Human T-cell leukemia virus types I ( HTLV-I ) and II ( HTLV-II ) have two nonstructural trans-acting regulatory genes , tax and rex , located in the 3' region of the viral genome .
human t-cell leukemia virus types i ( htlv-i ) and ii ( htlv-ii ) have two nonstructural trans-acting regulatory genes , tax and rex , located in the 3' region of the viral genome .
B-virus I-virus I-virus I-virus I-virus I-virus O B-virus O O O O B-virus O O O B-DNA_family_or_group I-DNA_family_or_group I-DNA_family_or_group I-DNA_family_or_group O B-DNA_domain_or_region O B-DNA_domain_or_region O O O O B-DNA_domain_or_region I-DNA_domain_or_region O O B-DNA_domain_or_region I-DNA_domain_or_region O