Suppression of HIV-1 Integration by Targeting HIV-1 Integrase for Degradation with A Chimeric Ubiquitin Ligase.

Human immunodeficiency virus (HIV) attacks human immune system and causes life-threatening acquired immune deficiency syndrome (AIDS). Treatment with combination antiretroviral therapy (cART) could inhibit virus growth and slow progression of the disease, however, at the same time posing various adverse effects. Host ubiquitin-proteasome pathway (UPP) plays important roles in host immunity against pathogens including viruses by inducing degradation of viral proteins. Previously a series of methods for retargeting substrates for ubiquitin-proteasome degradation have been successfully established. In this study, we attempted to design and construct artificial chimeric ubiquitin ligases (E3s) based on known human E3s in order to manually target HIV-1 integrase for ubiquitin proteasome pathway-mediated degradation. Herein, a series of prototypical chimeric E3s have been designed and constructed, and original substrate-binding domains of these E3s were replaced with host protein domains which interacted with viral proteins. After functional assessment screening, 146LI was identified as a functional chimeric E3 for HIV-1 NL4-3 integrase. 146LI was then further optimized to generate 146LIS (146LI short) which has been shown to induce Lys48-specific polyubiquitination and reduce protein level of HIV-1 NL4-3 integrase more effectively in cells. Lymphocyte cells with 146LIS knock-in generated by CRISPR/Cas-mediated homology-directed repair (HDR) showed remarkably decreased integration of HIV-1 NL4-3 viral DNAs and reduced viral replication without obvious cell cytotoxicity. Our study successfully obtained an artificial chimeric E3 which can induce Lys48-specific polyubiquitination and proteasome-mediated degradation of HIV-1 NL4-3 integrase, thus effectively inhibiting viral DNA integration and viral replication upon virus infection.