DNA damage enhances integration of HIV-1 into macrophages by overcoming integrase inhibition.

Retrovirology. 2013 Feb 21;10:21.

Koyama T, Sun B, Tokunaga K, Tatsumi M, Ishizaka Y.

Department of Intractable Diseases, National Center for Global Health and Medicine, 1-21-1 Toyama, 162-8655, Shinjuku-ku, Tokyo, Japan.



BACKGROUND: The prevention of persistent human immunodeficiency virus type 1 (HIV-1) infection requires the clarification of the mode of viral transduction into resting macrophages. Recently, DNA double-strand breaks (DSBs) were shown to enhance infection by D64A virus, which has a defective integrase catalytic activity (IN-CA). However, the mechanism by which DSBs upregulate viral transduction was unclear. Here we analyzed the roles of DSBs during IN-CA-independent viral transduction into macrophages.

RESULTS: We used cellular systems with rare-cutting endonucleases and found that D64A virus integrated efficiently into the sites of artificially induced DSBs. This IN-CA-independent viral transduction was blocked by an inhibitor of ataxia telangiectasia mutated protein (ATM) but was resistant to raltegravir (RAL), an inhibitor of integrase activity during strand transfer. Moreover, Vpr, an accessory gene product of HIV-1, induced DSBs in resting macrophages and significantly enhanced the rate of IN-CA-independent viral transduction into macrophages with concomitant production of secondary viruses.

CONCLUSION: DSBs contribute to the IN-CA-independent viral infection of macrophages, which is resistant to RAL. Thus, the ATM-dependent cellular pathway and Vpr-induced DNA damage are novel targets for preventing persistent HIV-1 infection.

PMID: 23432899



Figure 1. DSB provides a platform for integration of viral DNA without integrase catalytic activity.

We observed that the integration of HIV-1 DNA into the host genome was enhanced by DNA damage (DSB:DNA double-strand break) in a manner independent of the catalytic activity of integrase (IN-CA). The DSB-induced IN-CA–independent viral integration was not negligible, because our data revealed that up to 0.2~3.8% of total viral transduction was resistant to an integrase inhibitor, in MAGIC5 cells and MT-4 cells, respectively. Given that the full-length provirus DNA was identified in the DSB-sites and the secondary virus was generated after the IN-CA independent viral integration, data strongly suggest that the functional provirus virus DNA can integrate into the DSB-sites. It is important to clarify how viral DNA is integrated into the DSB-sites. One possible hypothesis is that DSB-dependent cellular cascade recruits the reverse-transcribed viral DNA to the DSB-site, and identification of involved cellular factors is critical as a further direction of research. Additionally, we observed that Vpr, an accessory gene product of HIV-1, mimicked DNA damage, and promoted the IN-CA–independent integration of viral DNA. An additional issue is to understand how Vpr causes the IN-CA independent viral integration, and understanding the mode of Vpr-induced DSB would provide a novel approach especially for controlling viral infection into resting macrophages.

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