scholarly journals Development of a flow cytometric bead immunoassay and its assessment as a possible aid to potency evaluation of enterotoxaemia vaccines

2014 ◽  
Vol 85 (1) ◽  
Author(s):  
Angela Buys ◽  
Raynard Macdonald ◽  
Jannie Crafford ◽  
Jacques Theron
Keyword(s):  
Cost Effective ◽  
In Vitro Assays ◽  
Enzyme Linked Immunosorbent Assay ◽  
In Vitro Tests ◽  
Serum Samples ◽  
Type D ◽  
Epsilon Toxin ◽  
Bead Immunoassay

Enterotoxaemia, an economically important disease of sheep, goats and calves, is caused by systemic effects of the epsilon toxin produced by the anaerobic bacterium Clostridium perfringens type D. The only practical means of controlling the occurrence of enterotoxaemia is to immunise animals by vaccination. The vaccine is prepared by deriving a toxoid from the bacterial culture filtrate and the potency of the vaccine is tested with the in vivo mouse neutralisation test (MNT). Due to ethical, economic and technical reasons, alternative in vitro assays are needed. In this study an indirect cytometric bead immunoassay (I-CBA) was developed for use in vaccine potency testing and the results were compared with those obtained using an indirect enzyme-linked immunosorbent assay (I-ELISA) and the MNT. Sera were collected from guinea pigs immunised with three different production batches of enterotoxaemia vaccine and the levels of anti-epsilon toxin antibodies were determined. Although the intra- and inter-assay variability was satisfactory, epsilon antitoxin levels determined by both the I-ELISA and indirect cytometric bead immunoassay (I-CBA) tests were higher than those of the MNT assay. In contrast to the MNT, all of the serum samples were identified as having antitoxin levels above the required minimum (not less than 5 U/mL). These results indicate that the respective in vitro tests in their current formats are not yet suitable alternatives to the in vivo MNT. The growing demand for a more humane, cost-effective and efficient method for testing the potency of enterotoxaemia vaccines, however, provides a strong impetus for further optimisation and standardisation of the I-CBA assay but further analytical research is required.

scholarly journals The Versatility of Antioxidant Assays in Food Science and Safety—Chemistry, Applications, Strengths, and Limitations

Antioxidants ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 709 ◽  
Author(s):  
Nabeelah Bibi Sadeer ◽  
Domenico Montesano ◽  
Stefania Albrizio ◽  
Gokhan Zengin ◽  
Mohamad Fawzi Mahomoodally
Keyword(s):  
Cost Effective ◽  
Food Samples ◽  
Chemical Mechanism ◽  
In Vitro Assays ◽  
Poor Correlation ◽  
Antioxidant Assays ◽  
Antioxidant Capacities ◽  
Effective Assessment

Currently, there is a growing interest in screening and quantifying antioxidants from biological samples in the quest for natural and effective antioxidants to combat free radical-related pathological complications. Antioxidant assays play a crucial role in high-throughput and cost-effective assessment of antioxidant capacities of natural products such as medicinal plants and food samples. However, several investigators have expressed concerns about the reliability of existing in vitro assays. Such concerns arise mainly from the poor correlation between in vitro and in vivo results. In addition, in vitro assays have the problem of reproducibility. To date, antioxidant capacities are measured using a panel of assays whereby each assay has its own advantages and limitations. This unparalleled review hotly disputes on in vitro antioxidant assays and elaborates on the chemistry behind each assay with the aim to point out respective principles/concepts. The following critical questions are also addressed: (1) What make antioxidant assays coloured? (2) What is the reason for working at a particular wavelength? (3) What are the advantages and limitations of each assay? and (4) Why is a particular colour observed in antioxidant–oxidant chemical reactions? Furthermore, this review details the chemical mechanism of reactions that occur in each assay together with a colour ribbon to illustrate changes in colour. The review ends with a critical conclusion on existing assays and suggests constructive improvements on how to develop an adequate and universal antioxidant assay.

In Vitro Toxicology and the Test Guidelines

1996 ◽  
Vol 24 (3) ◽  
pp. 435-438
Author(s):  
Kimmo Louekari
Keyword(s):  
Cost Effective ◽  
Test Methods ◽  
In Vitro Tests ◽  
In Vitro Test ◽  
In Vitro Methods ◽  
Effective Manner ◽  
Genotoxic Carcinogens ◽  
Vitro Test

Ethical, economical and scientific considerations should encourage the development of alternative and in vitro test methods. Before their adoption, in vitro methods need to be validated and scientifically justified. Demand for rigorous validation schemes for in vitro tests must be emphasised, even more than in the case of in vivo tests. The OECD has adopted in vitro guidelines for testing genotoxicity; several endpoints and mechanisms can be studied in a cost-effective manner in vitro. Similar advantages could be afforded if acute irritation and corrosion, as well as the non-genotoxic carcinogenic effects of chemicals, could be studied in vitro. Evaluation of the validation status of various methods used to study non-genotoxic carcinogens was begun by the Nordic Working Group on In Vitro Methods for Non-genotoxic Mechanisms in 1996. In some established OECD test guidelines (for example, the dermal irritation/corrosion test), there is already room for the application of in vitro methods which have not been formally validated. In January 1996, the OECD Workshop on Harmonisation of Validation and Acceptance Criteria for Alternative Toxicological Test Methods set the basis for internationally acceptable principles to be followed in the validation of in vitro test methods.

Regulatory Perspective on in Vitro Assays as Predictors of Phototoxicity and Photo Co-Carcinogenicity

1998 ◽  
Vol 17 (5) ◽  
pp. 571-575 ◽  
Author(s):  
Amy L. Ellis
Keyword(s):  
Mammalian Cells ◽  
Hairless Mouse ◽  
In Vitro Assays ◽  
In Vitro Tests ◽  
Drug Products ◽  
Drug Classes ◽  
Wide Range ◽  
Regulatory Perspective

Drugs from a variety of chemical classes used for a wide range of therapeutic indications can be photosensitizers in humans. Several drugs are phototoxic in animal models as well; there are no nonclinical data for many. In vitro tests have been developed as predictors of phototoxicity and although they have been used as screens, none have replaced the in vivo tests done in rodents (usually mice or guinea pigs) since these have been good predictors of clinical phototoxicity. Some phototoxic drug classes are co-carcinogens with ultraviolet radiation (UVA and/or UVB) in hairless mice, specifically psoralens, retinoids, and fluo-roquinolones. Treatment with 8-methoxypsoralen and ultraviolet A radiation for psoriasis is also carcinogenic in humans. It has been suggested that in vitro photogenotoxicity assays using microorganisms or mammalian cells may be predictive of photo co-carcinogenicity. Some attractions of these in vitro assays, compared to the hairless mouse photo co-carcinogenicity assay, are their generally shorter duration and lower cost as well as reducing the number of animals used in research. Currently, personnel at the Food and Drug Administration (FDA) are examining the available data on phototoxicity, photogenotoxicity, and photo co-carcinogenicity to determine how this information can best be used toregulate and label drug products, and considering which assays should be recommended under specific circumstances.

scholarly journals Foxp3 Silencing with Antisense Oligonucleotide Improves Immunogenicity of an Adjuvanted Recombinant Vaccine against Sporothrix schenckii

2021 ◽  
Vol 22 (7) ◽  
pp. 3470
Author(s):  
Alexander Batista-Duharte ◽  
Luis Sendra ◽  
Maria José Herrero ◽  
Deivys Leandro Portuondo ◽  
Damiana Téllez-Martínez ◽  
...  
Keyword(s):  
Immune Responses ◽  
Sporothrix Schenckii ◽  
Recombinant Vaccine ◽  
Enzyme Linked Immunosorbent Assay ◽  
Serum Samples ◽  
Murine Splenocytes ◽  
Treg Depletion ◽  
In Vivo Experiments

Background: In recent years, there has been great interest in developing molecular adjuvants based on antisense oligonucleotides (ASOs) targeting immunosuppressor pathways with inhibitory effects on regulatory T cells (Tregs) to improve immunogenicity and vaccine efficacy. We aim to evaluate the immunostimulating effect of 2′OMe phosphorothioated Foxp3-targeted ASO in an antifungal adjuvanted recombinant vaccine. Methods: The uptake kinetics of Foxp3 ASO, its cytotoxicity and its ability to deplete Tregs were evaluated in murine splenocytes in vitro. Groups of mice were vaccinated with recombinant enolase (Eno) of Sporothix schenckii in Montanide Gel 01 adjuvant alone or in combination with either 1 µg or 8 µg of Foxp3 ASO. The titers of antigen-specific antibody in serum samples from vaccinated mice (male C57BL/6) were determined by ELISA (enzyme-linked immunosorbent assay). Cultured splenocytes from each group were activated in vitro with Eno and the levels of IFN-γ and IL-12 were also measured by ELISA. The results showed that the anti-Eno antibody titer was significantly higher upon addition of 8 µM Foxp3 ASO in the vaccine formulation compared to the standard vaccine without ASO. In vitro and in vivo experiments suggest that Foxp3 ASO enhances specific immune responses by means of Treg depletion during vaccination. Conclusion: Foxp3 ASO significantly enhances immune responses against co-delivered adjuvanted recombinant Eno vaccine and it has the potential to improve vaccine immunogenicity.

scholarly journals Evaluation of Leishmania infantum 30x biotherapy effects in the prevention and treatment of visceral leishmaniasis: in vivo and in vitro studies

2021 ◽  
Vol 15 (4) ◽  
pp. 26-29
Author(s):  
Ana Paula Bacellar Cajueiro ◽  
Gleyce Moreno Barbosa ◽  
Fortune Homsani ◽  
Ana Paula dos Santos Matos ◽  
Igor Almeida Rodrigues ◽  
...  
Keyword(s):  
Leishmania Infantum ◽  
Therapeutic Potential ◽  
Public Health Problem ◽  
In Vivo Studies ◽  
In Vitro Assays ◽  
Serum Samples ◽  
Hydropic Degeneration ◽  
No Release

Background: Leishmaniasis is a serious public health problem especially in developing countries [1]. The therapeutic potential of biotherapics against several microorganism has been described in vitro [2,3] and in vivo studies [4,5,6,7,8,9]. Considering the resistance of leishmaniasis to conventional treatment as well as previous studies with biotherapic, we evaluated the effects of Leishmania infantum 30x (BioLi30x) biotherapy. Aim: evaluate the antileishmanial effects of BioLi30x in in vivo and in vitro models. Methodology: The in vivo experiments were performed using BALB/c mice (n=138), divided into 8 groups: G1-healthy, G2-infected with L. infantum, G3-BioLi30x pre-treated, G4-BioLi30x pre/post-treated, G5-BioLi30x post-treated, G6-H2O30x post-treated, G7-Antimonium crudum 30x post-treated and G8-Glucantime® post-treated. After 49 days of treatment, the animals were submitted to euthanasia (ethical approval ECUA/UFRJ/066/14). Liver and spleen histological changes were evaluated, and serum samples were aliquoted and storage at -20°C for cytokine assays. The in vitro assays were performed using RAW 264.7 macrophages treated with BioLi30x and infected with L. infantum. The morphological aspects were evaluated by scanning electron microscopy (SEM), and the nitric oxide (NO) release was quantified in the supernatant of infected macrophages. Results: The histological analysis from 4 independent experiments showed livers with normal appearance (G1); periportal chronic hepatitis (G2,G4,G5,G8); discreet (G3,G7), moderate (G4,G5,G6), and severe (G2,G8) vacuolar hydropic degeneration; congestion and neutrophilic inflammation (G2,G4,G5,G6,G8), and possible amastigotes within macrophages (G2-G8). Spleens presented healthy appearance only in G1. All treated animals presented histological alterations, with different lesions severity, which involved spleen pulp hyperplasia with moderate disruption (G2,G8), as well as megakaryocytes and macrophages proliferation (G2- G8). SEM analyses showed BioLi30x treatments induced significant protozoan morphology alterations when compared to H2O30x. Besides, a 19% increase in the NO release was detected in RAW supernatants, when compared to H2O30x. Conclusions: BioLi30x and Antimonium crudum 30x modified the infection animal process, involving several cellular mechanisms as well as different histological damage. The in vitro experiments will be repeated in order to confirm these preliminary results.

scholarly journals In vitro potency test for evaluation of Clostridium perfringens type D epsilon toxoid

2013 ◽  
Vol 80 (4) ◽  
pp. 450-452 ◽  
Author(s):  
Felipe Masiero Salvarini ◽  
Zelia Ines Portela Lobato ◽  
Prhiscylla Sadana Pires ◽  
Rodrigo Otavio Silveira Silva ◽  
Guilherme Guerra Alves ◽  
...  
Keyword(s):  
Clostridium Perfringens ◽  
Neutralizing Antibodies ◽  
Mdck Cells ◽  
In Vitro Test ◽  
Type D ◽  
Epsilon Toxin ◽  
Vitro Test ◽  
Darby Canine Kidney

The control of enterotoxemia caused by the epsilon toxin, produced by Clostridium perfringens type D, is based on vaccination with epsilon toxoid. The potency test for this immunogen is conducted using seroneutralization in mice. Here, an in vitro test for detection of neutralizing antibodies with Madin-Darby Canine Kidney (MDCK) cells was standardized in order to study alternative methodologies for the potency test. Titers observed in the in vivo and in vitro seroneutralization tests had a correlation of 99.73%.

scholarly journals Identification of Campylobacter jejuni Proteins Recognized by Maternal Antibodies of Chickens

2008 ◽  
Vol 74 (22) ◽  
pp. 6867-6875 ◽  
Author(s):  
Kari D. Shoaf-Sweeney ◽  
Charles L. Larson ◽  
Xiaoting Tang ◽  
Michael E. Konkel
Keyword(s):  
Campylobacter Jejuni ◽  
Immunoblot Analysis ◽  
Protective Role ◽  
Maternal Antibodies ◽  
In Vitro Assays ◽  
Enzyme Linked Immunosorbent Assay ◽  
Serum Samples ◽  
Homologous Strain ◽  
Protective Antibodies

ABSTRACT Campylobacter jejuni is one of the leading bacterial causes of food-borne gastroenteritis. Infection with C. jejuni is frequently acquired through the consumption of undercooked poultry or foods cross-contaminated with raw poultry. Given the importance of poultry as a reservoir for Campylobacter organisms, investigators have performed studies to understand the protective role of maternal antibodies in the ecology of Campylobacter colonization of poultry. In a previous study, chicks with maternal antibodies generated against the S3B strain of C. jejuni provided protection against Campylobacter colonization (O. Sahin, N. Luo, S. Huang, and Q. Zhang, Appl. Environ. Microbiol. 69:5372-5379, 2003). We obtained serum samples, collectively referred to as the C. jejuni S3B-SPF sera, from the previous study. These sera were determined to contain maternal antibodies that reacted against C. jejuni whole-cell lysates as judged by enzyme-linked immunosorbent assay. The antigens recognized by the C. jejuni S3B-SPF antibodies were identified by immunoblot analysis, coupled with mass spectrometry, of C. jejuni outer membrane protein extracts. This approach led to the identification of C. jejuni proteins recognized by the maternal antibodies, including the flagellin proteins and CadF adhesin. In vitro assays revealed that the C. jejuni S3B-SPF sera retarded the motility of the C. jejuni S3B homologous strain but did not retard the motility of a heterologous strain of C. jejuni (81-176). This finding provides a possible mechanism explaining why maternal antibodies confer enhanced protection against challenge with a homologous strain compared to a heterologous strain. Collectively, this study provides a list of C. jejuni proteins against which protective antibodies are generated in hens and passed to chicks.

scholarly journals Assessment of Three In Vitro Tests and an In Vivo Test for Chloroquine Resistance in Plasmodium falciparumClinical Isolates

1998 ◽  
Vol 36 (1) ◽  
pp. 243-247 ◽  
Author(s):  
Jean Bickii ◽  
Leonardo K. Basco ◽  
Pascal Ringwald
Keyword(s):  
Host Factors ◽  
Chloroquine Resistance ◽  
In Vitro Assays ◽  
In Vitro Tests ◽  
In Vitro Test ◽  
In Vivo Evaluation ◽  
In Vivo Test ◽  
Vitro Test

Three in vitro assays (the isotopic semimicrotest [700 μl per well; 24-well plates], the isotopic microtest [200 μl per well; 96-well plates], and the rapid in vitro test) and the standard in vivo test for chloroquine resistance were compared for 99 clinical isolates of Plasmodium falciparum obtained from symptomatic African patients. The 50% inhibitory concentrations determined by the two isotopic tests were similar and were highly correlated (r = 0.965; P < 0.05), showing a high concordance between the semimicrotest and the microtest. There was a moderate agreement between these two isotopic tests and the in vivo test. Most of the discordant results were probably due to host factors, including reinfections, pharmacokinetic variations, and immunologic response, which are eliminated in in vitro assays. The rapid in vitro test based on the inhibition of chloroquine efflux in the presence of verapamil was poorly concordant with the other tests. Despite some discordant results, isotopic in vitro assays are useful to characterize the phenotypes of individual isolates without the interference of host factors and are complementary to in vivo evaluation of drug efficacy. However, in vitro assays need to be standardized to allow direct comparison of results between different laboratories.

A in Vivo Assay for Standardizing Heparin Preparations

1979 ◽  
Vol 41 (03) ◽  
pp. 576-582
Author(s):  
A R Pomeroy
Keyword(s):  
In Vitro Assays ◽  
British Pharmacopoeia ◽  
In Vitro Method ◽  
Standard Preparation ◽  
Reliable Estimation ◽  
Assay Procedure ◽  
Accuracy And Precision ◽  
Heparin Preparation

SummaryThe limitations of currently used in vitro assays of heparin have demonstrated the need for an in vivo method suitable for routine use.The in vivo method which is described in this paper uses, for each heparin preparation, four groups of five mice which are injected intravenously with heparin according to a “2 and 2 dose assay” procedure. The method is relatively rapid, requiring 3 to 4 hours to test five heparin preparations against a standard preparation of heparin. Levels of accuracy and precision acceptable for the requirements of the British Pharmacopoeia are obtained by combining the results of 3 to 4 assays of a heparin preparation.The similarity of results obtained the in vivo method and the in vitro method of the British Pharmacopoeia for heparin preparations of lung and mucosal origin validates this in vivo method and, conversely, demonstrates that the in vitro method of the British Pharmacopoeia gives a reliable estimation of the in vivo activity of heparin.

Potentially Thrombogenic Materials in Factor IX Concentrates

1975 ◽  
Vol 33 (03) ◽  
pp. 617-631 ◽  
Author(s):  
H. S Kingdon ◽  
R. L Lundblad ◽  
J. J Veltkamp ◽  
D. L Aronson
Keyword(s):  
Human Plasma ◽  
Antithrombin Iii ◽  
Factor Ix ◽  
In Vitro Assays ◽  
Substantial Agreement ◽  
Coefficient Of Correlation

SummaryFactor IX concentrates manufactured from human plasma and intended for therapeutic infusion in man have been suspected for some time of being potentially thrombogenic. In the current studies, assays were carried out in vitro and in vivo for potentially thrombogenic materials. It was possible to rank the various materials tested according to the amount of thrombogenic material detected. For concentrates not containing heparin, there was substantial agreement between the in vivo and in vitro assays, with a coefficient of correlation of 0.77. There was no correlation between the assays for thrombogenicity and the antithrombin III content. We conclude that many presently available concentrates of Factor IX contain substantial amounts of potentially thrombogenic enzymes, and that this fact must be considered in arriving at the decision whether or not to use them therapeutically.

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