HTLV-2 replication in human B- and T-cell lines. At day 15 after infection, cultured cells were observed in phase contrast microscopy and analyzed for detection of both intracellular HTLV-2 p19 Ag by IIF and tax gene by PCR. Light microscopy showed clear signs of cell lysis for RJ2.2.5 and normal growth for the other cell lines. Cell fluorescence profiles obtained incubating cell cytospins with mAb specific for p19 Ag, followed by rhodamine antimouse IgG, showed an inverse association between IIF positivity and cell viability. Confocal images showed polarization (arrows) of Gag p19-staining (yellow) near the cell membrane in many RJ2.2.5 cells (very strong) and in few Raji cells (weak). The qualitative PCR and Southern blot analysis of tax2 present in 105 cells resulted as a major band in RJ2.2.5 cells. In the other cell lines, the tax signal decreased correlating with the ability of each cell line to support HTLV-2 replication. Scale bar: 2 μm for Raji, RJ2.2.5, and BLS-1; 5 μm for RJ/CIITA.
