Flow cytometric analysis of PBMCs isolated from BLV-negative and BLV-positive cattle with proviral loads of <100 and > 100 copies per 105cells. (A) Dual color flow cytometric analysis of PBMCs isolated from BLV-negative cattle (animals N790 and N791) and BLV-infected cattle with proviral loads < 100 copies per 105 cells (animals N818, N789) and > 100 copies per 105 cells (animals N787, N733, N823, N788 and N10). Each profile was separated into four quadrants on the basis of control staining (cells were incubated with normal mouse serum and then stained with appropriate secondary antibodies), which signify single-positive [orange (574 nm) and red (660 nm)], double-negative, or double-positive staining. The values in each gate indicate the percentage of the total PBMC population. (B) The proviral load and the percentage of CD5+ IgM+ cells, CD5- IgM+ B cells, CD4+ T cells and CD8+ T cells in the indicated cattle.