tokens: Two major protein-binding sites within the negative regulatory element of the human immunodeficiency virus type 1 long terminal repeat have been identified .
folded_tokens: two major protein-binding sites within the negative regulatory element of the human immunodeficiency virus type 1 long terminal repeat have been identified .
labels: O B-DNA_domain_or_region I-DNA_domain_or_region I-DNA_domain_or_region O O B-DNA_domain_or_region I-DNA_domain_or_region I-DNA_domain_or_region O O B-virus I-virus I-virus O O O O O O O O O