INCREASED EXPRESSION OF TISSUE FACTOR MESSENGER-RNA AND PROCOAGULANT ACTIVITY IN OVINE LENTIVIRUS-INFECTED ALVEOLAR MACROPHAGES

To link ovine lentivirus infection to lung tissue damage, we studied t he procoagulant response in alveolar macrophages from experimentally i nfected lambs and in in vitro infected alveolar macrophages. We cloned ovine tissue factor cDNA and analysed its in vitro expression by Nort hern blotting. Visna-maedi virus induced tissue factor mRNA. In order to correlate this mRNA induction with its cellular function, we analys ed macrophage procoagulant activity after in vitro and in vivo infecti on. The procoagulant activity was increased by interaction with the vi rus in both cases. Thus, visna-maedi virus-induced expression of tissu e factor mRNA was associated with enhanced macrophage procoagulant act ivity. These findings indicate an active role of alveolar macrophages in the pathogenesis of these inflammatory lung lesions.