scholarly journals A simple and safe antibody neutralization assay based on polio pseudoviruses

2018 ◽  
Vol 15 (2) ◽  
pp. 349-357 ◽  
Author(s):  
Zheng Jiang ◽  
Guixiu Liu ◽  
Liao Guo-yang ◽  
Mingbo Sun ◽  
Kangwei Xu ◽  
...  
Keyword(s):  
Neutralization Assay ◽  
Antibody Neutralization

scholarly journals SARS-CoV-2 Antibody Neutralization Assay Platforms Based on Epitopes Sources: Live Virus, Pseudovirus, and Recombinant S Glycoprotein RBD

2021 ◽  
Vol 21 (6) ◽  
Author(s):  
Endah Puji Septisetyani ◽  
Pekik Wiji Prasetyaningrum ◽  
Khairul Anam ◽  
Adi Santoso
Keyword(s):  
Neutralization Assay ◽  
Antibody Neutralization ◽  
Live Virus

A Hexagonal (II) Phase Phospholipid Neutralization Assay for Lupus Anticoagulant Identification

1993 ◽  
Vol 70 (05) ◽  
pp. 787-793 ◽  
Author(s):  
Douglas A Triplett ◽  
Linda K Barna ◽  
Gail A Unger
Keyword(s):  
Hemophilia A ◽  
Clinical Laboratory ◽  
Neutralization Assay ◽  
Confirmatory Test ◽  
Specific Factor ◽  
Clinical Settings ◽  
Drug Induced ◽  
Variable Screening ◽  
Routine Clinical Laboratory

SummaryLupus anticoagulants (LAs) are immunoglobulins (IgG, IgM, or both) which interfere with in vitro phospholipid (PL) dependent tests of coagulation (e.g. APTT, dilute PT, dilute Russell Viper Venom Time). These antibodies may be identified in a wide variety of clinical settings. With the exception of heparinized patient samples, the presence of LAs is often the most common cause of an unexplained APTT in a routine clinical laboratory. The diagnosis of LAs is difficult due to variable screening reagent sensitivity and intrinsic heterogeneity of LAs. Recently, Rauch and colleagues have shown human monoclonal hybridoma LAs were inhibited by hexagonal (II) phase PLs. In contrast, lamellar phase PLs had no effect. We have evaluated a new assay system, Staclot LA®, which utilizes a hexagonal (II) phase PL (egg phosphatidylethanolamine [EPE]) as a confirmatory test for LAs. Plasma samples from the following patient populations were studied: LA positive, heparinized, oral anticoagulated, hemophilia A and B, and specific factor inhibitors (factors V, VIII, IX). Unlike previous studies, the LA positive patients were a mixed population including: autoimmune diseases, drug-induced, and post-infection. Our findings confirm the specificity of hexagonal (II) phase PL neutralization of LAs.

Antimyotoxic Activity of Synthetic Peptides Derived from Bothrops atrox Snake Gamma Phospholipase A2 Inhibitor Selected by Virtual Screening

2019 ◽  
Vol 19 (22) ◽  
pp. 1952-1961 ◽  
Author(s):  
J.C. Sobrinho ◽  
A.F. Francisco ◽  
R. Simões-Silva ◽  
A.M. Kayano ◽  
J.J. Alfonso Ruiz Diaz ◽  
...  
Keyword(s):  
Amino Acids ◽  
Molecular Docking ◽  
Synthetic Peptides ◽  
Cell Damage ◽  
Neutralization Assay ◽  
Phospholipase Activity ◽  
Phospholipases A2 ◽  
Catalytically Active ◽  
Bothrops Atrox

Background: Several studies have aimed to identify molecules that inhibit the toxic actions of snake venom phospholipases A2 (PLA2s). Studies carried out with PLA2 inhibitors (PLIs) have been shown to be efficient in this assignment. Objective: This work aimed to analyze the interaction of peptides derived from Bothrops atrox PLIγ (atPLIγ) with a PLA2 and to evaluate the ability of these peptides to reduce phospholipase and myotoxic activities. Methods: Peptides were subjected to molecular docking with a homologous Lys49 PLA2 from B. atrox venom modeled by homology. Phospholipase activity neutralization assay was performed with BthTX-II and different ratios of the peptides. A catalytically active and an inactive PLA2 were purified from the B. atrox venom and used together in the in vitro myotoxic activity neutralization experiments with the peptides. Results: The peptides interacted with amino acids near the PLA2 hydrophobic channel and the loop that would be bound to calcium in Asp49 PLA2. They were able to reduce phospholipase activity and peptides DFCHNV and ATHEE reached the highest reduction levels, being these two peptides the best that also interacted in the in silico experiments. The peptides reduced the myotubes cell damage with a highlight for the DFCHNV peptide, which reduced by about 65%. It has been suggested that myotoxic activity reduction is related to the sites occupied in the PLA2 structure, which could corroborate the results observed in molecular docking. Conclusion: This study should contribute to the investigation of the potential of PLIs to inhibit the toxic effects of PLA2s.

scholarly journals Evaluation of a Pseudovirus Neutralization Assay for SARS-CoV-2 and Correlation with Live Virus-Based Micro Neutralization Assay

Diagnostics ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 994
Author(s):  
Ahmed Majdi K. Tolah ◽  
Sayed S. Sohrab ◽  
Khaled Majdi K. Tolah ◽  
Ahmed M. Hassan ◽  
Sherif A. El-Kafrawy ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Epidemiological Studies ◽  
Neutralization Assay ◽  
Serum Samples ◽  
Live Virus ◽  
Spike Gene ◽  
Microneutralization Assay ◽  
Viral Particles ◽  
Reliable Performance ◽  
Prior Infection

The unusual cases of pneumonia outbreak were reported from Wuhan city in late December 2019. Serological testing provides a powerful tool for the identification of prior infection and for epidemiological studies. Pseudotype virus neutralization assays are widely used for many viruses and applications in the fields of serology. The accuracy of pseudotype neutralizing assay allows for its use in low biosafety lab and provides a safe and effective alternative to the use of wild-type viruses. In this study, we evaluated the performance of this assay compared to the standard microneutralization assay as a reference. The lentiviral pseudotype particles were generated harboring the Spike gene of SARS-CoV-2. The generated pseudotype particles assay was used to evaluate the activity of neutralizing antibodies in 300 human serum samples from a COVID-19 sero-epidemiological study. Testing of these samples resulted in 55 positive samples and 245 negative samples by pseudotype viral particles assay while microneutralization assay resulted in 64 positive and 236 negative by MN assay. Compared to the MN, the pseudotyped viral particles assay showed a sensitivity of 85.94% and a specificity of 100%. Based on the data generated from this study, the pseudotype-based neutralization assay showed a reliable performance for the detection of neutralizing antibodies against SARS-CoV-2 and can be used safely and efficiently as a diagnostic tool in a biosafety level 2 laboratory.

scholarly journals Association Between Federal Value-Based Incentive Program Implementation and Hospital-Onset C. difficile Infection Rates

2020 ◽  
Vol 41 (S1) ◽  
pp. s133-s133
Author(s):  
Mohammad Alrawashdeh ◽  
Chanu Rhee ◽  
Heather Hsu ◽  
Grace Lee
Keyword(s):  
Program Implementation ◽  
Negative Binomial ◽  
Negative Binomial Regression ◽  
Neutralization Assay ◽  
Nucleic Acid Amplification ◽  
Teaching Hospitals ◽  
Future Research ◽  
Testing Methods ◽  
Toxigenic Culture ◽  
The Impact

Background: The Hospital-Acquired Conditions Reduction Program (HACRP) and Hospital Value-Based Purchasing (HVBP) are federal value-based incentive programs that financially reward or penalize hospitals based on quality metrics. Hospital-onset C. difficile infection (HO-CDI) rates reported to the CDC NHSN became a target quality metric for both HACRP and HVBP in October 2016, but the impact of these programs on HO-CDI rates is unknown. Methods: We used an interrupted time-series design to examine the association between HACRP/HVBP implementation in October 2016 and quarterly rates of HO-CDI per 10,000 patient days among incentive-eligible acute-care hospitals conducting facility-wide HO-CDI NHSN surveillance between January 2013 and March 2019. Generalized estimating equations were used to fit negative binomial regression models to assess for immediate program impact (ie, level change) and changes in the slope of HO-CDI rates, controlling for each hospital’s predominant method for CDI testing (nucleic acid amplification including PCR (NAAT), enzyme immunoassay for toxin (EIA), or other testing method including cell cytotoxicity neutralization assay and toxigenic culture). Results: Of the 265 study hospitals studied, most were medium-sized (100–399 beds, 55%), not-for-profit (77%), teaching hospitals (70%), and were located in a metropolitan area (87%). Compared to EIA, rates of HO-CDI were higher when detected by NAAT (incidence rate ratio [IRR], 1.55; 95% CI, 1.41–1.70) or other testing methods (IRR, 1.47; 95% CI, 1.26–1.71). Controlling for CDI testing methods, HACRP/HVBP implementation was associated with an immediate 6% decline in HO-CDI rates (IRR, 0.94; 95% CI, 0.89–0.99) and a 4% decline in slope per year-quarter thereafter (IRR, 0.96; 95% CI, 0.95–0.97) (Fig. 1). Conclusions: HACRP/HVBP implementation was associated with both immediate and gradual improvements in HO-CDI rates, independent of CDI testing methods of differing sensitivity. Future research may evaluate the precise mechanisms underlying this improvement and if this impact is sustained in the long term.Funding: NoneDisclosures: None

scholarly journals Use of a Toxin Neutralization Assay To Characterize the Serologic Response to Adenylate Cyclase Toxin after Infection with Bordetella pertussis

2016 ◽  
Vol 24 (1) ◽  
Author(s):  
Joshua C. Eby ◽  
Mary C. Gray ◽  
Jason M. Warfel ◽  
Tod J. Merkel ◽  
Erik L. Hewlett
Keyword(s):  
Adenylate Cyclase ◽  
Bordetella Pertussis ◽  
Neutralization Assay ◽  
Enzyme Linked Immunosorbent Assay ◽  
Immunologic Response ◽  
Serum Samples ◽  
Content Type ◽  
Adenylate Cyclase Toxin ◽  
Strong Candidate ◽  
Candidate Antigen

ABSTRACT Adenylate cyclase toxin (ACT) is an essential virulence factor of Bordetella pertussis, and antibodies to ACT protect against B. pertussis infection in mice. The toxin is therefore a strong candidate antigen for addition to future acellular pertussis vaccines. In order to characterize the functionality of the immunologic response to ACT after infection, we developed an assay for testing the ability of serum samples from subjects infected with B. pertussis to neutralize ACT-induced cytotoxicity in J774 macrophage cells. Baboons develop neutralizing anti-ACT antibodies following infection with B. pertussis, and all sera from baboons with positive anti-ACT IgG enzyme-linked immunosorbent assay (ELISA) results neutralized ACT cytotoxicity. The toxin neutralization assay (TNA) was positive in some baboon sera in which ELISA remained negative. Of serum samples obtained from humans diagnosed with pertussis by PCR, anti-ACT IgG ELISA was positive in 72%, and TNA was positive in 83%. All samples positive for anti-ACT IgG ELISA were positive by TNA, and none of the samples from humans without pertussis neutralized toxin activity. These findings indicate that antibodies to ACT generated following infection with B. pertussis consistently neutralize toxin-induced cytotoxicity and that TNA can be used to improve understanding of the immunologic response to ACT after infection or vaccination.

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