Endothelial cell infection in vivo by equine infectious anaemia virus

Equine infectious anaemia virus (EIAV) infection of horses is characterized clinically by recurrent episodes of fever, thrombocytopenia and anaemia, I n vivo, the only site of virus replication that has been previously demonst rated for EIAV is the tissue macrophage. In this study, in situ hybridizati on for EIAV was combined with immunohistochemistry for cell-type-specific m arkers to identify infected endothelial cells. EIAV-infected endothelial ce lls and macrophages were detected in horses infected with either virulent w ild-type or with weakly virulent tissue culture-adapted strains of EIAV, Th e role of endothelial cell infection in the pathogenesis of EIAV remains un defined, but could contribute to the development of thrombocytopenia. Howev er, endothelial cell infection does not appear to be a determinant of virul ence for EIAV.