The receptor-binding domain (RBD) of the severe acute respiratory syndrome coronavirus 2s pike (S) protein playsacentral role in mediating the first step of virus infection to cause disease:v irus binding to angiotensin-converting enzyme 2( ACE2) receptors on human host cells.T herefore, S/RBD is an ideal target for blocking and neutralization therapies to prevent and treat coronavirus disease 2019 (COVID-19). Using at arget-based selection approach, we developed oligonucleotide aptamers containing ac onserved sequence motif that specifically targets S/RBD.S ynthetic aptamers had high binding affinity for S/RBD-coated virus mimics (K D % 7nM) and also blocked interaction of S/RBD with ACE2 receptors (IC 50 % 5nM). Importantly,a ptamers were able to neutralizeSprotein-expressing viral particles and prevent host cell infection, suggesting apromising COVID-19 therapys trategy.

The association of the receptor binding domain (RBD) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein with human angiotensin-converting enzyme 2 (hACE2) represents the first required step for cellular entry. SARS-CoV-2 has continued to evolve with the emergence of several novel variants, and amino acid changes in the RBD have been implicated with increased fitness and potential for immune evasion. Reliably predicting the effect of amino acid changes on the ability of the RBD to interact more strongly with the hACE2 can help assess the implications for public health and the potential for spillover and adaptation into other animals. Here, we introduce a two-step framework that first relies on 48 independent 4-ns molecular dynamics (MD) trajectories of RBD−hACE2 variants to collect binding energy terms decomposed into Coulombic, covalent, van der Waals, lipophilic, generalized Born solvation, hydrogen bonding, π−π packing, and self-contact correction terms. The second step implements a neural network to classify and quantitatively predict binding affinity changes using the decomposed energy terms as descriptors. The computational base achieves a validation accuracy of 82.8% for classifying single–amino acid substitution variants of the RBD as worsening or improving binding affinity for hACE2 and a correlation coefficient of 0.73 between predicted and experimentally calculated changes in binding affinities. Both metrics are calculated using a fivefold cross-validation test. Our method thus sets up a framework for screening binding affinity changes caused by unknown single– and multiple–amino acid changes offering a valuable tool to predict host adaptation of SARS-CoV-2 variants toward tighter hACE2 binding.

The receptor-binding domain (RBD) of the severe acute respiratory syndrome coronavirus 2s pike (S) protein playsacentral role in mediating the first step of virus infection to cause disease:v irus binding to angiotensin-converting enzyme 2( ACE2) receptors on human host cells.T herefore, S/RBD is an ideal target for blocking and neutralization therapies to prevent and treat coronavirus disease 2019 (COVID-19). Using at arget-based selection approach, we developed oligonucleotide aptamers containing ac onserved sequence motif that specifically targets S/RBD.S ynthetic aptamers had high binding affinity for S/RBD-coated virus mimics (K D % 7nM) and also blocked interaction of S/RBD with ACE2 receptors (IC 50 % 5nM). Importantly,a ptamers were able to neutralizeSprotein-expressing viral particles and prevent host cell infection, suggesting apromising COVID-19 therapys trategy.

SARS-CoV-2 antigens that are displayed on liposomes and lyophilized are thermostable and protect mice from lethal virus challenge.

Despite progress describing the effects of persistent organic pollutants (POPs) on the central nervous system, the effect of POPs on enteric nervous system (ENS) function remains underexplored. We studied the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a POP and a potent aryl hydrocarbon receptor (AHR) ligand, on the ENS and intestinal motility in mice. C57Bl/6J mice treated with TCDD (2.4 µg/kg body weight) for eight weeks (once per week) exhibited significant delay in intestinal motility as shown by reduced stool frequency, prolonged intestinal transit time, and a persistence of the dye in the jejunum compared to control mice with maximal dye retention in the ileum. TCDD significantly increased Cyp1a1 expression, an AHR target gene and reduced the total number of neurons and affected nitrergic neurons in cells isolated from WT mice, but not Ahr-/- mice. In immortalized fetal enteric neuronal (IM-FEN) cells TCDD induced nuclear translocation of AHR as well as increased Cyp1a1 expression. AHR activation did not affect neuronal proliferation. However, AHR activation resulted in enteric neuronal toxicity, specifically, nitrergic neurons. Our results demonstrate that TCDD adversely affects nitrergic neurons and thereby contributes to delayed intestinal motility. These findings suggest that AHR signaling in the ENS may play a role in modulating TCDD induced gastrointestinal pathophysiology.