HIV-I integrase inhibitors: Past, present, and future

Abstract

HIV-1 integrase (IN) contains 288 amino acids and belongs to a superfamily of polynucleotide transferases that include Mu transposase, RNase H, and RuvC. The functional domains of IN are discussed in the chapter. The N terminus contains the highly conserved HHCC motif that binds to a molecule of Zn2+ and it is involved in dimerization or multimerization. The catalytic core contains the characteristic three acidic residues known as the DDE motif that is involved in all the catalytic reactions carried out by IN. These residues bind divalent metals and are highly conserved in the polynucleotidyl transferases superfamily. Structural and biochemical understanding of the enzyme has led to the development of in vitro assays aimed at identifying IN inhibitors. Such assays utilize synthetic oligonucleotides, corresponding to the U5 end of the viral long terminal repeats (LTR), recombinant IN, and divalent metal cofactor (Mn2+ or Mg2+). It is generally believed that IN remains tightly bound to viral LTR DNA both in vivo and throughout the course of the integration reaction in vitro. Inhibition of HIV-1 replication at both the early and late stages of the viral life cycle by single-chain antibody against viral IN has also been discussed in the chapter. In addition, peptide antisera against selected regions in HIV-1 and HIV-2 RT and IN were shown to inhibit IN-mediated cleavage of an HIV-1 DNA oligonucleotide substrate in a 3' processing assay, while antiRT or normal sera had no effect. None of the RT sera inhibited RT activity.