Aptamer characterized in that it comprises - a structure with sequence Mon 1 -Mon 2 - Mon 3 -Mon 4 -Mon 5 -Mon 6 -Mon 7 -Mon 8, responsible for specific binding to accessible areas in the complete folding of the 5'-UTR region of the genome of the human immunodeficiency virus type 1 (HIV-1), wherein Mon 1 to Mon 8 are monomers of a nucleic acid or of a chemical analogue of nucleic acid and wherein said monomers comprise a nitrogenous base, such that the nitrogenous base of Mon 1 is guanine, the nitrogenous base of Mon 2 is guanine, the nitrogenous base of Mon 3 is cytosine, the nitrogenous base of Mon 4 is adenine, the nitrogenous base of Mon 5 is a purine base selected from adenine or guanine, the nitrogenous base of Mon 6 is guanine, the nitrogenous base of Mon 7 is guanine and the nitrogenous base of Mon 8 is adenine; - an anterior flanking region Mon a4 -Mon a3 -Mon a2 -Mon a1 - bound to the monomer Mon 1 and a posterior flanking region -Mon b1 -Mon b2 -Mon b3 -Mon b4 bound to the monomer Mon 8 of said structure, wherein Mon a1 to Mon a4 and Mon b1 to Mon b4 are monomers of a nucleic acid or of a chemical analogue of nucleic acid and comprise a nitrogenous base, such that: i. the nitrogenous bases from Mon a1 to Mon a4 are independently selected from the following group: A, C, G, T and U; ii. the nitrogenous base of Mon b1 is complementary to the nitrogenous base of Mon a1; iii. the nitrogenous base of Mon b2 is complementary to the nitrogenous base of Mon 32; iv. the nitrogenous base of Mon b3 is complementary to the nitrogenous base of Mon a3; v. the nitrogenous base of Mon b4 is complementary to the nitrogenous base of Mon a4; wherein the complementarity rules to which these respective pairings of Mon a1 to Mon a4 with Mon b1 to Mon b4 are subjected are: A is complementary to T or U; C is complementary to G; G is complementary to C or U; T is complementary to A; U is complementary to A or G; and wherein the nitrogenous bases of the 4 monomers of the anterior flanking region closest to Mon 1 are paired with the nitrogenous bases of the 4 monomers of the posterior flanking region so that the sequence structure Mon 1 -Mon 2 -Mon 3 -Mon 4 -Mon 5 -Mon 6 -Mon 7 -Mon 8 forms a single-stranded terminal loop closing a double-stranded stem formed by the flanking regions with said paired monomers; or the enantiomer of said aptamer. - a structure with sequence Mon 1 -Mon 2 - Mon 3 -Mon 4 -Mon 5 -Mon 6 -Mon 7 -Mon 8, responsible for specific binding to accessible areas in the complete folding of the 5'-UTR region of the genome of the human immunodeficiency virus type 1 (HIV-1), wherein Mon 1 to Mon 8 are monomers of a nucleic acid or of a chemical analogue of nucleic acid and wherein said monomers comprise a nitrogenous base, such that the nitrogenous base of Mon 1 is guanine, the nitrogenous base of Mon 2 is guanine, the nitrogenous base of Mon 3 is cytosine, the nitrogenous base of Mon 4 is adenine, the nitrogenous base of Mon 5 is a purine base selected from adenine or guanine, the nitrogenous base of Mon 6 is guanine, the nitrogenous base of Mon 7 is guanine and the nitrogenous base of Mon 8 is adenine; - an anterior flanking region Mon a4 -Mon a3 -Mon a2 -Mon a1 - bound to the monomer Mon 1 and a posterior flanking region -Mon b1 -Mon b2 -Mon b3 -Mon b4 bound to the monomer Mon 8 of said structure, wherein Mon a1 to Mon a4 and Mon b1 to Mon b4 are monomers of a nucleic acid or of a chemical analogue of nucleic acid and comprise a nitrogenous base, such that: i. the nitrogenous bases from Mon a1 to Mon a4 are independently selected from the following group: A, C, G, T and U; ii. the nitrogenous base of Mon b1 is complementary to the nitrogenous base of Mon a1; iii. the nitrogenous base of Mon b2 is complementary to the nitrogenous base of Mon 32; iv. the nitrogenous base of Mon b3 is complementary to the nitrogenous base of Mon a3; v. the nitrogenous base of Mon b4 is complementary to the nitrogenous base of Mon a4; wherein the complementarity rules to which these respective pairings of Mon a1 to Mon a4 with Mon b1 to Mon b4 are subjected are: A is complementary to T or U; C is complementary to G; G is complementary to C or U; T is complementary to A; U is complementary to A or G; and wherein the nitrogenous bases of the 4 monomers of the anterior flanking region closest to Mon 1 are paired with the nitrogenous bases of the 4 monomers of the posterior flanking region so that the sequence structure Mon 1 -Mon 2 -Mon 3 -Mon 4 -Mon 5 -Mon 6 -Mon 7 -Mon 8 forms a single-stranded terminal loop closing a double-stranded stem formed by the flanking regions with said paired monomers; or the enantiomer of said aptamer. i. the nitrogenous bases from Mon a1 to Mon a4 are independently selected from the following group: A, C, G, T and U; ii. the nitrogenous base of Mon b1 is complementary to the nitrogenous base of Mon a1; iii. the nitrogenous base of Mon b2 is complementary to the nitrogenous base of Mon 32; iv. the nitrogenous base of Mon b3 is complementary to the nitrogenous base of Mon a3; v. the nitrogenous base of Mon b4 is complementary to the nitrogenous base of Mon a4;