Jul 2026· Journal of Medicinal Chemistry· Vol 69, pp. 16878-16895· 0 citations· 33 references
Medicine
TL;DR
This work pioneers the development of CA-targeted degraders, providing a framework for next-generation anti-HIV therapies with high potency and resistance barriers, via a proteasome-driven pathway.
Abstract
The escalating prevalence of HIV-1 drug-resistant variants and the toxicity limitations of conventional antiretroviral therapies necessitate therapeutic strategies with novel mechanisms of action. This study focuses on HIV-1 capsid (CA), an essential replication-related viral protein. We developed CA-targeted proteolysis-targeting chimera (PROTAC) degraders by conjugating PF74-derived CA ligand IIA-4 with VHL E3 ligase ligand. Among these, VHL-3 exhibited potent anti-HIV-1 activity in MT-4 cells (EC50 = 3.0 ± 1.5 nM), a 300-fold improvement over PF74. Mechanistic studies confirmed VHL-3 dose- and time-dependently reduced CA levels in HEK293T cells (early stage, DC50 = 812 nM; late stage, DC50 = 252 nM) via a proteasome-driven pathway. Notably, it effectively degraded clinically relevant CA-resistant mutants (N74D, K70R). This work pioneers the development of CA-targeted degraders, providing a framework for next-generation anti-HIV therapies with high potency and resistance barriers.
ABSTRACT Influenza A virus (IAV) poses a serious threat to public health due to its high mutability and rapid transmissibility. The viral nucleoprotein (NP), a highly conserved and essential component, has emerged as an ideal target for antiviral therapies. However, its biological function has proven challenging to modulate with conventional drugs, and no NP-targeting therapeutics have reached the market so far. Here, we report the development and application of an aptamer-based proteolysis-targeting chimera (PROTAC) for the targeted degradation of IAV NP. Utilizing the Direct-to-Biology (D2B) platform, we efficiently screened and identified NP-PROTAC#4 as a functional candidate. Subsequently, we developed a lipid nanoparticle (LNP) formulation of NP‑PROTAC#4 (LNP@NP‑PROTAC#4) for effective intracellular delivery. Importantly, LNP@NP-PROTAC#4 demonstrated potent antiviral activity both in vitro and in vivo. Mechanistically, NP-PROTAC#4 exerts its antiviral effects by targeting and degrading NP via the ubiquitin-proteasome system. In conclusion, our findings provide the first evidence that NP-targeted PROTAC degrader exhibits therapeutic effects, proposing a novel therapeutic strategy for IAV.
ABSTRACT Diseases caused by picornaviruses pose a serious threat to society due to their high contagiousness and widespread prevalence. Beyond the poliovirus vaccine, antiviral therapeutics remain unavailable for most picornaviral infections. Moreover, existing inhibitors under development generally exhibit narrow‐spectrum activity and low barriers to resistance owing to the high mutability of RNA viral proteins. To address these issues, this study constructed a proteolysis‐targeting chimera (PROTAC) targeting the 3C protease (3CPro) — a key viral enzyme essential for picornavirus protein processing, host shutoff, and immune suppression. In enterovirus 71 (EV71), a representative member of the picornavirus family, experimental results showed that PROTAC molecule effectively inhibits viral replication through a dual mechanism of action: directly inhibiting the catalytic function of the 3CPro and inducing its degradation via the ubiquitin‐proteasome pathway. Moreover, this PROTAC molecule not only demonstrated effective degradation of previously reported and AI‐predicted potential drug‐resistant EV71 mutants, but also exhibited degradation activity against 3CPro from multiple picornaviruses, indicating its potential for broad‐spectrum antiviral activity. By integrating multidisciplinary approaches, this work demonstrates that targeted protein degradation can effectively induce the degradation of 3CPro in picornaviruses, supporting the development of resistance‐resistant, broad‐spectrum antiviral agents and highlighting their potential to address evolving viral threats.
Weilong Deng, Jun-Yu Chen, Yingyue Pang et al.· Advancement of science· 0 citations
Antiretroviral therapy (ART) strategies against HIV-1 have been successful in suppressing HIV-1 replication and preventing disease progression. However, drug-resistance development, side-effects and life-long adherence of current drugs have driven the development of novel inhibitors against HIV-1. Inhibition of capsid production by targeting the highly conserved capsid protein (CA) has shown to be promising in blocking viral replication. Here, we developed a capsid-targeting biological composed of a single-domain Llama VHH that binds CA, fused to human IgG1 Fc to activate TRIM21-mediated degradation. This anti-capsid biological (aCA-Fc) efficiently bound CA. When expressed intracellularly aCA-Fc completely blocked HIV-1 production by degrading the capsid precursor Gag. Moreover, transfection of purified aCA-Fc during HIV-1 infection also resulted in degradation of Gag. aCA-Fc inhibited HIV-1 replication to similar extent as clinically approved capsid inhibitor lenacapavir (LEN). Interestingly, aCA-Fc didn't interfere with viral entry and reverse transcription, but eliminated newly produced HIV-1 Gag via TRIM21-mediated proteasomal degradation, even when added after infection. Gag production was restored by proteasome inhibition, introduction of the H433A mutation in the Fc domain and by TRIM21 knockdown using siRNA. These findings suggest that capsid-targeting biologicals, upon effective intracellular delivery, could serve as novel therapeutic strategies for viral suppression through intracellular protein degradation.
F. M. Stel, Charlotte E J Verkuijlen, E. Zijlstra-Willems et al.· Communications Biology· 1 citation
Antiretroviral therapy (ART) has proven effective in suppressing HIV-1 replication, but further development of HIV-1 inhibitors is continually driven by the challenge of drug resistance and viral adaptation. The HIV-1 capsid is a promising target for treatment due to its high sequence conservation as well as its crucial role in the viral life cycle. Recently, we have developed a novel capsid-targeting biologic that prevents HIV-1 replication by efficient degradation of newly synthesized capsid. Here, we have investigated the sensitivity to viral escape as well as the breadth of this biologic against HIV-1 subtypes. The capsid-targeting biologic efficiently blocked replication of different primary HIV-1 isolates, and continuous exposure of these viruses to the biologic resulted in viral breakthrough of two out of ten primary HIV-1 isolates tested. Notably, the breakthrough variants did not have amino acid changes in the nanobody epitope but primarily in the matrix region. The breakthrough variants remained sensitive to the biologic albeit to a lesser extent. In the absence of the biologic, breakthrough variants showed increased replication kinetics when compared to their parental virus, suggesting that adaption to the biologic is likely due to the increased viral production and that the target area of the biologic is too conserved for actual escape. This is further underscored by the broad specificity of the biologic as importantly the biologic blocked infection of different HIV-1 subtypes that occur worldwide (A, B, C, D, CRF01_AE, CRF02_AG). These results demonstrate the broad neutralization potential of anti-capsid biologics with a high barrier to resistance, making capsid-targeting inhibitors important for novel antiretroviral drug strategies worldwide.
F. M. Stel, E. Zijlstra-Willems, A. V. Nuenen et al.· International Journal of Mol...· 0 citations
HIV-1 release from infected cells requires coordinated action of the viral Gag protein and the host endosomal sorting complexes required for transport (ESCRT) machinery. How innate immunity regulates ESCRT function to limit viral egress remains unclear. Here, we show that MITD1, a cell type-specific interferon-stimulated gene, is a potent inhibitor of ESCRT-dependent HIV-1 budding. MITD1 engages ESCRT-III subunits CHMP1B and CHMP4B, driving their incorporation into aggregates and impairing ESCRT-III assembly during HIV-1 budding. This disrupts the final steps of virion release, causing an accumulation of immature particles at the plasma membrane. MITD1 overexpression reduces HIV-1 release from cell lines, primary peripheral blood mononuclear cells (PBMCs), and human microglia, while sparing the release of ESCRT-independent viruses. These findings establish MITD1 as an interferon-stimulated restriction factor that limits HIV-1 egress by perturbing ESCRT-III assembly.
Jim Zoladek, Marion Cannac, Claire Lacouture et al.· Cell Reports· 0 citations
It is demonstrated that nanobodies targeting the PLpro/ISG15 interface can achieve synergistic antiviral and immunomodulatory effects, providing a proof-of-concept for a novel therapeutic approach to combat SARS-CoV-2 and potentially other emerging coronaviruses.
Guo-Long Liu, Jiantao Chen, Fang Wu et al.· Journal of Virology· 0 citations