Smallpox constitutes a major bioterrorism threat, which underscores the need to develop antiviral drugs for rapid response in the event of an attack. Viral processivity factors are attractive drug ...targets in being both specific and essential for their cognate DNA polymerases to synthesize extended strands of DNA. An in silico model of the vacinnia virus processivity factor, comprised of the A20 and D4 heterocomplex, was constructed and used for lead optimization of an indole-based scaffold identified earlier from a high-throughput screening. On the basis of this model, a new class of potent antivirals against vaccinia virus was designed and synthesized, of which two (24a and 24b) exhibited superior improvement over the parent scaffold (IC50 = 42 and 46 vs 82000 nM, respectively). The ability of 24a to suppress vaccinia DNA synthesis is supported by the inhibition of late viral gene expression, as well as by the diminished incorporation of bromodeoxyuridine into viral replication factories.
Many SARS-CoV-2 variants have emerged during the course of the COVID-19 pandemic. These variants have acquired mutations conferring phenotypes such as increased transmissibility or virulence, or ...causing diagnostic, therapeutic, or immune escape. Detection of Alpha and the majority of Omicron sublineages by PCR relied on the so-called S gene target failure due to the deletion of six nucleotides coding for amino acids 69-70 in the spike (S) protein. Detection of hallmark mutations in other variants present in samples relied on whole genome sequencing. However, whole genome sequencing as a diagnostic tool is still in its infancy due to geographic inequities in sequencing capabilities, higher cost compared to other molecular assays, longer turnaround time from sample to result, and technical challenges associated with producing complete genome sequences from samples that have low viral load and/or high background. Hence, there is a need for rapid genotyping assays. In order to rapidly generate information on the presence of a variant in a given sample, we have created a panel of four triplex RT-qPCR assays targeting 12 mutations to detect and differentiate all five variants of concern: Alpha, Beta, Gamma, Delta, and Omicron. We also developed an expanded pentaplex assay that can reliably distinguish among the major sublineages (BA.1-BA.5) of Omicron.
, analytical and clinical testing of the variant panel indicate that the assays exhibit high sensitivity and specificity. This panel can help fulfill the need for rapid identification of variants in samples, leading to quick decision making with respect to public health measures, as well as treatment options for individuals. Compared to sequencing, these genotyping PCR assays allow much faster turn-around time from sample to results-just a couple hours instead of days or weeks.
Wambi, C., Sanzari, J., Wan, X. S., Nuth, M., Davis, J., Ko, Y. H., Sayers, C. M., Baran, M., Ware, J. H. and Kennedy, A. R. Dietary Antioxidants Protect Hematopoietic Cells and Improve Animal ...Survival after Total-Body Irradiation. Radiat. Res. 169, 384–396 (2008). The purpose of this study was to determine whether a dietary supplement consisting of l-selenomethionine, vitamin C, vitamin E succinate, α-lipoic acid and N-acetyl cysteine could improve the survival of mice after total-body irradiation. Antioxidants significantly increased the 30-day survival of mice after exposure to a potentially lethal dose of X rays when given prior to or after animal irradiation. Pretreatment of animals with antioxidants resulted in significantly higher total white blood cell and neutrophil counts in peripheral blood at 4 and 24 h after 1 Gy and 8 Gy. Antioxidants were effective in preventing peripheral lymphopenia only after low-dose irradiation. Antioxidant supplementation was also associated with increased bone marrow cell counts after irradiation. Supplementation with antioxidants was associated with increased Bcl2 and decreased Bax, caspase 9 and TGF-β1 mRNA expression in the bone marrow after irradiation. Maintenance of the antioxidant diet was associated with improved recovery of the bone marrow after sublethal or potentially lethal irradiation. Taken together, oral supplementation with antioxidants appears to be an effective approach for radioprotection of hematopoietic cells and improvement of animal survival, and modulation of apoptosis is implicated as a mechanism for the radioprotection of the hematopoietic system by antioxidants.
Dietary antioxidants have radioprotective effects after γ-radiation exposure that limit hematopoietic cell depletion and improve animal survival. The purpose of this study was to determine whether a ...dietary supplement consisting of l-selenomethionine, vitamin C, vitamin E succinate, α-lipoic acid and N-acetyl cysteine could improve survival of mice after proton total-body irradiation (TBI). Antioxidants significantly increased 30-day survival of mice only when given after irradiation at a dose less than the calculated LD50/30; for these data, the dose-modifying factor (DMF) was 1.6. Pretreatment of animals with antioxidants resulted in significantly higher serum total white blood cell, polymorphonuclear cell and lymphocyte cell counts at 4 h after 1 Gy but not 7.2 Gy proton TBI. Antioxidants significantly modulated plasma levels of the hematopoietic cytokines Flt-3L and TGFβ1 and increased bone marrow cell counts and spleen mass after TBI. Maintenance of the antioxidant diet resulted in improved recovery of peripheral leukocytes and platelets after sublethal and potentially lethal TBI. Taken together, oral supplementation with antioxidants appears to be an effective approach for radioprotection of hematopoietic cells and improvement of animal survival after proton TBI.
Vaccinia virus (VACV) is a poxvirus, and the VACV D4 protein serves both as a uracil-DNA glycosylase and as an essential component required for processive DNA synthesis. The VACV A20 protein has no ...known catalytic function itself but associates with D4 to form the D4-A20 heterodimer that functions as the poxvirus DNA processivity factor. The heterodimer enables the DNA polymerase to efficiently synthesize extended strands of DNA. Upon characterizing the interaction between D4 and A20, we observed that the C terminus of D4 is susceptible to perturbation. Further analysis demonstrated that a conserved hexapeptide stretch at the extreme C terminus of D4 is essential for maintaining protein integrity, as assessed by its requirement for the production of soluble recombinant protein that is functional in processive DNA synthesis. From the known crystal structures of D4, the C-terminal hexapeptide is shown to make intramolecular contact with residues spanning the inner core of the protein. Our mutational analysis revealed that a tripeptide motif (215GFI217) within the hexapeptide comprises apparent residues necessary for the contact. Prediction of protein disorder identified the hexapeptide and several regions upstream of Gly215 that comprise residues of the interface surfaces of the D4-A20 heterodimer. Our study suggests that 215GFI217 anchors these potentially dynamic upstream regions of the protein to maintain protein integrity. Unlike uracil-DNA glycosylases from diverse sources, where the C termini are disordered and do not form comparable intramolecular contacts, this feature may be unique to orthopoxviruses.
To advance a novel concept of debulking virus in the oral cavity, the primary site of viral replication, virus-trapping proteins CTB-ACE2 were expressed in chloroplasts and clinical-grade plant ...material was developed to meet FDA requirements. Chewing gum (2 g) containing plant cells expressed CTB-ACE2 up to 17.2 mg ACE2/g dry weight (11.7% leaf protein), have physical characteristics and taste/flavor like conventional gums, and no protein was lost during gum compression. CTB-ACE2 gum efficiently (>95%) inhibited entry of lentivirus spike or VSV-spike pseudovirus into Vero/CHO cells when quantified by luciferase or red fluorescence. Incubation of CTB-ACE2 microparticles reduced SARS-CoV-2 virus count in COVID-19 swab/saliva samples by >95% when evaluated by microbubbles (femtomolar concentration) or qPCR, demonstrating both virus trapping and blocking of cellular entry. COVID-19 saliva samples showed low or undetectable ACE2 activity when compared with healthy individuals (2,582 versus 50,126 ΔRFU; 27 versus 225 enzyme units), confirming greater susceptibility of infected patients for viral entry. CTB-ACE2 activity was completely inhibited by pre-incubation with SARS-CoV-2 receptor-binding domain, offering an explanation for reduced saliva ACE2 activity among COVID-19 patients. Chewing gum with virus-trapping proteins offers a general affordable strategy to protect patients from most oral virus re-infections through debulking or minimizing transmission to others.
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With a large majority of the global population unvaccinated and outbreaks of variants with higher viral load, new methods are needed to decrease SARS-CoV-2 transmission and infection. Daniell et al. report that chewing gum containing plant cells expressing angiotensin-converting enzyme 2 efficiently traps SARS-CoV-2 in COVID-19 patient saliva or swab samples.
We recently developed compound FC-7269 for targeting the Molluscum contagiosum virus processivity factor (mD4) and demonstrated its ability to inhibit viral processive DNA synthesis in vitro and ...cellular infection of an mD4-dependent virus (Antiviral Res 211, 2023,105520). However, despite a thorough medicinal chemistry campaign we were unable to generate a potent second analog as a requisite for drug development. We overcame this impasse, by conjugating a short hydrophobic trivaline peptide to FC-7269 to produce FC-TriVal-7269 which significantly increased antiviral potency and reduced cellular toxicity.
•The small molecule 7269 is the first antiviral specific for Molluscum contagiosum.•Exhaustive med chem failed to generate a second compound for drug development.•The impasse was solved by conjugating a Tri-Valine peptide to 7269.•The TriVal-7269 molecule has greater antiviral potency and is not toxic to cells.•Peptide-conjugated drugs represent a new approach to antiviral drug development.
Molluscum contagiosum (MC) is an infectious disease that occurs only in humans with a tropism that is narrowly restricted to the outermost epidermal layer of the skin. Molluscum contagiosum virus ...(MCV) is the causative agent of MC which produces skin lesions that can persist for months to several years. MCV is efficiently transmitted by direct physical contact or by indirect contact with fomites. MC is most prevalent in children and immune compromised patients. The failure to develop a drug that targets MCV replication has been hampered for decades by the inability to propagate MCV in cell culture. To address this dilemma, we recently engineered a surrogate poxvirus expressing the MCV processivity factor (mD4) as the drug target. The mD4 protein is essential for viral replication by keeping the viral polymerase tethered to the DNA template. In this study we have designed and synthesized a lead compound (7269) that is able to prevent mD4 dependent processive DNA synthesis in vitro (IC50 = 6.8 μM) and effectively inhibit propagation of the mD4-VV surrogate virus in BSC-1 cells (EC50 = 13.2 μM) with negligible cytotoxicity. In human liver microsomes, 7269 was shown to be stable for almost 2 h. When tested for penetration into human cadaver skin in a formulated gel, the level of 7269 in the epidermal layer was nearly 100 times the concentration (EC50) needed to inhibit propagation of the mD4-VV surrogate virus in BSC-1 cells. The gel formulated 7269 was scored as a non-irritant on skin and shown to have a shelf-life that was completely stable after several months. In summary, 7269 is a potential Lead for becoming the first MCV anti-viral compound to treat MC and thereby, addresses this unmet medical need that has persisted for many decades.
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•Developing antivirals to treat Molluscum contagiosum virus skin disease.•Hybrid virus for antiviral testing since Molluscum cannot grow in culture.•Topical gel for testing delivery of antiviral into human cadaver skin.•Test antivirals for specificity, cytotoxicity, skin irritation, shelf-life.
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