Infection of endothelial cells with Equine herpesvirus-1 (EHV-1) occurs where there is activation of putative adhesion molecules: a mechanism for transfer of virus

Evidence is presented to show that activation of endothelial and leucoyte a dhesion molecules is a key step in transferring virus from infected leucocy tes; and determines the restricted tissue tropism. A range of tissues from 2 experimentally infected mares in late pregnancy at 4 and 8 days after inf ection with EHV-1 were compared with those from normal pregnant and nonpreg nant mares, Rabbit antisera to equine activated endothelial cell molecules were used to identify which tissues expressed these molecules in normal non gravid and gravid mares, and to investigate whether the range of tissues wa s altered in pregnant mares as a consequence of infection. The results indi cated that the endothelium of the pregnant reproductive tract did express t hese molecules. In the 2 pregnant mares infected with EHV-1, the endothelia l cells in the nasal mucosa also expressed these activated endothelial cell molecules. Therefore, the sites expressing these molecules closely correla ted with those where virus infection of endothelial cells has been describe d and is consistent with experimental in vitro data, indicating that expres sion of these molecules is an essential stage in the transference of virus from leucocytes to endothelial cells.