Human T-cell leukemia virus type 1 ( HTLV-1 ) Tax is thought to play a pivotal role in immortalization of T cells .
human t-cell leukemia virus type 1 ( htlv-1 ) tax is thought to play a pivotal role in immortalization of t cells .
B-virus I-virus I-virus I-virus I-virus I-virus O B-virus O B-protein_molecule O O O O O O O O O O B-cell_type I-cell_type O