This research focuses on analyzing the dynamics of neutralizing antibody (nAbs) titers against type 5 adenovirus (Ad5) in the adult population of Russia following vaccination against the novel ...coronavirus infection with recombinant adenovirus type-5 COVID-19 vaccine (CanSino Biologics, China). The impact of the Ad5 vector on nAb titers was investigated using 302 blood serum samples from individuals who received a single dose of the Ad5-nCoV vector vaccine. The research revealed that 33.8% of adults in Russia had pre-existing anti-Ad5 nAbs before the pandemic. Notably, 40% of vaccinated individuals did not exhibit an increase in nAbs titers upon receiving the Ad5-based vaccine. However, in the group with no or low titers of anti-Ad5 nAbs (1:10–1:40), a significant 8-16-fold increase in nAb titers to Ad5 was observed.
•The research revealed that 33.8% of adults in Russia had pre-existing anti-Ad5 nAbs before the pandemic.•40% of vaccinated individuals did not exhibit an increase in nAbs titers upon receiving the Ad5-based vaccine.•A significant 8-16-fold increase in nAb titers to Ad5 was observed in the group with no or low titers of anti-Ad5 nAbs.
The pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection involves dysregulations of iron metabolism, and although the mechanism of this pathology is not yet fully ...understood, correction of iron metabolism pathways seems a promising pharmacological target. The previously observed effect of inhibiting SARS-CoV-2 infection by ferristatin II, an inducer of transferrin receptor 1 (TfR1) degradation, prompted the study of competition between Spike protein and TfR1 ligands, especially lactoferrin (Lf) and transferrin (Tf). We hypothesized molecular mimicry of Spike protein as cross-reactivity of Spike-specific antibodies with Tf and Lf. Thus, strong positive correlations (R
2
> 0.95) were found between the level of Spike-specific IgG antibodies present in serum samples of COVID-19-recovered and Sputnik V-vaccinated individuals and their Tf-binding activity assayed with peroxidase-labeled anti-Tf. In addition, we observed cross-reactivity of Lf-specific murine monoclonal antibody (mAb) towards the SARS-CoV-2 Spike protein. On the other hand, the interaction of mAbs produced to the receptor-binding domain (RBD) of the Spike protein with recombinant RBD protein was disrupted by Tf, Lf, soluble TfR1, anti-TfR1 aptamer, as well as by peptides RGD and GHAIYPRH. Furthermore, direct interaction of RBD protein with Lf, but not Tf, was observed, with affinity of binding estimated by K
D
to be 23 nM and 16 nM for apo-Lf and holo-Lf, respectively. Treatment of Vero E6 cells with apo-Lf and holo-Lf (1–4 mg/mL) significantly inhibited SARS-CoV-2 replication of both Wuhan and Delta lineages. Protective effects of Lf on different arms of SARS-CoV-2-induced pathogenesis and possible consequences of cross-reactivity of Spike-specific antibodies are discussed.
The influenza NS1 protein is involved in suppression of the host immune response. Recently, there is growing evidence that prion-like protein aggregation plays an important role in cellular signaling ...and immune responses. In this work, we obtained a recombinant, influenza A NS1 protein and showed that it is able to form amyloid-like fibrils in vitro. Using proteolysis and subsequent mass spectrometry, we showed that regions resistant to protease hydrolysis highly differ between the native NS1 form (NS1-N) and fibrillar form (NS1-F); this indicates that significant structural changes occur during fibril formation. We also found a protein fragment that is capable of inducing the process of fibrillogenesis at 37 °C. The discovery of the ability of NS1 to form amyloid-like fibrils may be relevant to uncovering relationships between influenza A infection and modulation of the immune response.
•Recombinant NS1 protein is capable of forming amyloid-like fibrils.•Native form NS1 features a protease-resistant fragment from a.a. residues 1 to 78.•The fibrillar NS1 form's C-terminus is hydrolyzed by trypsin least of all.•During fibril formation, SDS-resistant non-native dimers form.•The NS1 Beta domain likely plays an important role in conformational transition.
Two influenza A nucleoprotein variants (wild-type: G102R; and mutant: G102R and E292G) were studied with regard to macro-molecular interactions in oligomeric form (24-mers). The E292G mutation has ...been previously shown to provide cold adaptation. Molecular dynamics simulations of these complexes and trajectory analysis showed that the most significant difference between the obtained models was distance between nucleoprotein complex strands. The isolated complexes of two ribonucleoprotein variants were characterized by transmission electron microscopy and differential scanning fluorimetry (DSF). Presence of the E292G substitution was shown by DSF to affect nucleoprotein complex melting temperature. In the filament interface peptide model, it was shown that the peptide corresponding in primary structure to the wild-type NP (SGYDF
E
REGYS) is prone to temperature-dependent self-association, unlike the peptide corresponding to E292G substitution (SGYDF
G
REGYS). It was also shown that the SGYDF
E
REGYS peptide is capable of interacting with a monomeric nucleoprotein (wild type); this interaction's equilibrium dissociation constant is five orders of magnitude lower than for the SGYDF
G
REGYS peptide. Using small-angle neutron scattering (SANS), the supramolecular structures of isolated complexes of these proteins were studied at temperatures of 15, 32, and 37 °C. SANS data show that the structures of the studied complexes at elevated temperature differ from the rod-like particle model and react differently to temperature changes. The data suggest that the mechanism behind cold adaptation with E292G is associated with a weakening of the interaction between strands of the ribonucleoprotein complex and, as a result, the appearance of inter-chain interface flexibility necessary for complex function at low temperature.
Communicated by Ramaswamy H. Sarma
This manuscript describes the chemical synthesis of a compound similar to fluorene and Congo red, including characterization of its spectral properties. It was shown that the dye, during interaction ...with amyloid-like fibrils of several proteins (lysozyme, insulin, and beta-2-microglobulin), has the ability to change fluorescent spectrum. In contrast, monomeric forms of these proteins did not induce significant spectral changes.
•The AF dye changes its spectral characteristics when bound to amyloid-like fibrils.•The amyloid detecting properties were verified using three amyloidogenic proteins.•Slight changes in AF dye spectra were observed when binding to insulin hexamers.
Determination of the mechanism of action of potential medicinal substances is an integral stage in development of novel drugs. The interaction of antiviral peptide PB1
6–14
with lipid membranes in ...cell and cell-free model systems is demonstrated. Penetration of a fluorescently tagged analog of peptide into cells has been observed for 15 min using continuous-flow cytofluorometry and confocal microscopy. The specific features of interaction of the peptide under study with cell membranes have been studied using small-angle neutron scattering (SANS), atomic force microscopy (AFM), and dynamic light scattering. It is shown that model liposomes (PC/PG) increased in size in the presence of peptide (in a 5% ethanol/5% DMSO/PBS buffer), while the ζ potential changed only slightly, which can be interpreted as a consequence of a change in the surface charge and may indicate peptide ability to interact with a lipid bilayer (not excluding its penetration into the membrane). The data obtained can be used both for studying the mechanism of therapeutic peptide transport and for developing drug-delivery agents.
The review describes the application of small-angle scattering (SAS) of neutrons and complementary methods to study the structures of biomacromolecules. Here we cover SAS techniques, such as the ...contrast variation, the neutron spin-echo, and the solution of direct and inverse problems of three-dimensional reconstruction of the structures of macromolecules from SAS spectra by means of molecular modeling. A special section is devoted to specific objects of research, such as supramolecular complexes, influenza virus nucleoprotein, and chromatin.
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