scholarly journals A Simple Model for Assessment of Anti-Toxin Antibodies

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Alex Skvortsov ◽  
Peter Gray
Keyword(s):  
In Vitro Selection ◽  
Receptor Complex ◽  
Simple Mathematical Model ◽  
Antibody Affinity ◽  
In Vivo Evaluation ◽  
Degree Of Protection ◽  
Protective Antibodies ◽  
Selection Of

The toxins associated with infectious diseases are potential targets for inhibitors which have the potential for prophylactic or therapeutic use. Many antibodies have been generated for this purpose, and the objective of this study was to develop a simple mathematical model that may be used to evaluate the potential protective effect of antibodies. This model was used to evaluate the contributions of antibody affinity and concentration to reducing antibody-receptor complex formation and internalization. The model also enables prediction of the antibody kinetic constants and concentration required to provide a specified degree of protection. We hope that this model, once validated experimentally, will be a useful tool for in vitro selection of potentially protective antibodies for progression to in vivo evaluation.

scholarly journals Robotic QM/MM-driven maturation of antibody combining sites

2016 ◽  
Vol 2 (10) ◽  
pp. e1501695 ◽  
Author(s):  
Ivan V. Smirnov ◽  
Andrey V. Golovin ◽  
Spyros D. Chatziefthimiou ◽  
Anastasiya V. Stepanova ◽  
Yingjie Peng ◽  
...  
Keyword(s):  
Immune Response ◽  
In Vitro Selection ◽  
Single Point ◽  
Combinatorial Libraries ◽  
Single Point Mutation ◽  
Wild Type ◽  
Selection Of ◽  
Maturation Function

In vitro selection of antibodies from large repertoires of immunoglobulin (Ig) combining sites using combinatorial libraries is a powerful tool, with great potential for generating in vivo scavengers for toxins. However, addition of a maturation function is necessary to enable these selected antibodies to more closely mimic the full mammalian immune response. We approached this goal using quantum mechanics/molecular mechanics (QM/MM) calculations to achieve maturation in silico. We preselected A17, an Ig template, from a naïve library for its ability to disarm a toxic pesticide related to organophosphorus nerve agents. Virtual screening of 167,538 robotically generated mutants identified an optimum single point mutation, which experimentally boosted wild-type Ig scavenger performance by 170-fold. We validated the QM/MM predictions via kinetic analysis and crystal structures of mutant apo-A17 and covalently modified Ig, thereby identifying the displacement of one water molecule by an arginine as delivering this catalysis.

In vitro Selection of a Peptide with High Selectivity for Cardiomyocytes In vivo

2004 ◽  
Vol 342 (1) ◽  
pp. 171-182 ◽  
Author(s):  
Michael J. McGuire ◽  
Kausar N. Samli ◽  
Stephen Albert Johnston ◽  
Kathlynn C. Brown
Keyword(s):  
In Vitro Selection ◽  
High Selectivity ◽  
Selection Of

scholarly journals In Vitro and In Vivo Stability a Cryptococcus neoformans Glucuronoxylomannan Epitope That Elicits Protective Antibodies

1999 ◽  
Vol 67 (6) ◽  
pp. 3096-3107 ◽  
Author(s):  
Wendy Cleare ◽  
Robert Cherniak ◽  
Arturo Casadevall
Keyword(s):  
Cryptococcus Neoformans ◽  
Parent Strain ◽  
Marked Reduction ◽  
Murine Models ◽  
Clear Trend ◽  
Agglutination Assay ◽  
Protective Antibodies ◽  
Selection Of

ABSTRACT The monoclonal antibody (MAb) 2H1 defines an epitope inCryptococcus neoformans capsular glucuronoxylomannan (GXM) that can elicit protective antibodies. In murine models of cryptococcosis, MAb 2H1 administration prolongs survival and reduces fungal burden but seldom clears the infection. The mechanism by whichC. neoformans persists and escape antibody-mediated clearance is not understood. One possibility is that variants that do not bind MAb 2H1 emerge in the course of infection. Using an agglutination-sedimentation protocol, we recovered a variant of strain 24067 that did not agglutinate, could not be serotyped, and had marked reduction in GXM O-acetyl groups. Binding of MAb 2H1 to 24067 variant cells produced a different immunofluorescence pattern and lower fluorescence intensity relative to the parent 24067 cells. Addition of MAb 2H1 to 24067 variant cells had no effect on cell charge. Phagocytic assays demonstrated that MAb 2H1 was not an effective opsonin for the 24067 variant. The 24067 variant was less virulent than the 24067 parent strain in mice, and MAb 2H1 administration did not prolong survival in animals infected with the variant strain. To investigate whether variants which do not bind MAb 2H1 are selected in experimental infection, three C. neoformans strains were serially passaged in mice given either MAb 2H1 or no antibody. Analysis of passaged isolates by agglutination assay, flow cytometry, and indirect immunofluorescence revealed changes in MAb 2H1 epitope expression but no clear trend with regards to gain or loss of MAb 2H1 epitope. C. neoformans variants with reduced MAb 2H1 epitope content can be isolated in vitro, but persistence of infection in mice given MAb 2H1 does not appear to be a result of selection of escape variants that lack the MAb 2H1 epitope.

scholarly journals In-Vitro Selection of Ceftazidime/Avibactam Resistance in OXA-48-Like-Expressing Klebsiella pneumoniae: In-Vitro and In-Vivo Fitness, Genetic Basis and Activities of β-Lactam Plus Novel β-Lactamase Inhibitor or β-Lactam Enhancer Combinations

Antibiotics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1318
Author(s):  
Snehal Palwe ◽  
Yamuna Devi Bakthavatchalam ◽  
Kshama Khobragadea ◽  
Arun S. Kharat ◽  
Kamini Walia ◽  
...  
Keyword(s):  
In Vitro Selection ◽  
Whole Genome Sequence ◽  
Serial Transfer ◽  
Resistance Selection ◽  
Clinical Resistance ◽  
Growth Properties ◽  
Outer Membrane Permeability ◽  
Selection Of

Ceftazidime/avibactam uniquely demonstrates activity against both KPC and OXA-48-like carbapenemase-expressing Enterobacterales. Clinical resistance to ceftazidime/avibactam in KPC-producers was foreseen in in-vitro resistance studies. Herein, we assessed the resistance selection propensity of ceftazidime/avibactam in K. pneumoniae expressing OXA-48-like β-lactamases (n = 10), employing serial transfer approach. Ceftazidime/avibactam MICs (0.25–4 mg/L) increased to 16–256 mg/L after 15 daily-sequential transfers. The whole genome sequence analysis of terminal mutants showed modifications in proteins linked to efflux (AcrB/AcrD/EmrA/Mdt), outer membrane permeability (OmpK36) and/or stress response pathways (CpxA/EnvZ/RpoE). In-vitro growth properties of all the ceftazidime/avibactam-selected mutants were comparable to their respective parents and they retained the ability to cause pulmonary infection in neutropenic mice. Against these mutants, we explored the activities of various combinations of β-lactams (ceftazidime or cefepime) with structurally diverse β-lactamase inhibitors or a β-lactam enhancer, zidebactam. Zidebactam, in combination with either cefepime or ceftazidime, overcame ceftazidime/avibactam resistance (MIC range 0.5–8 mg/L), while cefepime/avibactam was the second best (MIC: 0.5–16 mg/L) in yielding lower MICs. The present work revealed the possibility of ceftazidime/avibactam resistance in OXA-48-like K. pneumoniae through mutations in proteins involved in efflux and/or porins without concomitant fitness cost mandating astute monitoring of ceftazidime/avibactam resistance among OXA-48 genotypes.

scholarly journals Selection of Water-Soluble Chitosan by Microwave-Assisted Degradation and pH-Controlled Precipitation

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1274 ◽  
Author(s):  
Céline M. A. Journot ◽  
Laura Nicolle ◽  
Yann Lavanchy ◽  
Sandrine Gerber-Lemaire
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Aqueous Media ◽  
Phase Changes ◽  
Water Soluble ◽  
In Vivo Evaluation ◽  
Microwave Assisted ◽  
Selection Of

In the field of gene therapy, chitosan (CS) gained interest for its promise as a non-viral DNA vector. However, commercial sources of CS lack precise characterization and do not generally reach sufficient solubility in aqueous media for in vitro and in vivo evaluation. As low molecular weight CS showed improved solubility, we investigated the process of CS depolymerization by acidic hydrolysis, using either long time heating at 80 °C or short time microwave-enhanced heating. The resulting depolymerized chitosan (dCS) were analyzed by gel permeation chromatography (GPC) and 1H nuclear magnetic resonance (NMR) to determine their average molecular weight (Mn, Mp and Mw), polydispersity index (PD) and degree of deacetylation (DD). We emphasized the production of water-soluble CS (solubility > 5 mg/mL), obtained in reproducible yield and characteristics, and suitable for downstream functionalization. Optimal microwave-assisted conditions provided dCS with a molecular weight (MW) = 12.6 ± 0.6 kDa, PD = 1.41 ± 0.05 and DD = 85%. While almost never discussed in the literature, we observed the partial post-production aggregation of dCS when exposed to phase changes (from liquid to solid). Repeated cycles of freezing/thawing allowed the selection of dCS fractions which were exempt of crystalline particles formation upon solubilization from frozen samples.

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