IMMUNOELECTRON MICROSCOPIC LOCALIZATION OF HUMAN T-CELL LEUKEMIA VIRUS TYPE-I ANTIGENS

The location of human T-cell leukemia virus type I (HTLV-I) antigens in HTLV-I-producing cells, HUT 102 and MT-2, was described on the basis of immunoelectron microscopic studies and immunoblotting analysis. The direct and indirect peroxidase-labeled antibody methods with monoclonal and polyclonal antibodies to various HTLV-I antigens as well as sera from patient with adult T-cell leukemia were used for the immunoelectron microscopic observation. In HTLV-I-producing cells fixed with paraformaldehyde and incubated in cell suspension with sera from ATL patients, the viral envelope and plasma membrane are positively stained. In the specimens frozen-sectioned and incubated with the patient sera after fixation, positive staining is observed mainly on the viral envelope, plasma membrane, nuclear envelope, and endoplasmic reticulum of these cells. gag gene product p24 was localized in the viral core, and p19 was in the viral envelope and core and some parts of the plasma membrane. env gene product gp46x was deduced to be localized on the viral envelope and the plasma membrane, and env precursor protein gp62x was deduced to be in the endoplasmic reticulum and the nuclear envelope. pX gene product p40x was localized mainly in the euchromatin regions of the nuclei of HTLV-I-producing cells, but p68x of MT-2 cells was localized mainly in the nuclear envelope and the endoplasmic reticulum. The p68x detected in MT-2 cells with anti-p40x serum was deduced to be a fused protein consisting of a part of pX and env gene products and to share epitopes with p40x.