The cyclophilin A-binding loop of the capsid regulates the human TRIM5α sensitivity of nonpandemic HIV-1.

The rather few cases of humans infected by HIV-1 N, O, or P raise the question of their incomplete adaptation to humans. We hypothesized that early postentry restrictions may be relevant for the impaired spread of these HIVs. One of the best-characterized species-specific restriction factors is TRIM5α. HIV-1 M can escape human (hu) TRIM5α restriction by binding cyclophilin A (CYPA, also known as PPIA, peptidylprolyl isomerase A) to the so-called CYPA-binding loop of its capsid protein. How non-M HIV-1s interact with huTRIM5α is ill-defined. By testing full-length reporter viruses (Δ env) of HIV-1 N, O, P, and SIVgor (simian IV of gorillas), we found that in contrast to HIV-1 M, the nonpandemic HIVs and SIVgor showed restriction by huTRIM5α. Work to identify capsid residues that mediate susceptibility to huTRIM5α revealed that residue 88 in the capsid CYPA-binding loop was important for such differences. There, HIV-1 M uses alanine to resist, while non-M HIV-1s have either valine or methionine, which avail them for huTRIM5α. Capsid residue 88 determines the sensitivity to TRIM5α in an unknown way. Molecular simulations indicated that capsid residue 88 can affect trans-to-cis isomerization patterns on the capsids of the viruses we tested. These differential CYPA usages by pandemic and nonpandemic HIV-1 suggest that the enzymatic activity of CYPA on the viral core might be important for its protective function against huTRIM5α.

Longitudinal deep sequencing informs vector selection and future deployment strategies for transmissible vaccines.

Vaccination is a powerful tool in combating infectious diseases of humans and companion animals. In most wildlife, including reservoirs of emerging human diseases, achieving sufficient vaccine coverage to mitigate disease burdens remains logistically unattainable. Virally vectored "transmissible" vaccines that deliberately spread among hosts are a potentially transformative, but still theoretical, solution to the challenge of immunising inaccessible wildlife. Progress towards real-world application is frustrated by the absence of frameworks to guide vector selection and vaccine deployment prior to major in vitro and in vivo investments in vaccine engineering and testing. Here, we performed deep sequencing on field-collected samples of Desmodus rotundus betaherpesvirus (DrBHV), a candidate vector for a transmissible vaccine targeting vampire bat-transmitted rabies. We discovered 11 strains of DrBHV that varied in prevalence and geographic distribution across Peru. The phylogeographic structure of DrBHV strains was predictable from both host genetics and landscape topology, informing long-term DrBHV-vectored vaccine deployment strategies and identifying geographic areas for field trials where vaccine spread would be naturally contained. Multistrain infections were observed in 79% of infected bats. Resampling of marked individuals over 4 years showed within-host persistence kinetics characteristic of latency and reactivation, properties that might boost individual immunity and lead to sporadic vaccine transmission over the lifetime of the host. Further, strain acquisitions by already infected individuals implied that preexisting immunity and strain competition are unlikely to inhibit vaccine spread. Our results support the development of a transmissible vaccine targeting a major source of human and animal rabies in Latin America and show how genomics can enlighten vector selection and deployment strategies for transmissible vaccines.

Sublethal effects of parasitism on ruminants can have cascading consequences for ecosystems.

Parasitic infections are common, but how they shape ecosystem-level processes is understudied. Using a mathematical model and meta-analysis, we explored the potential for helminth parasites to trigger trophic cascades through lethal and sublethal effects imposed on herbivorous ruminant hosts after infection. First, using the model, we linked negative effects of parasitic infection on host survival, fecundity, and feeding rate to host and producer biomass. Our model, parameterized with data from a well-documented producer­caribou­helminth system, reveals that even moderate impacts of parasites on host survival, fecundity, or feeding rate can have cascading effects on ruminant host and producer biomass. Second, using meta-analysis, we investigated the links between helminth infections and traits of free-living ruminant hosts in nature. We found that helminth infections tend to exert negative but sublethal effects on ruminant hosts. Specifically, infection significantly reduces host feeding rates, body mass, and body condition but has weak and highly variable effects on survival and fecundity. Together, these findings suggest that while helminth parasites can trigger trophic cascades through multiple mechanisms, overlooked sublethal effects on nonreproductive traits likely dominate their impacts on ecosystems. In particular, by reducing ruminant herbivory, pervasive helminth infections may contribute to a greener world.

Endovascular Repair of One-hundred Urgent and Emergent free or Contained Thoraco-abdominal Aortic Aneurysms Ruptures. An International Multi-Center Trans-Atlantic experience.

OBJECTIVE: To analyze the outcomes of urgent/emergent endovascular aortic repair of patients with free/contained ruptured thoracoabdominal aortic aneurysms (rTAAA). BACKGROUND: Endovascular repair of rTAAA has been scarcely described in emergent setting. METHODS: An international multicenter retrospective observational study (ClinicalTrials.govID:NCT05956873) from January-2015 to January-2023 in 6 European and 1 United States Vascular Surgery Centers. Primary end-points were technical success, 30-day and/or in-hospital mortality and follow-up survival. RESULTS: A total of 100 rTAAA patients were included (75 male; mean age 73 y). All patients (86 contained and 14 free ruptures) were symptomatic and treated within 24-hours from diagnosis: multi-branched off-the-shelf devices (Zenith t-branch,Cook Medical Inc.Bjaeverskov,Denmark) in 88 patients, physician-modified endografts in 8, patient-specific device or parallel grafts in two patients each. Primary technical success was achieved in 89 patients and 30-day and/or in-hospital mortality was 24%. Major adverse events (MAEs) occurred in 34% of patients (permanent dialysis and paraplegia in 4 and 8 patients, respectively). No statistical differences were detected in mortality rates between free and contained ruptured patients (43%vs.21%; P =0.075). Multivariate analysis revealed contained rupture favoring technical success (Odd-Ratio10.1;95%Confidence-Interval:3.0-33.6; P =<0.001). MAEs (OR9.4;95%C-I:2.8-30.5; P =<0.001) and pulmonary complications (OR11.3;95%CI:3.0-41.5; P =<0.001) were independent risk factors for 30-day and/or in-hospital mortality. Median follow-up time was 13 months (interquartile range 5-24); 1-year survival rate was 65%. Aneurysm diameter>80 mm (Hazard-Ratio:2.0;95%CI:1.0-30.5; P =0.037), technical failure (HR:2.6;95%CI:1.1-6.5; P =0.045) and pulmonary complications (HR:3.0;95%CI:1.2-7.9; P =0.021) were independent risk factors for follow-up mortality. CONCLUSION: Endovascular repair of rTAAA shows high technical success; the presence of free rupture alone appear not to correlate with early mortality. Effective prevention/management of post-operative complications is crucial for survival.

Outcome of the Be Graft Bridging Stent in Fenestrated Endovascular Aortic Repair in a High-Volume Single Center and an Overview of Current Evidence.

OBJECTIVE: Fenestrated endovascular aneurysm repair (FEVAR) has become one of the standard treatment options for complex abdominal aortic aneurysms (cAAAs) and thoraco-abdominal aortic aneurysms (TAAAs). Despite technological advances in the main endograft design, the lack of dedicated bridging stent-grafts (BSGs) is still the Achilles heel of the procedure. The aim of this study was to evaluate the mid-term outcomes of the BeGraft stent-graft as a dedicated bridging stent for FEVAR and to review the current evidence in literature. METHODS: Retrospective single center study, including all consecutive FEVARs performed between September 2018 and December 2022 for the treatment of cAAAs and TAAAs with implantation of at least one BeGraft peripheral as the main BSG in one of the target vessels (TVs). Primary endpoints were technical success and TV instability of TV bridged with a BeGraft stent, as well as 30-day mortality and re-intervention rates. Secondary endpoints were follow-up TV instability, re-interventions, and mortality. RESULTS: A total of 113 patients (93 male, mean age 71.1±9.7) and 440 TV (14 scallops and 426 fenestrations) were included. Of the 440 TV, 406 received primary stenting. Be Grafts were used in 88.9% of these (n=361; celiac trunk [CT]=67, superior mesenteric artery [SMA]=98, right renal artery [RRA]=97, and left renal artery [LRA]=99). The technical success rate was 99.4% (359/361). The 30-day TV instability rate was 0.27% (1/361) with one early renal artery occlusion. During a median follow-up of 20 months (6-32), TV instability rate was 0.8% (3/361). Freedom from TV instability was 99.3%, 98.8%, and 98.8% at 1, 2, and 3 years, respectively. CONCLUSION: Early-term and mid-term results regarding TV instability are satisfactory and support the use of BeGraft as BSG in FEVAR for cAAAs and TAAAs. CLINICAL IMPACT: The findings of the current study show that the use of the BeGraft stent graft as bridging stent in FEVAR is associated with a high technical success and low early and mid-term instability rate and support the standard use as a bridging stent in fenestrated aneurysm repair.

The Impact of Target Vessel Anatomy and Bridging Stent Geometry on Branched Endovascular Aortic Repair Outcomes.

OBJECTIVE: This study aimed to evaluate the impact of target vessel anatomy and bridging stent geometry on target vessel instability in branched endovascular aortic repair (B-EVAR). METHODS: This retrospective, single centre cohort study included all consecutive B-EVARs performed between September 2018 and December 2022 for thoraco-abdominal aortic aneurysm (TAAA) or complex abdominal aortic aneurysm (CAAA). The primary endpoints were target vessel instability and related re-interventions at 12 months. Secondary endpoints were 30 day results, including target vessel instability and re-interventions. Target vessel instability analysis consisted of assessment of target vessel anatomy, including diameter, aortic trunk to branch angle, and tortuosity. Post-operative parameters included change of clock position/horizontal misalignment, bridging length (gap), sealing length, tortuosity, post-stenting angle, and oversizing ratio. RESULTS: A total of 69 patients (TAAA: n = 56, 81%; CAAA: n = 13, 19%) and 271 (133 visceral and 138 renal) target vessels were included. The cumulative incidence of target vessel instability was 4.8%, 6.4%, and 7.9% at one, two, and three years, respectively. In the renal target vessel group, vessel diameter ≤ 4 mm (hazard ratio [HR] 1.28, 95% confidence interval [CI] 1.116 - 2.54; p = .022) and a bridging length ≥ 25 mm (HR 1.320, 95% CI 1.066 - 1.636; p = .011) were associated with increased target vessel instability. In visceral vessels, a change in clock position/horizontal misalignment ≥ 70 minutes (HR 1.072, 95% CI 1.026 - 1.121; p = .002) showed a significant association with target vessel instability. CONCLUSION: Target vessel diameter, bridging length (gap), and horizontal misalignment seemed to be associated with adverse target vessel outcomes. This may be solved with more customised endograft solutions to reduce the negative impact of the latter parameter.

Sex Related Anatomical Differences in Patients With Aortic Arch Pathology and Their Impact on the Feasibility of Double and Triple Branched Endografts.

OBJECTIVE: To evaluate sex based differences in ascending aorta and arch anatomy in patients with underlying proximal aortic disease and to evaluate their impact on feasibility for total endovascular repair with custom made, arch branched devices. METHODS: This was a retrospective cross-sectional review of all patients undergoing open and or total endovascular arch repair due to distal ascending aorta and or aortic arch pathologies in a single high volume aortic centre between 2012 and 2022. Anatomical ascending aorta and aortic arch parameters were analysed on a centreline of flow on a dedicated 3D workstation. Sex related differences of the ascending aorta, aortic arch, and supra-aortic vessels were evaluated. Subsequently, four endovascular devices were assessed for feasibility: double and triple branched devices both for the Zenith (Cook Medical) and Relay (Terumo Aortic) platforms, first in accordance with the instructions for use and then considering the possibility of adjunctive cervical debranching. The primary endpoints were sex specific differences in aortic anatomy, while secondary endpoints included sex based feasibility of branched endograft devices. RESULTS: During the study period, 395 patients underwent total aortic arch repair, of whom 152 (51 female, 33.5%) had high quality available computed tomography angiographies and were included in the study. Female patients had a shorter proximal landing zone than male patients (22 mm vs. 47 mm; p < .001). Left subclavian artery dissection was more frequent in men (24.8% vs. 3.9%; p < .001). Other anatomical parameters showed a similar distribution between sexes. Female patients presented a lower feasibility for double branched devices (35.3% vs. 58.4%; p = .015) as well as a tendency for lower feasibility rates for triple branched devices (31.4% vs. 47.5%; p = .081). CONCLUSION: Although most ascending aortic and arch parameters showed similar trends in both sexes, the availability of a suitable proximal landing zone was lower in female patients. Consequently, female patients had lower feasibility rates for double arch branched endografts and, to lesser extent, for triple arch branched endografts.

Molecular Mechanisms Underlying Single Nucleotide Polymorphism-Induced Reactivity Decrease in CYP2D6.

Cytochrome P450 2D6 (CYP2D6) is one of the most important enzymes involved in drug metabolism. Genetic polymorphism can influence drug metabolism by CYP2D6 such that a therapy is seriously affected by under- or overdosing of drugs. However, a general explanation at the atomistic level for poor activity is missing so far. Here we show for the 20 most common single nucleotide polymorphisms (SNPs) of CYP2D6 that poor metabolism is driven by four mechanisms. We found in extensive all-atom molecular dynamics simulations that the rigidity of the I-helix (central helix), distance between central phenylalanines (stabilizing bound substrate), availability of basic residues on the surface of CYP2D6 (binding of cytochrome P450 reductase), and position of arginine 132 (electron transfer to heme) are essential for an extensive function of the enzyme. These results were applied to SNPs with unknown effects, and potential SNPs that may lead to poor drug metabolism were identified. The revealed molecular mechanisms might be important for other drug-metabolizing cytochrome P450 enzymes.

Indication and Outcome of Late Open Conversion after Abdominal Endovascular Aortic Repair.

BACKGROUND: Endovascular aortic repair (EVAR) has become the standard of care for patients with infrarenal aortic aneurysms over the last 2 decades. Endograft technology and treatment of complications like endoleaks, graft migration, or graft occlusion developed over time. However, sometimes open surgical conversion maybe required. Our aim was to analyze the indications, the technical aspects and outcomes in patients who underwent open conversion after EVAR with different types and generations of endografts. METHODS: This retrospective single-center study reviewed all patients who underwent EVAR from 2004 to 2020. Open surgical conversions >1 month post EVAR were identified. Conversions for graft infection were excluded. Indications for conversion and operative technique were analyzed. Primary endpoint of the study was 30-day mortality. Secondary endpoints were re-interventions and follow-up mortality. RESULTS: During 2004 and 2020, 443 consecutive EVARs were performed, and 28 patients required open surgical conversion, with an additional 3 referred from other hospitals (N = 31). The median age was 75 (range 58-93); 94% were male. Conversion was performed after a median time of 55 months (range 16-209). Twenty patients underwent elective and 11 emergency conversion. Indications for open conversion were graft migration, respectively, disease progression with endoleak type Ia and/or Ib in 52% (16/31) and sac expansion due to endoleak type II in 26% (8/31). Of the 31 patients, 17 (55%) had at least one previous endovascular re-intervention. All patients met the device-specific instructions for use for each implanted endograft. In-hospital intervention rate was 16% (5/31). Thirty-day mortality rate was 3% (1/31) with one patient died due to multiorgan failure after rupture with complete endograft replacement. Five patients (16%) died during follow-up. Mid-term follow-up was 47.5 months (range 24-203) with estimated cumulative survival rates of 97%, 89%, and 84%, at 1, 3, and 5 years, respectively. CONCLUSIONS: Late open conversion remains a valuable treatment option and can be performed safely in elective and emergency setting with a low early mortality. Lifelong surveillance and prompt intervention when necessary are essential in ensuring optimal outcomes after EVAR and preventing the need for emergent conversions.

Diversification of mammalian deltaviruses by host shifting.

Hepatitis delta virus (HDV) is an unusual RNA agent that replicates using host machinery but exploits hepatitis B virus (HBV) to mobilize its spread within and between hosts. In doing so, HDV enhances the virulence of HBV. How this seemingly improbable hyperparasitic lifestyle emerged is unknown, but it underpins the likelihood that HDV and related deltaviruses may alter other host-virus interactions. Here, we show that deltaviruses diversify by transmitting between mammalian species. Among 96,695 RNA sequence datasets, deltaviruses infected bats, rodents, and an artiodactyl from the Americas but were absent from geographically overrepresented Old World representatives of each mammalian order, suggesting a relatively recent diversification within the Americas. Consistent with diversification by host shifting, both bat and rodent-infecting deltaviruses were paraphyletic, and coevolutionary modeling rejected cospeciation with mammalian hosts. In addition, a 2-y field study showed common vampire bats in Peru were infected by two divergent deltaviruses, indicating multiple introductions to a single host species. One vampire bat-associated deltavirus was detected in the saliva of up to 35% of individuals, formed phylogeographically compartmentalized clades, and infected a sympatric bat, illustrating horizontal transmission within and between species on ecological timescales. Consistent absence of HBV-like viruses in two deltavirus-infected bat species indicated acquisitions of novel viral associations during the divergence of bat and human-infecting deltaviruses. Our analyses support an American zoonotic origin of HDV and reveal prospects for future cross-species emergence of deltaviruses. Given their peculiar life history, deltavirus host shifts will have different constraints and disease outcomes compared to ordinary animal pathogens.

Cyclobutanone Inhibitors of Diaminopimelate Desuccinylase (DapE) as Potential New Antibiotics.

Based on our previous success in using cyclobutanone derivatives as enzyme inhibitors, we have designed and prepared a 37-member library of α-aminocyclobutanone amides and sulfonamides, screened for inhibition of the bacterial enzyme diaminopimelate desuccinylase (DapE), which is a promising antibiotic target, and identified several inhibitors with micromolar inhibitory potency. Molecular docking suggests binding of the deprotonated hydrate of the strained cyclobutanone, and thermal shift analysis with the most potent inhibitor (3y, IC50 = 23.1 µM) enabled determination of a Ki value of 10.2 +/- 0.26 µM and observed two separate Tm values for H. influenzae DapE (HiDapE).

Ecological conditions predict the intensity of Hendra virus excretion over space and time from bat reservoir hosts.

The ecological conditions experienced by wildlife reservoirs affect infection dynamics and thus the distribution of pathogen excreted into the environment. This spatial and temporal distribution of shed pathogen has been hypothesised to shape risks of zoonotic spillover. However, few systems have data on both long-term ecological conditions and pathogen excretion to advance mechanistic understanding and test environmental drivers of spillover risk. We here analyse three years of Hendra virus data from nine Australian flying fox roosts with covariates derived from long-term studies of bat ecology. We show that the magnitude of winter pulses of viral excretion, previously considered idiosyncratic, are most pronounced after recent food shortages and in bat populations displaced to novel habitats. We further show that cumulative pathogen excretion over time is shaped by bat ecology and positively predicts spillover frequency. Our work emphasises the role of reservoir host ecology in shaping pathogen excretion and provides a new approach to estimate spillover risk.

Functional traits explain waterbirds' host status, subtype richness, and community-level infection risk for avian influenza.

Species functional traits can influence pathogen transmission processes, and consequently affect species' host status, pathogen diversity, and community-level infection risk. We here investigated, for 143 European waterbird species, effects of functional traits on host status and pathogen diversity (subtype richness) for avian influenza virus at species level. We then explored the association between functional diversity and HPAI H5Nx occurrence at the community level for 2016/17 and 2021/22 epidemics in Europe. We found that both host status and subtype richness were shaped by several traits, such as diet guild and dispersal ability, and that the community-weighted means of these traits were also correlated with community-level risk of H5Nx occurrence. Moreover, functional divergence was negatively associated with H5Nx occurrence, indicating that functional diversity can reduce infection risk. Our findings highlight the value of integrating trait-based ecology into the framework of diversity-disease relationship, and provide new insights for HPAI prediction and prevention.

Single-cell analysis of localized prostate cancer patients links high Gleason score with an immunosuppressive profile.

BACKGROUND: Evading immune surveillance is a hallmark for the development of multiple cancer types. Whether immune evasion contributes to the pathogenesis of high-grade prostate cancer (HGPCa) remains an area of active inquiry. METHODS: Through single-cell RNA sequencing and multicolor flow cytometry of freshly isolated prostatectomy specimens and matched peripheral blood, we aimed to characterize the tumor immune microenvironment (TME) of localized prostate cancer (PCa), including HGPCa and low-grade prostate cancer (LGPCa). RESULTS: HGPCa are highly infiltrated by exhausted CD8+ T cells, myeloid cells, and regulatory T cells (TRegs). These HGPCa-infiltrating CD8+ T cells expressed high levels of exhaustion markers including TIM3, TOX, TCF7, PD-1, CTLA4, TIGIT, and CXCL13. By contrast, a high ratio of activated CD8+  effector T cells relative to TRegs and myeloid cells infiltrate the TME of LGPCa. HGPCa CD8+  tumor-infiltrating lymphocytes (TILs) expressed more androgen receptor and prostate-specific membran antigen yet less prostate-specific antigen than the LGPCa CD8+  TILs. The PCa TME was infiltrated by macrophages but these did not clearly cluster by M1 and M2 markers. CONCLUSIONS: Our study reveals a suppressive TME with high levels of CD8+ T cell exhaustion in localized PCa, a finding enriched in HGPCa relative to LGPCa. These studies suggest a possible link between the clinical-pathologic risk of PCa and the associated TME. Our results have implications for our understanding of the immunologic mechanisms of PCa pathogenesis and the implementation of immunotherapy for localized PCa.

Tetrazole-based inhibitors of the bacterial enzyme N-succinyl-l,l-2,6-diaminopimelic acid desuccinylase as potential antibiotics.

Based on a hit from a high-throughput screen, a series of phenyltetrazole amides was synthesized and assayed for inhibitory potency against DapE from Haemophilus influenzae (HiDapE). The inhibitory potency was modest but confirmed, with the most potent analog containing an aminothiazole moiety displaying an IC50 = 50.2 ± 5.0 µM. Docking reveals a potential binding mode wherein the amide carbonyl bridges both zinc atoms in the active site, and the tetrazole forms key hydrogen bonds with Arg330.

Synthesis and characterization of the N-succinyl-l,l-diaminopimelic acid desuccinylase (DapE) alternate substrate analog N,N-dimethyl-l,l-SDAP.

Growing antibiotic resistance by pathogenic bacteria has led to a global crisis. The bacterial enzyme N-succinyl-l,l-diaminopimelic acid desuccinylase (DapE) provides a very attractive target for the discovery of a new class of antibiotics, as it resides exclusively in many pathogenic bacterial strains and is a key enzyme in the lysine biosynthetic pathway. This pathway is responsible for the production of lysine as well as meso-diaminopimelate (m-DAP), both of which are required for peptidoglycan cell-wall synthesis, and lysine for peptide synthesis. The enzyme DapE catalyzes the hydrolysis of N-succinyl-l,l-diaminopimelic acid (l,l-SDAP) to succinate and l,l-diaminopimelic acid (l,l-DAP), and due to its absence in humans, inhibition of DapE avoids mechanism-based side effects. We have executed the asymmetric synthesis of N,N-dimethyl-SDAP, an l,l-SDAP substrate analog and an analog of the synthetic substrate of our previously described DapE assay. Previous modeling studies advocated that N,N-dimethyl-SDAP might function as an inhibitor, however the compound behaves as a substrate, and we have demonstrated the use of N,N-dimethyl-SDAP as the substrate in a modified ninhydrin-based DapE assay. Thermal shift experiments of DapE in the presence of N,N-dimethyl-SDAP are consistent with a melt temperature (Tm) shifted by succinate, the product of enzymatic hydrolysis.

In Silico Binding of 2-Aminocyclobutanones to SARS-CoV-2 Nsp13 Helicase and Demonstration of Antiviral Activity.

The landscape of viral strains and lineages of SARS-CoV-2 keeps changing and is currently dominated by Delta and Omicron variants. Members of the latest Omicron variants, including BA.1, are showing a high level of immune evasion, and Omicron has become a prominent variant circulating globally. In our search for versatile medicinal chemistry scaffolds, we prepared a library of substituted ɑ-aminocyclobutanones from an ɑ-aminocyclobutanone synthon (11). We performed an in silico screen of this actual chemical library as well as other virtual 2-aminocyclobutanone analogs against seven SARS-CoV-2 nonstructural proteins to identify potential drug leads against SARS-CoV-2, and more broadly against coronavirus antiviral targets. Several of these analogs were initially identified as in silico hits against SARS-CoV-2 nonstructural protein 13 (Nsp13) helicase through molecular docking and dynamics simulations. Antiviral activity of the original hits as well as ɑ-aminocyclobutanone analogs that were predicted to bind more tightly to SARS-CoV-2 Nsp13 helicase are reported. We now report cyclobutanone derivatives that exhibit anti-SARS-CoV-2 activity. Furthermore, the Nsp13 helicase enzyme has been the target of relatively few target-based drug discovery efforts, in part due to a very late release of a high-resolution structure accompanied by a limited understanding of its protein biochemistry. In general, antiviral agents initially efficacious against wild-type SARS-CoV-2 strains have lower activities against variants due to heavy viral loads and greater turnover rates, but the inhibitors we are reporting have higher activities against the later variants than the wild-type (10-20X). We speculate this could be due to Nsp13 helicase being a critical bottleneck in faster replication rates of the new variants, so targeting this enzyme affects these variants to an even greater extent. This work calls attention to cyclobutanones as a useful medicinal chemistry scaffold, and the need for additional focus on the discovery of Nsp13 helicase inhibitors to combat the aggressive and immune-evading variants of concern (VOCs).

Carborane-Containing Hydroxamate MMP Ligands for the Treatment of Tumors Using Boron Neutron Capture Therapy (BNCT): Efficacy without Tumor Cell Entry.

New carborane-bearing hydroxamate matrix metalloproteinase (MMP) ligands have been synthesized for boron neutron capture therapy (BNCT) with nanomolar potency against MMP-2, -9 and -13. New analogs are based on MMP inhibitor CGS-23023A, and two previously reported MMP ligands 1 (B1) and 2 (B2) were studied in vitro for BNCT activity. The boronated MMP ligands 1 and 2 showed high in vitro tumoricidal effects in an in vitro BNCT assay, exhibiting IC50 values for 1 and 2 of 2.04 × 10-2 mg/mL and 2.67 × 10-2 mg/mL, respectively. The relative killing effect of 1 to L-boronophenylalanine (BPA) is 0.82/0.27 = 3.0, and that of 2 is 0.82/0.32 = 2.6, whereas the relative killing effect of 4 is comparable to boronophenylalanine (BPA). The survival fraction of 1 and 2 in a pre-incubation boron concentration at 0.143 ppm 10B and 0.101 ppm 10B, respectively, were similar, and these results suggest that 1 and 2 are actively accumulated through attachment to the Squamous cell carcinoma (SCC)VII cells. Compounds 1 and 2 very effectively killed glioma U87 delta EGFR cells after BNCT. This study is noteworthy in demonstrating BNCT efficacy through binding to MMP enzymes overexpressed at the surface of the tumor cell without tumor cell penetration.

Iron dysregulation in COVID-19 and reciprocal evolution of SARS-CoV-2: Natura nihil frustra facit.

After more than a year of the COVID-19 pandemic, SARS-CoV-2 infection rates with newer variants continue to devastate much of the world. Global healthcare systems are overwhelmed with high positive patient numbers. Silent hypoxia accompanied by rapid deterioration and some cases with septic shock is responsible for COVID-19 mortality in many hospitalized patients. There is an urgent need to further understand the relationships and interplay with human host components during pathogenesis and immune evasion strategies. Currently, acquired immunity through vaccination or prior infection usually provides sufficient protection against the emerging variants of SARS-CoV-2 except Omicron variant requiring recent booster. New strains have shown higher viral loads and greater transmissibility with more severe disease presentations. Notably, COVID-19 has a peculiar prognosis in severe patients with iron dysregulation and hypoxia which is still poorly understood. Studies have shown abnormally low serum iron levels in severe infection but a high iron overload in lung fibrotic tissue. Data from our in-silico structural analysis of the spike protein sequence along with host proteolysis processing suggests that the viral spike protein fragment mimics Hepcidin and is resistant to the major human proteases. This functional spike-derived peptide dubbed "Covidin" thus may be intricately involved with host ferroportin binding and internalization leading to dysregulated host iron metabolism. Here, we propose the possible role of this potentially allogenic mimetic hormone corresponding to severe COVID-19 immunopathology and illustrate that this molecular mimicry is responsible for a major pathway associated with severe disease status. Furthermore, through 3D molecular modeling and docking followed by MD simulation validation, we have unraveled the likely role of Covidin in iron dysregulation in COVID-19 patients. Our meta-analysis suggests the Hepcidin mimetic mechanism is highly conserved among its host range as well as among all new variants to date including Omicron. Extensive analysis of current mutations revealed that new variants are becoming alarmingly more resistant to selective human proteases associated with host defense.