Anti-HIV-1 integrase drugs: how far from the shelf?

Chemotherapy of HIV-1 infection/AIDS currently employs inhibitors of two products of the viral pol gene, the reverse transcriptase and protease enzymes. However, a third product of the pol gene is essential for retroviral multiplication, the integrase. As no cellular homologue of HIV integrase has been described, potential inhibitors could be relatively nontoxic. Development of HIV-1 integrase inhibitors could have favorable implication for combination therapy, including potential synergy with currently available inhibitors, as well as prevention of the chronic carrier state and the emergence of resistant mutants. Although several classes of putative integrase inhibitors that been described, still no clinically useful anti-integration drugs are available. It is the structural and functional complexity of the integration process together with the limitations of the available in vitro assays that has made it problematic to develop inhibitors of the HIV integrase. In this review we summarize current knowledge concerning the biology of this enzyme and of the integration process, and discuss major classes representatives of integrase inhibitors considering the obstacles to the development of true anti-integrase drugs.