tokens: To characterize these regulatory elements further , mutations in these regions were inserted into both the 5' and 3' HIV LTRs and infectious proviral constructs were assembled .
folded_tokens: to characterize these regulatory elements further , mutations in these regions were inserted into both the 5' and 3' hiv ltrs and infectious proviral constructs were assembled .
labels: O O O B-DNA_family_or_group I-DNA_family_or_group O O O O O O O O O O O O O O B-DNA_domain_or_region I-DNA_domain_or_region O B-other_artificial_source I-other_artificial_source I-other_artificial_source O O O