Cell phenotypes in the efferent lymph of sheep persistently infected with Border disease virus

SUMMARY The prefemoral efferent lymphatics of sheep persistently infected (PI) with Border disease virus (BDV) were cannulated in order to study the effects of the virus on cells of the immune system. Efferent lymphocytes recovered from PI sheep were phenotyped using a panel of monoclonal antibodies (MoAb) specific for ovine cell-surface markers and compared to lymphocytes recovered from normal, healthy controls. PI sheep had an increased percentage of cells expressing the T cell-associated molecules CD5, CD4, CD8 and TI9, also an increase in cells expressing CD1 and a population of cells expressing low levels of the T19 molecule which was not present in control sheep. The lymphocytes were examined for the presence of BDV using virus-specific MoAb. On average 8.5% of the efferent lymphocytes from PI sheep carried virus antigen. BDV antigen was also found in the mononuclear cells and connective tissue of lymph nodes indicating widespread virus dissemination within the lymphoid system of PI sheep.