Endothelial cells (EC) are common targets of permissive infection by human cytomegalovirus (HCMV) inEndothelial cells (EC) are major targets of human cytomegalovirus (HCMV) during acute infection of an immunocompromised host (18). In addition to contributing to hematogenous viral dissemination (7,8,13,19,23), infected EC may trigger direct vascular injury if viral induced cytopathogenicity occurs. In support of these in vivo data, susceptibility of cultured human venous EC (HUVEC) to productive lytic HCMV infection has been demonstrated (25). However, studies of interactions of HCMV with human arterial EC (HAEC) have generated conflicting results. Whereas reports about noncytopathic persistence of HCMV in cultured aortic EC (6) raised the possibility of different susceptibilities of EC depending on their vascular origin, Knight et al. (9) have described similar cytopathologies of HCMV in HUVEC, HAEC, and microvascular EC with regard to adhesion molecule induction. The respective usage of fibroblast-propagated and EC-propagated HCMV strains might provide an explanation for the discrepancies. While such interstrain differences in the cytopathic potential of HCMV in HUVEC are well established (11,20,22,24), the lytic potentials of various HCMV strains in HAEC have not yet been determined.In the present investigation we have tested the hypothesis that interstrain differences in viral host cell tropism, rather than properties inherent to EC of different vascular origins, determine the outcome of HCMV infection. To this end we have performed a detailed analysis of viral replication kinetics, long-term evolution of cytopathology, and lytic end points, comparing EC derived from human adult iliac artery, placental microvasculature, and umbilical vein following inoculation with various HCMV strains.
Efficient lytic infection of HAEC by EC-propagated HCMV strains.In a first set of experiments, HCMV strains VHL/E (kindly provided by W. J. Waldman) (24) and TB40/E (22) were tested for cytopathic potential in HAEC. Both strains were propagated in HUVEC to preserve the natural endothelial cytopathogenicity of the original isolates. To obtain high-titer virus preparations, EC-propagated virus stocks were inoculated with fibroblasts for a single round of infection, harvested at 100% cytopathic effect (CPE), and made cell free by centrifugation. HAEC were isolated from adult human iliac arteries of bypass recipients by mechanically removing the endothelial layer as previously described (1, 2) and were cultured in EGM-2 medium (Clonetics, Walkersville, Md.) containing 2% fetal calf serum on culture flasks (Greiner, Frickenhausen, Germany) coated with 2% gelatin. For infection, cells were preincubated for 2 h in heparin-free medium, inoculated with cell-free virus at multiplicities of infection (MOI) of 0.1, 1, and 10, and incubated for 90 min before removal of the inoculum. The medium was replaced at 48-h intervals. The kinetics of viral antigen expression in HAEC cultures was analyzed by indirect immunoperoxidase detection of imm...