scholarly journals DECREASED BREADTH OF THE ANTIBODY RESPONSE TO THE SPIKE PROTEIN OF SARS-CoV-2 AFTER VACCINATION

2021 ◽  
Author(s):  
Lydia Horndler ◽  
Pilar Delgado ◽  
Salvador Romero-Pinedo ◽  
Marina Quesada ◽  
Ivaylo Balabanov ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Protein Sequence ◽  
Rapid Development ◽  
Humoral Response ◽  
Spike Protein ◽  
Relative Reduction ◽  
Original Strain ◽  
S Protein ◽  
Highly Sensitive ◽  
Igg1 Isotype

The rapid development of vaccines to prevent infection by SARS-CoV-2 virus causing COVID-19 makes necessary to compare the capacity of the different vaccines in terms of development of a protective humoral response. Here, we have used a highly sensitive and reliable flow cytometry method to measure the titers of antibodies of the IgG1 isotype in blood of volunteers after receiving one or two doses of the vaccines being administered in Spain. We took advantage of the multiplexed capacity of the method to measure simultaneously the reactivity of antibodies with the S protein of the original strain Wuhan-1 and the variant B.1.1.7 (Alpha). We found significant differences in the titer of anti-S antibodies produced after a first dose of the vaccines ChAdOx1 nCov-19/AstraZeneca, mRNA-1273/Moderna, BNT162b2/Pfizer-BioNTech and Ad26.COV.S/Janssen. Most important, we found a relative reduction in the reactivity of the sera with the B.1.1.7 versus the Wuhan-1 variant after the second boosting immunization. These data allow to make a comparison of different vaccines in terms of anti-S antibody generation and cast doubts about the convenience of repeatedly immunizing with the same S protein sequence.

scholarly journals American tegumentary leishmaniasis diagnosis using L. (V.) braziliensis fixed promastigotes: a comparative performance of serological tests and spontaneous cure identification

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Andresa Pereira Oliveira Mendes ◽  
Beatriz Coutinho Oliveira ◽  
Allana Maria S. Pereira ◽  
Maria Carolina Accioly Brelaz Castro ◽  
Marina Assis Souza ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Immunoglobulin G ◽  
Humoral Response ◽  
Post Treatment ◽  
Serological Tests ◽  
Comparative Performance ◽  
Tegumentary Leishmaniasis ◽  
Spontaneous Cure ◽  
American Tegumentary Leishmaniasis ◽  
Igg1 Isotype

Abstract Background The present study aimed to demonstrate the applicability of a flow cytometry-based serology approach to identify spontaneous cure by the detection of immunoglobulin G, and also, the diagnosis and cure criterion by the IgG1 isotype in American Tegumentary Leishmaniasis – ATL caused by L. (V.) braziliensis. Also, a comparison between flow cytometry with the serological conventional technique was performed. Methods Forty five individuals were included in study. They were assessed in two moments: First, 8 subjects spontaneously cured of ATL, 8 healthy individuals and 15 patients who had a positive diagnosis for ATL were selected before treatment to identify spontaneous cure by immunoglobulin G detection. Secondly, 14 patients who were positive for ATL were selected and had their blood collected before and 1, 2 and 5 years after treatment, respectively, for the diagnostic tests (ELISA and flow cytometry) and cure criterion evaluation using the IgG1 isotype. Results The analysis of the mean percentage of positive fluorescent parasites (PPFP) along with the titration curves of IgG anti-fixed promastigotes of L.(V.)braziliensis, confirmed the applicability of this method for monitoring spontaneous cure in ATL with outstanding co-positivity (100%) and co-negativity (100%) performance indexes. Regarding the results of the comparison between flow cytometry and ELISA it was seen that there was a better accuracy of the first one in relation to the other. When IgG1 applicability was evaluated, it was observed that before treatment, 36.8% of the patients were negative; in patients 1 year post-treatment, 82.3%; 2 years post-treatment, 27.2% and in patients 5 years post-treatment, 87.5%. The overall analysis of the results suggests that flow cytometry can be applied to ATL detection, and that the use of IgG1 isotype has possibilities to contribute as a more specific diagnostic method. Conclusions Therefore, this area has great perspectives use for the diagnosis and cure criterion, and also it can be scaled up with the possibility to characterize the different clinical stages of the disease. Together, these findings demonstrate the applicability of a flow cytometry-based serology approach and opens up new avenues of research with this technique, such as the understanding the humoral response in ATL patients.

scholarly journals Structural Analysis of the SARS-CoV-2 Omicron Variant Proteins

Research ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-4
Author(s):  
Qiangzhen Yang ◽  
Ali Alamdar Shah Syed ◽  
Aamir Fahira ◽  
Yongyong Shi
Keyword(s):  
Amino Acids ◽  
Phylogenetic Analysis ◽  
Structural Analysis ◽  
Protein Sequence ◽  
Immune Escape ◽  
Protein Structures ◽  
The Other ◽  
Original Strain ◽  
S Protein ◽  
Future Studies

The spread of the latest SARS-CoV-2 variant Omicron is particularly concerning because of the large number of mutations present in its genome and lack of knowledge about how these mutations would affect the current SARS-CoV-2 vaccines and treatments. Here, by performing phylogenetic analysis using the Omicron spike (S) protein sequence, we found that the Omicron S protein presented the longest evolutionary distance in relation to the other SARS-CoV-2 variants. We predicted the structures of S, M, and N proteins of the Omicron variant using AlphaFold2 and investigated how the mutations have affected the S protein and its parts, S1 NTD and RBD, in detail. We found many amino acids on RBD were mutated, which may influence the interactions between the RBD and ACE2, while also showing the S309 antibody could still be capable of neutralizing Omicron RBD. The Omicron S1 NTD structures display significant differences from the original strain, which could lead to reduced recognition by antibodies resulting in potential immune escape and decreased effectiveness of the existing vaccines. However, this study of the Omicron variant was mainly limited to structural predictions, and these findings should be explored and verified by subsequent experiments. This study provided basic data of the Omicron protein structures that lay the groundwork for future studies related to the SARS-CoV-2 Omicron variant.

Cancer Proteomics: New Horizons and Insights into Therapeutic Applications

2020 ◽  
Vol 17 ◽  
Author(s):  
Perumal Subramaniana ◽  
Jaime Jacqueline Jayapalan ◽  
Puteri Shafinaz Abdul-Rahmanb
Keyword(s):  
Molecular Mechanisms ◽  
Rapid Development ◽  
New Horizons ◽  
Cancer Management ◽  
Proteomic Approach ◽  
Cancer Proteomics ◽  
Therapeutic Outcomes ◽  
A Genome ◽  
Highly Sensitive ◽  
Dimensional Electrophoresis

A proteome is an efficient rendition of a genome, unswervingly controlling various cancer processes. Molecular mechanisms of several cancer processes have been unraveled by proteomic approach. Thus far, numerous tumors of diverse status have been investigated by two-dimensional electrophoresis. Numerous biomarkers have been recognized and precise categorization of apparent lesions has led to the timely detection of various cancers in persons at peril. Currently used pioneering approaches and technologies in proteomics have led to highly sensitive assays of cancer biomarkers and improved the early diagnosis of various cancers. The discovery of novel and definite biomarker signatures further widened our perceptive of the disease and novel potent drugs for efficient and aimed therapeutic outcomes in persistent cancers have emerged. However, a major limitation, even today, of proteomics is resolving and quantifying the proteins of low abundance. Despite the rapid development of proteomic technologies and their applications in cancer management, annulling the shortcomings of present proteomic technologies and development of better methods are still desirable. The main objectives of this review are to discuss the developing aspects, merits and demerits of pharmacoproteomics, redox proteomics, novel approaches and therapies being used for various types of cancer based on proteome studies.

scholarly journals The Functional Consequences of the Novel Ribosomal Pausing Site in SARS-CoV-2 Spike Glycoprotein RNA

2021 ◽  
Vol 22 (12) ◽  
pp. 6490
Author(s):  
Olga A. Postnikova ◽  
Sheetal Uppal ◽  
Weiliang Huang ◽  
Maureen A. Kane ◽  
Rafael Villasmil ◽  
...  
Keyword(s):  
Amino Acid ◽  
Insertion Sequence ◽  
Experimental Studies ◽  
Spike Protein ◽  
Spike Glycoprotein ◽  
Furin Cleavage ◽  
New Host ◽  
S Protein ◽  
Furin Cleavage Site ◽  
Ribosome Pausing

The SARS-CoV-2 Spike glycoprotein (S protein) acquired a unique new 4 amino acid -PRRA- insertion sequence at amino acid residues (aa) 681–684 that forms a new furin cleavage site in S protein as well as several new glycosylation sites. We studied various statistical properties of the -PRRA- insertion at the RNA level (CCUCGGCGGGCA). The nucleotide composition and codon usage of this sequence are different from the rest of the SARS-CoV-2 genome. One of such features is two tandem CGG codons, although the CGG codon is the rarest codon in the SARS-CoV-2 genome. This suggests that the insertion sequence could cause ribosome pausing as the result of these rare codons. Due to population variants, the Nextstrain divergence measure of the CCU codon is extremely large. We cannot exclude that this divergence might affect host immune responses/effectiveness of SARS-CoV-2 vaccines, possibilities awaiting further investigation. Our experimental studies show that the expression level of original RNA sequence “wildtype” spike protein is much lower than for codon-optimized spike protein in all studied cell lines. Interestingly, the original spike sequence produces a higher titer of pseudoviral particles and a higher level of infection. Further mutagenesis experiments suggest that this dual-effect insert, comprised of a combination of overlapping translation pausing and furin sites, has allowed SARS-CoV-2 to infect its new host (human) more readily. This underlines the importance of ribosome pausing to allow efficient regulation of protein expression and also of cotranslational subdomain folding.

scholarly journals Conventional, High-Resolution and Imaging Flow Cytometry: Benchmarking Performance in Characterisation of Extracellular Vesicles

Biomedicines ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 124
Author(s):  
Jaco Botha ◽  
Haley R. Pugsley ◽  
Aase Handberg
Keyword(s):  
Flow Cytometry ◽  
High Resolution ◽  
Extracellular Vesicles ◽  
Single Particles ◽  
Multiple Parameters ◽  
Imaging Flow Cytometry ◽  
Highly Sensitive ◽  
Individual Project ◽  
Benchmarking Performance ◽  
High Throughput Manner

Flow cytometry remains a commonly used methodology due to its ability to characterise multiple parameters on single particles in a high-throughput manner. In order to address limitations with lacking sensitivity of conventional flow cytometry to characterise extracellular vesicles (EVs), novel, highly sensitive platforms, such as high-resolution and imaging flow cytometers, have been developed. We provided comparative benchmarks of a conventional FACS Aria III, a high-resolution Apogee A60 Micro-PLUS and the ImageStream X Mk II imaging flow cytometry platform. Nanospheres were used to systematically characterise the abilities of each platform to detect and quantify populations with different sizes, refractive indices and fluorescence properties, and the repeatability in concentration determinations was reported for each population. We evaluated the ability of the three platforms to detect different EV phenotypes in blood plasma and the intra-day, inter-day and global variabilities in determining EV concentrations. By applying this or similar methodology to characterise methods, researchers would be able to make informed decisions on choice of platforms and thereby be able to match suitable flow cytometry platforms with projects based on the needs of each individual project. This would greatly contribute to improving the robustness and reproducibility of EV studies.

Smartphone Based Highly Sensitive Visualized Detection of Acid Phosphatase Enzyme Activity

2021 ◽  
Author(s):  
Rui Li ◽  
Yanan Sun ◽  
Lihua Jin ◽  
Xiaohong Qiao ◽  
Cong Li ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Acid Phosphatase ◽  
Point Of Care ◽  
Rapid Development ◽  
Practical Application ◽  
Fast Analysis ◽  
Highly Sensitive ◽  
Visualized Detection ◽  
Sensitive Method ◽  
Phosphatase Enzyme

With the rapid development of point-of-care (POC) technologies, the improvement of sensitive method featured with fast analysis and affordable devices has become an emerging requirement for the practical application. In...

DNA-Directed Patterning for Versatile Validation and Characterization of a Lipid-Based Nanoparticle Model of SARS-CoV-2

2021 ◽  
Author(s):  
Molly Kozminsky ◽  
Thomas Carey ◽  
Lydia L. Sohn
Keyword(s):  
High Throughput ◽  
Glass Substrate ◽  
Rapid Development ◽  
Neutralizing Antibody ◽  
S Protein ◽  
Biological Relevance ◽  
The Face ◽  
Great Control ◽  
Tetraspanin Cd63

Lipid-based nanoparticles have risen to the forefront of the COVID-19 pandemic—from encapsulation of vaccine components to modeling the virus, itself. Their rapid development in the face of the volatile nature of the pandemic requires high-throughput, highly flexible methods for characterization. DNA-directed patterning is a versatile method to immobilize and segregate lipid-based nanoparticles for subsequent analysis. DNA-directed patterning selectively conjugates oligonucleotides onto a glass substrate and then hybridizes them to complementary oligonucleotides tagged to the liposomes, thereby patterning them with great control and precision. The power of this method is demonstrated by characterizing a novel recapitulative lipid-based nanoparticle model of SARS-CoV-2 —S-liposomes— which present the SARS-CoV-2 spike (S) protein on their surfaces. Patterning of a mixture of S-liposomes and liposomes that display the tetraspanin CD63 into discrete regions of a substrate is used to show that ACE2 specifically binds to S-liposomes. Importantly, DNA-directed patterning of S-liposomes is used to verify the performance of a commercially available neutralizing antibody against the S protein. Ultimately, the introduction of S-liposomes to ACE2-expressing cells demonstrates the biological relevance of DNA-directed patterning. Overall, DNA-directed patterning enables a wide variety of custom assays for the characterization of any lipid-based nanoparticle.

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