Enhanced cytomegalovirus infection in atherosclerotic human blood vessels.

Human cytomegalovirus (CMV) is a possible co-factor in atherogenesis and vascular occlusion, but its ability to actively infect medium and large blood vessels is unclear. A vascular explant model was adapted to investigate CMV infection in human coronary artery, internal mammary artery (IMA), and saphenous vein (SV). Vascular explants were inoculated with CMV Towne or low-passage clinical isolate and examined in situ for CMV cytopathic effect and immediate-early and early antigens, as indicators of active infection. At 5 to 7 days after inoculation, we found that CMV Towne actively infected eight of eight different atherosclerotic blood vessel explants (coronary artery, n = 4; SV and IMA grafts, n = 4), whereas it only infected 2 of 14 nonatherosclerotic blood vessel explants (SV, n = 10; IMA, n = 4) (P = 0.001). The CMV clinical isolate actively infected none of six sets of nonatherosclerotic SV explants at 5 to 7 days after inoculation. The active CMV infections involved adventitial and, less frequently, intimal cells. A small subset of infected cells in atherosclerotic tissue expresses the endothelial cell marker CD31. Smooth muscle cells residing in both atherosclerotic and nonatherosclerotic blood vessels were free of active CMV infections even after all vascular tissue layers were exposed to the virus. In contrast, active CMV Towne infection was evident at 2 days after inoculation in smooth muscle cells and endothelial cells previously isolated from the SV tissues. We conclude that active CMV infection is enhanced in atherosclerotic blood vessels compared to atherosclerosis-free vascular equivalents, and this viral activity is restricted to subpopulations of intimal and adventitial cells.

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.

Detection of Chlamydia pneumoniae but not cytomegalovirus in occluded saphenous vein coronary artery bypass grafts.

BACKGROUND: A causal relation between atherosclerosis and chronic infection with Chlamydia pneumoniae and/or cytomegalovirus (CMV) has been suggested. Whether the unresolved problem of venous coronary artery bypass graft occlusion is related to infection with C pneumoniae and/or CMV has not been addressed. METHODS AND RESULTS: Thirty-eight occluded coronary artery vein grafts and 20 native saphenous veins were examined. Detection of C pneumoniae DNA was performed by use of nested polymerase chain reaction (PCR). Homogenisates from the specimen were cultured for identification of viable C pneumoniae. Both conventional PCR and quantitative PCR for detection of CMV DNA were applied. Differential pathological changes (degree of inflammation, smooth muscle cell proliferation [MIB-1]) were determined and correlated to the detection of both microorganisms. C pneumoniae DNA could be detected in 25% of occluded vein grafts. Viable C pneumoniae was recovered from 16% of occluded vein grafts. Except for 1 native saphenous vein, all control vessels were negative for both C pneumoniae detection and culture. All pathological and control specimens were negative for CMV DNA detection. Pathological changes did not correlate with C pneumoniae detection. CONCLUSIONS: Occluded aorto-coronary venous grafts harbor C pneumoniae but not CMV. The detection of C pneumoniae in occluded vein grafts warrants further investigation.