scholarly journals Bamlanivimab does not neutralize two SARS-CoV-2 variants carrying E484K in vitro

2021 ◽  
Author(s):  
Marek Widera ◽  
Alexander Wilhelm ◽  
Sebastian Hoehl ◽  
Christiane Pallas ◽  
Niko Kohmer ◽  
...  
Keyword(s):  
Cell Culture ◽  
Monoclonal Antibody ◽  
Human Cells ◽  
Viral Attachment ◽  
Neutralizing Activity ◽  
Caco2 Cells ◽  
Igg1 Monoclonal Antibody

The IgG1 monoclonal antibody (mAb) bamlanivimab (LY-CoV555) prevents viral attachment and entry into human cells by blocking attachment to the ACE2 receptor. However, whether bamlanivimab is equally effective against SARS-CoV-2 emerging variants of concern (VOC) is not fully known. Hence, the aim of this study was to determine whether bamlanivimab is equally effective against SARS-CoV-2 emerging VOC. The ability of bamlanivimab to neutralize five SARS-CoV-2 variants including B.1.1.7 (mutations include N501Y and del69/70), B.1.351 (mutations include E484K and N501Y) and P.2 (mutations include E484K in the absence of a N501Y mutation) was analyzed in infectious cell culture using CaCo2 cells. Additionally, we analyzed vaccine-elicited sera after immunization with BNT162b2, and convalescent sera for its ability to neutralize SARS-CoV-2 variants. We found that the variant B.1.1.7, as well as two isolates from early 2020 (FFM1 and FFM7) could be efficiently neutralized by bamlanivimab (titer 1/1280, respectively), however, no neutralization effect could be detected against either B.1.135 or P.2, both harboring the E484K substitution. Vaccine-elicited sera showed slightly decreased neutralizing activity against B1.1.7, B.1.135 and P.2 Our in vitro findings indicate that, in contrast to vaccine-elicited sera, bamlanivimab may not provide efficacy against SARS-CoV-2 variants harboring the E484K substitution. Confirmation of the SARS-CoV-2 variant, including screening for E484K, may be needed before initiating mAb treatment with bamlanivimab to ensure both efficacious and efficient use of the antibody product. Hence, variant-specific mAb agents may be required to treat emerging VOC.

scholarly journals Delivery of functional exogenous proteins by plant-derived vesicles to human cells in vitro

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Luiza Garaeva ◽  
Roman Kamyshinsky ◽  
Yury Kil ◽  
Elena Varfolomeeva ◽  
Nikolai Verlov ◽  
...  
Keyword(s):  
Cell Culture ◽  
Colon Cancer ◽  
Extracellular Vesicles ◽  
Mononuclear Cells ◽  
Human Peripheral Blood ◽  
Human Cells ◽  
Bioactive Molecules ◽  
Native Plant ◽  
Peripheral Blood Mononuclear

AbstractPlant-derived extracellular vesicles (EVs) gain more and more attention as promising carriers of exogenous bioactive molecules to the human cells. Derived from various edible sources, these EVs are remarkably biocompatible, biodegradable and highly abundant from plants. In this work, EVs from grapefruit juice were isolated by differential centrifugation followed by characterization of their size, quantity and morphology by nanoparticle tracking analysis, dynamic light scattering, atomic force microscopy and cryo-electron microscopy (Cryo-EM). In Cryo-EM experiments, we visualized grapefruit EVs with the average size of 41 ± 13 nm, confirmed their round-shaped morphology and estimated the thickness of their lipid bilayer as 5.3 ± 0.8 nm. Further, using cell culture models, we have successfully demonstrated that native grapefruit-derived extracellular vesicles (GF-EVs) are highly efficient carriers for the delivery of the exogenous Alexa Fluor 647 labeled bovine serum albumin (BSA) and heat shock protein 70 (HSP70) into both human peripheral blood mononuclear cells and colon cancer cells. Interestingly, loading to plant EVs significantly ameliorated the uptake of exogenous proteins by human cells compared to the same proteins without EVs. Most importantly, we have confirmed the functional activity of human recombinant HSP70 in the colon cancer cell culture upon delivery by GF-EVs. Analysis of the biodistribution of GF-EVs loaded with 125I-labeled BSA in mice demonstrated a significant uptake of the grapefruit-derived extracellular vesicles by the majority of organs. The results of our study indicate that native plant EVs might be safe and effective carriers of exogenous proteins into human cells.

scholarly journals In Vitro and In Vivo Fitness of Respiratory Syncytial Virus Monoclonal Antibody Escape Mutants

2006 ◽  
Vol 80 (23) ◽  
pp. 11651-11657 ◽  
Author(s):  
Xiaodong Zhao ◽  
Enmei Liu ◽  
Fu-Ping Chen ◽  
Wayne M. Sullender
Keyword(s):  
Cell Culture ◽  
Monoclonal Antibody ◽  
Respiratory Syncytial Virus ◽  
Viral Population ◽  
Nucleotide Substitutions ◽  
Cotton Rats ◽  
Syncytial Virus ◽  
In Vivo Growth

ABSTRACT Respiratory syncytial virus (RSV) is the only infectious disease for which a monoclonal antibody (MAb) is used in humans. Palivizumab (PZ) is a humanized murine MAb to the F protein of RSV. PZ-resistant viruses appear after in vitro and in vivo growth of RSV in the presence of PZ. Fitness for replication could be a determinant of the likelihood of dissemination of resistant viruses. We assessed the fitness of two PZ-resistant viruses (F212 and MP4). F212 grew less well in cell culture than the parent A2 virus and was predicted to be less fit than A2. Equal amounts of F212 and A2 were mixed and passaged in cell culture. F212 disappeared from the viral population, indicating it was less fit than the A2 virus. The MP4 virus grew as well as A2 in culture and in cotton rats. A2/MP4 virus input ratios of 1:1, 10:1, 100:1, and 1,000:1 were compared in competitive replication. For all input ratios except 1,000:1, the MP4 virus became dominant, supplanting the A2 virus. The MP4 virus also dominated the A2 virus during growth in cotton rats. Thus, the mutant MP4 virus was more fit than A2 virus in both in vitro and in vivo competitive replication. Whether this fitness difference was due to the identified nucleotide substitutions in the F gene or to mutations elsewhere in the genome is unknown. Understanding the mechanisms by which mutant virus fitness increased or decreased could prove useful for consideration in attenuated vaccine design efforts.

A Structure-Function Study of the Activity of Stem Cell Factor in Stimulating the Expansion of Cord Blood CD34+ Cells

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3501-3501
Author(s):  
Bin Shen ◽  
Wenhong Jiang ◽  
Jie Fan ◽  
Wei Dai ◽  
Xinxin Ding ◽  
...  
Keyword(s):  
Cell Culture ◽  
Monoclonal Antibody ◽  
Stem Cell ◽  
Stem Cell Factor ◽  
Culture Medium ◽  
Cell Number ◽  
Full Length ◽  
Cell Culture Medium ◽  
Cd34 Cells

Abstract Stem cell factor is one of the most important growth factors for human hematopoietic stem cells (HSC). Recombinant human stem cell factor (rhSCF) can stimulate HSC expansion and regeneration in vitro, when it is used in combination with other cytokines like Flt-3L and TPO. However, the specific structural region(s) of the rhSCF protein that are critical for its function in HSC expansion are still unknown. Few studies have addressed this problem, to date. We have recently reported the production of a novel monoclonal antibody (named 23C8) against rhSCF, and the demonstration that 23C8 could inhibit the ability of rhSCF to enhance HSC expansion. Here, we report the identification of a short polypeptide from rhSCF that contains the epitope for binding to 23C8, and, like the full-length rhSCF, is able to stimulate the expansion of umbilical cord blood (UCB)-derived CD34+ cells. Twelve short polypeptides were designed and synthesized, which cover the full length of rhSCF, with 3-5 amino acids overlaps. 23C8 was collected from hybridoma cell culture medium and further purified using protein G affinity chromatography. ELISA was used to identify the polypeptide(s) that positively react with 23C8 among all the synthesized polypeptides. In addition, the effects of the synthetic polypeptides on human HSC expansion capacity were evaluated by supplementing the cell culture medium with 100 ng/ml of a given polypeptide. Total cell number and CD34+ cell number of each group were monitored on day 6. Our novel anti-SCF monoclonal antibody (23C8) partially blocked SCF’s function in human UCB CD34+ cell expansion. Of all the polypeptides analyzed, only one, named P0, corresponding to the SCF protein sequence at residues 40 to 57, was recognized by 23C8 during ELISA. P0, like the full-length rhSCF, enhanced expansion of CD34+ cells derived from human UCB. P0 addition increased the numbers of total nucleated cells and CD34+ cells by 10.58±0.86 and 4.63±0.43 folds, respectively. For comparison, the extents of increases in cell numbers in the vehicle control group was 3.15±0.99 fold (total nucleated cells) and 1.07±0.11 fold (CD34+ cells), respectively. Residues 40-57 of hrSCF comprise a critical functional region for its ability to enhance expansion of human UCB CD34+ cells in vitro. The short P0 peptide is a potential candidate for development as a synthetic substitute for rhSCF in clinic applications. Disclosures Jiang: Biopharmagen.corp: Employment. Jiang:Biopharmagen.corp: Employment.

scholarly journals MTX-COVAB, a human-derived antibody with potent neutralizing activity against SARS-CoV-2 infection in vitro and in a hamster model of COVID-19

2020 ◽  
Author(s):  
Simone Schmitt ◽  
Marcel Weber ◽  
Matthias Hillenbrand ◽  
Jemima Seidenberg ◽  
Andreas Zingg ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Fast Track ◽  
Neutralization Assay ◽  
Hamster Model ◽  
Neutralizing Activity ◽  
Antibody Repertoires

AbstractFast track microfluidic screening of the antibody repertoires of 12 convalescent COVID-19 donors comprising 2.8mio antibodies yielded MTX-COVAB, a human-derived monoclonal antibody with low picomolar neutralization IC50 of SARS-CoV-2. COVAB neutralization potency is on par with the Regeneron cocktail as demonstrated in a comparative neutralization assay. MTX-COVAB shows strong efficacy in vivo and binds to all currently identified clinically relevant variants of SARS-CoV-2. MTX-COVAB completes GMP manufacturing by the end of this year and will be tested in the clinic in March 2021.

scholarly journals Generation and characterization of cross neutralizing human monoclonal antibody against 4 serotypes of dengue virus without enhancing activity

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4021 ◽  
Author(s):  
Subenya Injampa ◽  
Nataya Muenngern ◽  
Chonlatip Pipattanaboon ◽  
Surachet Benjathummarak ◽  
Khwanchit Boonha ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Dengue Virus ◽  
Mammalian Cells ◽  
Human Monoclonal Antibody ◽  
Site Directed Mutagenesis ◽  
Neutralizing Activity ◽  
Dengue Disease ◽  
Denv Serotypes ◽  
Fusion Loop

Background Dengue disease is a leading cause of illness and death in the tropics and subtropics. Most severe cases occur among patients secondarily infected with a different dengue virus (DENV) serotype compared with that from the first infection, resulting in antibody-dependent enhancement activity (ADE). Our previous study generated the neutralizing human monoclonal antibody, D23-1B3B9 (B3B9), targeting the first domain II of E protein, which showed strong neutralizing activity (NT) against all four DENV serotypes. However, at sub-neutralizing concentrations, it showed ADE activity in vitro. Methods In this study, we constructed a new expression plasmid using the existing IgG heavy chain plasmid as a template for Fc modification at position N297Q by site-directed mutagenesis. The resulting plasmid was then co-transfected with a light chain plasmid to produce full recombinant IgG (rIgG) in mammalian cells (N297Q-B3B9). This rIgG was characterized for neutralizing and enhancing activity by using different FcγR bearing cells. To produce sufficient quantities of B3B9 rIgG for further characterization, CHO-K1 cells stably secreting N297Q-B3B9 rIgG were then established. Results The generated N297Q-B3B9 rIgG which targets the conserved N-terminal fusion loop of DENV envelope protein showed the same cross-neutralizing activity to all four DENV serotypes as those of wild type rIgG. In both FcγRI- and RII-bearing THP-1 cells and FcγRII-bearing K562 cells, N297Q-B3B9 rIgG lacked ADE activity against all DENV serotypes at sub-neutralizing concentrations. Fortunately, the N297Q-B3B9 rIgG secreted from stable cells showed the same patterns of NT and ADE activities as those of the N297Q-B3B9 rIgG obtained from transient expression against DENV2. Thus, the CHO-K1 stably expressing N297Q-B3B9 HuMAb can be developed as high producer stable cells and used to produce sufficient amounts of antibody for further characterization as a promising dengue therapeutic candidate. Discussion Human monoclonal antibody, targeted to fusion loop of envelope domainII (EDII), was generated and showed cross-neutralizing activity to 4 serotypes of DENV, but did not cause any viral enhancement activity in vitro. This HuMAb could be further developed as therapeutic candidates.

1120: Citrate and Vitamin E Blunt the SWL-Induced Free Radical Surge in an In-Vitro MDCK Cell Culture Model

2004 ◽  
Vol 171 (4S) ◽  
pp. 295-295
Author(s):  
Fernando C. Delvecchio ◽  
Ricardo M. Brizuela ◽  
Karen J. Byer ◽  
W. Patrick Springhart ◽  
Saeed R. Khan ◽  
...  
Keyword(s):  
Cell Culture ◽  
Free Radical ◽  
Vitamin E ◽  
Mdck Cell ◽  
Cell Culture Model ◽  
Culture Model

3D in vitro reconstruction of synthetic liver sinusoids in a microfluidic cell culture device

2013 ◽  
Vol 51 (01) ◽  
Author(s):  
J Böttger ◽  
J Schütte ◽  
K Benz ◽  
C Freudigmann ◽  
B Hagmeyer ◽  
...  
Keyword(s):  
Cell Culture ◽  
Liver Sinusoids ◽  
Microfluidic Cell Culture

The Anticoagulant Properties of a Modified Form of Protein S

1988 ◽  
Vol 60 (02) ◽  
pp. 298-304 ◽  
Author(s):  
C A Mitchell ◽  
S M Kelemen ◽  
H H Salem
Keyword(s):  
Monoclonal Antibody ◽  
Anticoagulant Activity ◽  
Activated Protein C ◽  
Factor Xa ◽  
Protein S ◽  
Human Neutrophil Elastase ◽  
Factor X ◽  
Sds Page

SummaryProtein S (PS) is a vitamin K-dependent anticoagulant that acts as a cofactor to activated protein C (APC). To date PS has not been shown to possess anticoagulant activity in the absence of APC.In this study, we have developed monoclonal antibody to protein S and used to purify the protein to homogeneity from plasma. Affinity purified protein S (PSM), although identical to the conventionally purified protein as judged by SDS-PAGE, had significant anticoagulant activity in the absence of APC when measured in a factor Xa recalcification time. Using SDS-PAGE we have demonstrated that prothrombin cleavage by factor X awas inhibited in the presence of PSM. Kinetic analysis of the reaction revealed that PSM competitively inhibited factor X amediated cleavage of prothrombin. PS preincubated with the monoclonal antibody, acquired similar anticoagulant properties. These results suggest that the interaction of the monoclonal antibody with PS results in an alteration in the protein exposing sites that mediate the observed anticoagulant effect. Support that the protein was altered was derived from the observation that PSM was eight fold more sensitive to cleavage by thrombin and human neutrophil elastase than conventionally purified protein S.These observations suggest that PS can be modified in vitro to a protein with APC-independent anticoagulant activity and raise the possibility that a similar alteration could occur in vivo through the binding protein S to a cellular or plasma protein.

IN VITRO METHODS FOR THE STUDY OF THE ADENOHYPOPHYSIAL FUNCTIONS TO SECRETE GONADOTROPHIN

1971 ◽  
Vol 68 (1_Suppl) ◽  
pp. S27-S40 ◽  
Author(s):  
T. Kobayashi ◽  
T. Kigawa ◽  
M. Mizuno ◽  
T. Watanabe
Keyword(s):  
Cell Culture ◽  
Organ Culture ◽  
Cultured Cells ◽  
Cell Sheet ◽  
Short Term ◽  
Hypothalamic Extract ◽  
Numerous Cell ◽  
Single Cell Culture ◽  
Almost All

ABSTRACT There are several in vitro methods to analyse the function of the adenohypophysis or the mechanisms of its regulation. The present paper deals with single cell culture, organ culture and short term incubation techniques by which the morphology and gonadotrophin-secreting function of the adenohypophysis were studied. In trypsin-dispersed cell culture, the adenohypophysial cells showed extensive propagation to form numerous cell colonies and finally develop into a confluent monolayer cell sheet covering completely the surface of culture vessels. Almost all of the cultured cells, however, became chromophobic, at least at the end of the first week of cultivation, when gonadotrophin was detectable neither in the culture medium nor in the cells themselves. After the addition of the hypothalamic extract, gonadotrophin became detectable again, and basophilic or PAS-positive granules also reappeared within the cells, suggesting that the gonadotrophs were stimulated by the extract to produce gonadotrophin. In organ culture and short term incubation, the incorporation of [3H] leucine into the adenohypophysial cells in relation to the addition of hypothalamic extract was examined. It was obvious that the ability to incorporate [3H] leucine into the gonadotrophs in vitro was highly dependent upon the presence of the hypothalamic extract.

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