Herpes simplex virus 1 (HSV-1) and Influenza A viruses (IAV) induce Z-form nucleic acid Binding Protein 1 (ZBP1)-initiated cell death^1-8. ZBP1 is activated by Z-RNA^1,7,9, and the Z-RNAs which trigger ZBP1 during HSV-1 and IAV infections were assumed to be of viral origin¹. However, we show here that host cell-encoded Z-RNAs are major and sufficient ZBP1 activating ligands following infection by these two human pathogens. The majority of cellular Z-RNAs mapped to intergenic endogenous retroelements (EREs) embedded within abnormally long 3' extensions of host cell mRNAs. These aberrant host cell transcripts arose as a consequence of Disruption of Transcription Termination (DoTT), a virus-driven phenomenon which disables Cleavage and Polyadenylation Specificity Factor (CPSF)-mediated 3' processing of nascent pre-mRNAs^10-15. Mutant viruses lacking ICP27 or NS1, the virus-encoded proteins responsible for inhibiting CPSF and triggering DoTT^13,15, failed to induce host cell Z-RNA accrual and were attenuated in their ability to stimulate ZBP1. Ectopic expression of HSV-1 ICP27 or IAV NS1, or pharmacological blockade of CPSF activity, induced accumulation of host cell Z-RNAs and activated ZBP1. These results demonstrate that DoTT-generated cellular Z-RNAs are bona fide ZBP1 ligands, and position ZBP1-activated cell death as a host response to counter viral disruption of the cellular transcriptional machinery.

RNA viruses, in pursuit of genome miniaturization, tend to employ cellular proteins to facilitate their replication. HIV-1, one of the most well-studied retroviruses, is not an exception. There is numerous evidence that the exploitation of cellular machinery relies on nucleic acid-protein and protein-protein interactions. Apart from Vpr, Vif, and Nef proteins that are known to regulate cellular functioning via interaction with cell components, another viral protein, integrase, appears to be crucial for proper virus-cell dialog at different stages of the viral life cycle. The goal of this review is to summarize and systematize existing data on known cellular partners of HIV-1 integrase and their role in the HIV-1 life cycle.

The search for compounds that can inhibit the interaction of certain viral proteins with their cellular partners is a promising trend in the development of antiviral drugs. We have previously shown that binding of HIV-1 integrase with human Ku70 protein is essential for viral replication. Here, we present a novel, cheap, and fast assay to search for inhibitors of these proteins’ binding based on the usage of genetically encoded fluorescent tags linked to both integrase and Ku70. Using this approach, we have elucidated structure-activity relationships for a set of oligonucleotide conjugates with eosin and shown that their inhibitory activity is primarily achieved through interactions between the conjugate nucleic bases and integrase. Molecular modeling of HIV-1 integrase in complex with the conjugates suggests that they can shield E212/L213 residues in integrase, which are crucial for its efficient binding to Ku70, in a length-dependent manner. Using the developed system, we have found the 11-mer phosphorothioate bearing 3’-end eosin-Y to be the most efficient inhibitor among the tested conjugates.