3-Hydroxyphthalic Anhydride-Modified Chicken Ovalbumin as a Potential Candidate Inhibits SARS-CoV-2 Infection by Disrupting the Interaction of Spike Protein With Host ACE2 Receptor

Phenothiazines Inhibit SARS-CoV-2 Entry through Targeting Spike Protein

Novel coronavirus disease 2019 (COVID-19), a respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has brought an unprecedented public health crisis and continues to threaten humanity due to the persistent emergence of new variants. Therefore, developing more effective and broad-spectrum therapeutic and prophylactic drugs against infection by SARS-CoV-2 and its variants, as well as future emerging CoVs, is urgently needed. In this study, we screened several US FDA-approved drugs and identified phenothiazine derivatives with the ability to potently inhibit the infection of pseudotyped SARS-CoV-2 and distinct variants of concern (VOCs), including B.1.617.2 (Delta) and currently circulating Omicron sublineages XBB and BQ.1.1, as well as pseudotyped SARS-CoV and MERS-CoV. Mechanistic studies suggested that phenothiazines predominantly inhibited SARS-CoV-2 pseudovirus (PsV) infection at the early stage and potentially bound to the spike (S) protein of SARS-CoV-2, which may prevent the proteolytic cleavage of the S protein, thereby exhibiting inhibitory activity against SARS-CoV-2 infection. In summary, our findings suggest that phenothiazines can serve as a potential broad-spectrum therapeutic drug for the treatment of SARS-CoV-2 infection as well as the infection of future emerging human coronaviruses (HCoVs).

Identification of phytochemicals in Qingfei Paidu decoction for the treatment of coronavirus disease 2019 by targeting the virus-host interactome

Qingfei Paidu decoction (QFPDD) has been clinically proven to be effective in the treatment of coronavirus disease 2019 (COVID-19). However, the bioactive components and therapeutic mechanisms remain unclear. This study aimed to explore the effective components and underlying mechanisms of QFPDD in the treatment of COVID-19 by targeting the virus-host interactome and verifying the antiviral activities of its active components in vitro. Key active components and targets were identified by analysing the topological features of a compound-target-pathway-disease regulatory network of QFPDD for the treatment of COVID-19. The antiviral activity of the active components was determined by a live virus infection assay, and possible mechanisms were analysed by pseudotyped virus infection and molecular docking assays. The inhibitory effects of the components tested on the virus-induced release of IL-6, IL-1β and CXCL-10 were detected by ELISA. Three components of QFPDD, oroxylin A, hesperetin and scutellarin, exhibited potent antiviral activities against live SARS-CoV-2 virus and HCoV-OC43 virus with IC₅₀ values ranging from 18.68 to 63.27 μM. Oroxylin A inhibited the entry of SARS-CoV-2 pseudovirus into target cells and inhibited SARS-CoV-2 S protein-mediated cell-cell fusion by binding with the ACE2 receptor. The active components of QFPDD obviously inhibited the IL-6, IL-1β and CXCL-10 release induced by the SARS-CoV-2 S protein. This study supports the clinical application of QFPDD and provides an effective analysis method for the in-depth study of the mechanisms of traditional Chinese medicine (TCM) in the prevention and treatment of COVID-19.

UHRF1 Suppresses HIV-1 Transcription and Promotes HIV-1 Latency by Competing with p-TEFb for Ubiquitination-Proteasomal Degradation of Tat

HIV-1 remains incurable due to viral reservoirs, which lead to durably latent HIV infection. Identifying novel host factors and deciphering the molecular mechanisms involved in the establishment and maintenance of latency are critical to discover new targets for the development of novel anti-HIV agents. Here, we show that ubiquitin-like with PHD and RING finger domain 1 (UHRF1) modulates HIV-1 5'-long terminal repeat (LTR)-driven transcription of the viral genome as a novel HIV-1 restriction factor. Correspondingly, UHRF1 depletion reversed the latency of HIV-1 proviruses. Mechanistically, UHRF1 competed with positive transcription factor b (p-TEFb) for the binding to the cysteine-rich motifs of HIV-1 Tat via its TTD, PHD, and RING finger domains. Furthermore, UHRF1 mediated K48-linked ubiquitination and proteasomal degradation of Tat in RING-dependent ways, leading to the disruption of Tat/cyclin T1/CDK9 complex and consequential impediment of transcription elongation. In summary, our findings revealed that UHRF1 is an important mediator of HIV-1 latency by controlling Tat-mediated transcriptional activation, providing novel insights on host-pathogen interaction for modulating HIV-1 latency, beneficial for the development of anti-AIDS therapies. IMPORTANCE HIV-1 latency is systematically modulated by host factors and viral proteins. In our work, we identified a critical role of host factor ubiquitin-like with PHD and RING finger domain 1 (UHRF1) in HIV-1 latency via the modulation of the viral protein Tat stability. By disrupting the Tat/cyclin T1/CDK9 complex, UHRF1 promotes the suppression of HIV-1 transcription and maintenance of HIV-1 latency. Our findings provide novel insights in controlling Tat expression via host-pathogen interaction for modulating HIV-1 latency. Based on our results, modulating UHRF1 expression or activity by specific inhibitors is a potential therapeutic strategy for latency reversal in HIV-1 patients.