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Debnath, A. K.

Publications and source records attributed to Debnath, A. K..

3 recordsLinked to original sources

A First-in-Class Dual Degrader of Bcl-2/Bcl-xL Reverses HIV Latency and Eliminates Ex Vivo Reservoirs

The persistence of latent HIV-1 proviruses in CD4+ T cells is a major obstacle to curing HIV. The "shock and kill" strategy involves reversing latency with latency-reversing agents (LRAs) and selectively inducing cell death in infected cells. However, current LRAs have shown limited efficacy in eliminating the ex vivo HIV reservoir. We repurposed PZ703b, a pro-apoptotic protein degrader initially developed for anti-leukemia therapy, to target HIV eradication. PZ703b induced degradation of Bcl-2 and Bcl-xL, activating the non-canonical NF-kB pathway and caspases cascade, resulting in latency reversal and selective apoptosis of infected cells. Treatment of ex vivo CD4+ T cells from ART-suppressed HIV-1 patients achieved a [~]50% reduction in the replication-competent reservoir. Our study provides proof-of-concept for using protein degraders to reverse HIV latency and induce cell death, highlighting PZ703bs potential in HIV cure strategies. This approach may pave the way for novel therapeutic interventions aimed at eliminating the HIV-inducible reservoir.

molecular biology↗

Discovery of highly potent small molecule pan-coronavirus fusion inhibitors

The unprecedented pandemic of COVID-19, caused by a novel coronavirus, SARS-CoV-2, has led to massive human suffering, death, and economic devastation worldwide. The virus is mutating fast to more transmissible and infectious variants. The Delta variant (B.1.617.2), initially identified in India, and the omicron variant (BA.4 and BA.5) have spread worldwide. In addition, recently alarming antibody evasive SARS-CoV-2 subvariants, BQ and XBB, have been reported. These new variants may pose a substantial challenge to controlling the spread of this virus. Therefore, the continued development of novel drugs having pan-coronavirus inhibition to treat and prevent infection of COVID-19 is urgently needed. These drugs will be critically important in dealing with new pandemics that will emerge in the future. We report the discovery of several highly potent small molecule pan-coronavirus inhibitors. One of which, NBCoV63, showed low nM potency against SARS-CoV-2 (IC50: 55 nM), SARS-CoV (IC50: 59 nM), and MERS-CoV (IC50: 75 nM) in pseudovirus-based assays with excellent selectivity indices (SI: as high as > 900) demonstrating its pan-coronavirus inhibition. NBCoV63 showed equally effective antiviral potency against SARS-CoV-2 mutant (D614G) and several variants of concerns (VOCs) such as B.1.617.2 (Delta), B.1.1.529/BA.1 and BA.4/BA.5 (Omicron) and K417T/E484K/N501Y (Gamma). NBCoV63 also showed similar efficacy profiles to Remdesivir against authentic SARS-CoV-2 (Hong Kong strain) and two of its variants (Delta and Omicron) by plaque reduction in Calu3 cells. Additionally, we show that NBCoV63 inhibits virus-mediated cell-to-cell fusion in a dose-dependent manner. Furthermore, the Absorption, distribution, metabolism, and excretion (ADME) data of NBCoV63 demonstrated drug-like properties.

pharmacology and toxicology↗

Stapled peptides based on Human Angiotensin-Converting Enzyme 2 (ACE2) potently inhibit SARS-CoV-2 infection in vitro

SARS-CoV-2 uses human angiotensin-converting enzyme 2 (ACE2) as the primary receptor to enter host cells and initiate the infection. The critical binding region of ACE2 is a [~]30 aa long helix. Here we report the design of four stapled peptides based on the ACE2 helix, which is expected to bind to SARS-CoV-2 and prevent the binding of the virus to the ACE2 receptor and disrupt the infection. All stapled peptides showed high helical contents (50-94% helicity). On the contrary, the linear control peptide NYBSP-C showed no helicity (19%). We have evaluated the peptides in a pseudovirus based single-cycle assay in HT1080/ACE2 and human lung cells A549/ACE2, overexpressing ACE2. Three of the four stapled peptides showed potent antiviral activity in HT1080/ACE2 (IC50: 1.9 - 4.1 {micro}M) and A549/ACE2 cells (IC50: 2.2 - 2.8 {micro}M). The linear peptides NYBSP-C and the double-stapled peptide StRIP16, used as controls, showed no antiviral activity. Most significantly, none of the stapled peptides show any cytotoxicity at the highest dose tested. We also evaluated the antiviral activity of the peptides by infecting Vero E6 cells with the replication-competent authentic SARS-CoV-2 (US_WA-1/2020). NYBSP-1 was the most efficient preventing the complete formation of cytopathic effects (CPEs) at an IC100 17.2 {micro}M. NYBSP-2 and NYBSP-4 also prevented the formation of the virus-induced CPE with an IC100 of about 33 {micro}M. We determined the proteolytic stability of one of the most active stapled peptides, NYBSP-4, in human plasma, which showed a half-life (T1/2) of >289 min.

pharmacology and toxicology↗