HIV Integrase Inhibitors Block Replication of Alpha-, Beta-, and Gammaherpesviruses

The catalytic site of the HIV integrase is contained within an RNase H-like fold, and numerous drugs have been devel- oped that bind to this site and inhibit its activity. Herpes simplex virus (HSV) encodes two proteins with potential RNase H-like folds, the infected cell protein 8 (ICP8) DNA-binding protein, which is necessary for viral DNA replication and exhibits recom- binase activity in vitro, and the viral terminase, which is essential for viral DNA cleavage and packaging. Therefore, we hypothe- sized that HIV integrase inhibitors might also inhibit HSV replication by targeting ICP8 and/or the terminase. To test this, we evaluated the effect of 118-D-24, a potent HIV integrase inhibitor, on HSV replication. We found that 118-D-24 inhibited HSV-1 replication in cell culture at submillimolar concentrations. To identify more potent inhibitors of HSV replication, we screened a panel of integrase inhibitors, and one compound with greater anti-HSV-1 activity, XZ45, was chosen for further analysis. XZ45 significantly inhibited HSV-1 and HSV-2 replication in different cell types, with 50% inhibitory concentrations that were ap- proximately 1 M, but exhibited low cytotoxicity, with a 50% cytotoxic concentration greater than 500 M. XZ45 blocked HSV viral DNA replication and late gene expression. XZ45 also inhibited viral recombination in infected cells and ICP8 recombinase activity in vitro. Furthermore, XZ45 inhibited human cytomegalovirus replication and induction of Kaposi's sarcoma herpesvi- rus from latent infection. Our results argue that inhibitors of enzymes with RNase H-like folds may represent a general antiviral strategy, which is useful not only against HIV but also against herpesviruses. IMPORTANCE The herpesviruses cause considerable morbidity and mortality. Nucleoside analogs have served as effective antivi- ral agents against the herpesviruses, but resistance can arise through viral mutation. Second-line anti-herpes drugs have limita- tions in terms of pharmacokinetic properties and/or toxicity, so there is a great need for additional drugs for treatment of her- pesviral infections. This study showed that the HIV integrase inhibitors also block herpesviral infection, raising the important potential of a new class of anti-herpes drugs and the prospect of drugs that combat both HIV and the herpesviruses.