complementary to Marek's disease herpes virus in quail susceptible to cholesterol-induced atherosclerosis

Genomic rearrangements on VCAM1, SELE, APEG1and AIF1 loci in atherosclerosis

The inflammatory nature of atherosclerosis has been well established. However, the initial steps that trigger this response in the arterial intima remain obscure. Previous studies reported a significant rate of genomic alterations in human atheromas. The accumulation of genomic rearrangements in vascular endothelium and smooth muscle cells may be important for disease development. To address this issue, 78 post-mortem obtained aortic atheromas were screened for microsatellite DNA alterations versus correspondent venous blood. To evaluate the significance of these observations, 33 additional histologically normal aortic specimens from age and sex-matched cases were examined. Loss of heterozygosity (LOH) was found in 47,4% of the cases and in 18,2% of controls in at least one locus. The LOH occurrence in aortic tissue is associated to atherosclerosis risk (OR 4,06, 95% CI 1,50 to 10,93). Significant genomic alterations were found on 1p32-p31, 1q22-q25, 2q35 and 6p21.3 where VCAM1, SELE, APEG1 and AIF1 genes have been mapped respectively. Our data implicate somatic DNA rearrangements, on loci associated to leukocyte adhesion, vascular smooth muscle cells growth, differentiation and migration, to atherosclerosis development as an inflammatory condition.

Detection of avian oncogenic Marek's disease herpesvirus DNA in human sera

The avian herpesvirus Marek's disease virus (MDV) has a worldwide distribution and is responsible for T-lymphoma in chickens. The question as to whether MDV poses a public health hazard to humans was first raised when the virus was isolated in 1967. However, no irrefutable results have been obtained in immunological and virological studies. We used a nested-PCR to detect MDV DNA in human serum samples. A total of 202 serum samples from individuals exposed and not exposed to poultry was tested by nested-PCR for a target sequence located in the MDV gD gene. The assay system was specific and sensitive, making it possible to detect a single copy of the target sequence. Forty-one (20%) of the 202 serum samples tested positive for MDV DNA. The prevalence of MDV DNA was not significantly different in the group exposed to poultry and the group not exposed to poultry. There was also no difference due to age or sex. Alignment of the 41 gD sequences amplified from human sera with eight gD sequences amplified from MDV-infected chicken sera showed a maximum nucleotide divergence of 1.65%. However, four 'hot-spot' mutation sites were identified, defining four groups. Interestingly, two groups contained only human MDV-gD sequences. The status of the MDV genome detected in human blood is discussed.

Transactivation of latent Marek's disease herpesvirus genes in QT35, a quail fibroblast cell line, by herpesvirus of turkeys

The QT35 cell line was established from a methylcholanthrene-induced tumor in Japanese quail (Coturnix coturnix japonica) (C. Moscovici, M. G. Moscovici, H. Jimenez, M. M. Lai, M. J. Hayman, and P. K. Vogt, Cell 11:95-103, 1977). Two independently maintained sublines of QT35 were found to be positive for Marek's disease virus (MDV)-like genes by Southern blotting and PCR assays. Sequence analysis of fragments of the ICP4, ICP22, ICP27, VP16, meq, pp14, pp38, open reading frame (ORF) L1, and glycoprotein B (gB) genes showed a strong homology with the corresponding fragments of MDV genes. Subsequently, a serotype 1 MDV-like herpesvirus, tentatively name QMDV, was rescued from QT35 cells in chicken kidney cell (CKC) cultures established from 6- to 9-day-old chicks inoculated at 8 days of embryonation with QT35 cells. Transmission electron microscopy failed to show herpesvirus particles in QT35 cells, but typical intranuclear herpesvirus particles were detected in CKCs. Reverse transcription-PCR analysis showed that the following QMDV transcripts were present in QT35 cells: sense and antisense meq, ORF L1, ICP4, and latency-associated transcripts, which are antisense to ICP4. A transcript of approximately 4.5 kb was detected by Northern blotting using total RNA from QT35 cells. Inoculation of QT35 cells with herpesvirus of turkeys (HVT)-infected chicken embryo fibroblasts (CEF) but not with uninfected CEF resulted in the activation of ICP22, ICP27, VP16, pp38, and gB. In addition, the level of ICP4 mRNA was increased compared to that in QT35 cells. The activation by HVT resulted in the production of pp38 protein. It was not possible to detect if the other activated genes were translated due to the lack of serotype 1-specific monoclonal antibodies.

Murine gamma-herpesvirus 68 causes severe large-vessel arteritis in mice lacking interferon-gamma responsiveness: a new model for virus-induced vascular disease

Fundamental issues remain unresolved regarding the possible contribution of viruses to vascular pathology, as well as the role of the immune system in regulating these processes. Here we demonstrate that infection of mice with gamma-herpesvirus 68 (gammaHV68) provides a novel model for addressing these issues. Interferon-gamma receptor-deficient (IFNgammaR-/-) mice died weeks to months after gammaHV68 infection from a severe large-vessel panarteritis. GammaHV68-infected B cell-deficient and normal weanling mice exhibited milder large-vessel arteritis. Immunohistochemical analyses demonstrated gammaHV68 antigen in arteritic lesions and revealed a striking tropism of gammaHV68 for smooth muscle cells. These studies demonstrate that IFN-gamma is essential for control of chronic vascular pathology induced by gammaHV68 and suggest gamma-herpesviruses as candidate etiologic agents for human vasculitis.

Fibromuscular dysplasia in intramuscular arteries of Japanese quail (Coturnix coturnix japonica)

Fibromuscular dysplasia (FMD) was found in the intramuscular arteries of both commercial (normal) and mutant (LWC) strains of Japanese quail. The mutant strain LWC is afflicted with an inherited muscular dystrophy exhibiting myotonia. The arterial lesions were classified as medial fibroplasia or medial hyperplasia, both being subtypes of medial FMD. Some lesions showed extensive proliferation of medial smooth muscle into the vascular lumen, resulting in partial occlusion of the affected blood vessel. FMD occurred more frequently in the mutant LWC quail than in the commercial strain. Ischaemic changes were absent in the associated muscle structures in both strains. The significance of FMD in relation to the skeletal muscle changes in the mutant LWC strain remains unclear.

Possible role of viruses in atherosclerosis

Relative to the role of viruses in the pathogenesis of atherosclerosis a number of questions remain to be answered. Being ubiquitous, are the herpesvirus infections the norm or a diseased state in humans and animals? In all cases studied, including MDV induced atherosclerosis, direct isolation of viruses from arterial tissues has not been successful. Are herpesviruses always latent or dormant in vascular tissues? What is the relationship between provirus and disease development? Are they setting the stage for the pathogenic process triggered by certain environmental factors? Is hypercholesterolemia to trigger the development of atherosclerosis in the presence of proviruses? Is the reactivated and infectious virus the injuring agent that initiates atherogenesis? Or, are the proviral genes activated to transform arterial cells? In the latter case, are these proviral genes equivalent to "proto-atherogenes"? Hopefully, further study on Japanese quail will help clarify many of these questions.

Immunocytochemical and scanning electron microscopic studies of atherosclerosis in Japanese quail

The major cellular components of atherosclerotic lesions in several species have been shown to be smooth muscle cells (SMC) and macrophages. Many studies suggest the composition of a lesion varies depending on the stage of lesion development. For example, macrophages are believed to be involved in the initial events of fatty streak formation in many animals. This communication presents the first cellular study of quail atherosclerosis and demonstrates the alteration of cellular structure during the process of the disease in quail fed a cholesterol diet. Monoclonal antibodies to alpha-actin and chicken macrophages effectively identified the presence of SMC and macrophages, respectively, as constituents of the atherosclerotic lesions. Macrophage presence, as well as SMC proliferation, was observed in early lesions. Although the first cell type to be involved in the initial stages of atherogenesis cannot be defined, the results suggest early intervention of macrophages and SMC. Scanning electron microscopic examination of the aortic arch demonstrates the obvious differences in appearance of the endothelial surface of normal and diseased quail. The accumulation of subendothelial foam cells causes the lumen surface to bulge irregularly into the lumen. The results of the present study are important to the evaluation of the key cellular events of atherogenesis.

Effect of snake venom of Agkistrodon halys on atherosclerosis and blood characteristics in Japanese quail

Extracts of snake venom have been widely used for the treatment of vascular thrombotic diseases, yet the therapeutic mechanism is not clear. The effect of snake venom fractions on atherosclerosis in Japanese quail was studied. The venom of Agkistrodon halys was fractionated by DEAE-cellulose chromatography and the pooled protein fractions that resulted were injected intravenously into the quail with aortic atherosclerosis induced by dietary cholesterol. After 7 weeks of injections on every other day, the quail were killed, blood clotting times and serum cholesterol levels were determined, and aortic atherosclerosis and fatty liver were scored. The results showed that while no regression of atherosclerosis was observed, the lowering of serum cholesterol, prolonged blood clotting time and reduced fatty liver were significantly affected by the injection of one of the pooled protein fractions. This venom fraction contained two major protein components, one of which had arginine esterase activity. From this study we conclude that snake venom has little effect on the regression of atherosclerosis, but it prolongs blood clotting and lowers serum cholesterol.