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Opsteegh M, Cuperus T, van Buuren C, Dam-Deisz C, van Solt-Smits C, Verhaegen B, Joeres M, Schares G, Koudela B, Egberts F, Verkleij T, van der Giessen J, Wisselink HJ. In vitro assay to determine inactivation of Toxoplasma gondii in meat samples. Int J Food Microbiol 2024; 416:110643. [PMID: 38452660 DOI: 10.1016/j.ijfoodmicro.2024.110643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 02/12/2024] [Accepted: 02/24/2024] [Indexed: 03/09/2024]
Abstract
Consumption of raw and undercooked meat is considered as an important source of Toxoplasma gondii infections. However, most non-heated meat products contain salt and additives, which affect T. gondii viability. It was our aim to develop an in vitro method to substitute the mouse bioassay for determining the effect of salting on T. gondii viability. Two sheep were experimentally infected by oral inoculation with 6.5 × 104 oocysts. Grinded meat samples of 50 g were prepared from heart, diaphragm, and four meat cuts. Also, pooled meat samples were either kept untreated (positive control), frozen (negative control) or supplemented with 0.6 %, 0.9 %, 1.2 % or 2.7 % NaCl. All samples were digested in pepsin-HCl solution, and digests were inoculated in duplicate onto monolayers of RK13 (a rabbit kidney cell line). Cells were maintained for up to four weeks and parasite growth was monitored by assessing Cq-values using the T. gondii qPCR on cell culture supernatant in intervals of one week and ΔCq-values determined. Additionally, 500 μL of each digest from the individual meat cuts, heart and diaphragm were inoculated in duplicate in IFNγ KO mice. Both sheep developed an antibody response and tissue samples contained similar concentrations of T. gondii DNA. From all untreated meat samples positive ΔCq-values were obtained in the in vitro assay, indicating presence and multiplication of viable parasites. This was in line with the mouse bioassay, with the exception of a negative mouse bioassay on one heart sample. Samples supplemented with 0.6 %-1.2 % NaCl showed positive ΔCq-values over time. The frozen sample and the sample supplemented with 2.7 % NaCl remained qPCR positive but with high Cq-values, which indicated no growth. In conclusion, the in vitro method has successfully been used to detect viable T. gondii in tissues of experimentally infected sheep, and a clear difference in T. gondii viability was observed between the samples supplemented with 2.7 % NaCl and those with 1.2 % NaCl or less.
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Affiliation(s)
- Marieke Opsteegh
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven, the Netherlands.
| | - Tryntsje Cuperus
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven, the Netherlands.
| | - Chesley van Buuren
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven, the Netherlands.
| | - Cecile Dam-Deisz
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven, the Netherlands.
| | - Conny van Solt-Smits
- Wageningen Bioveterinary Research, Wageningen University and Research, P.O. Box 65, 8200 AB Lelystad, the Netherlands.
| | - Bavo Verhaegen
- Sciensano, Service of Foodborne Pathogens, Rue Juliette Wytsmanstraat 14, 1050 Brussels, Belgium.
| | - Maike Joeres
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Epidemiology, National Reference Centre for Toxoplasmosis, Südufer 10, 17493 Greifswald-Insel Riems, Germany
| | - Gereon Schares
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Epidemiology, National Reference Centre for Toxoplasmosis, Südufer 10, 17493 Greifswald-Insel Riems, Germany.
| | - Břetislav Koudela
- Department of Pathology and Parasitology, Faculty of Veterinary Medicine, University of Veterinary Sciences Brno, Palackého tř. 1946/1, 61242 Brno, Czech Republic.
| | - Frans Egberts
- Dutch Meat Products Association (VNV), P.O. Box 61, 2700 AB Zoetermeer, the Netherlands.
| | - Theo Verkleij
- Wageningen Food & Biobased Research, P.O. Box 17, 6700 AA Wageningen, the Netherlands.
| | - Joke van der Giessen
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven, the Netherlands.
| | - Henk J Wisselink
- Wageningen Bioveterinary Research, Wageningen University and Research, P.O. Box 65, 8200 AB Lelystad, the Netherlands.
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Fabian BT, Hedar F, Koethe M, Bangoura B, Maksimov P, Conraths FJ, Villena I, Aubert D, Seeber F, Schares G. Fluorescent bead-based serological detection of Toxoplasma gondii infection in chickens. Parasit Vectors 2020; 13:388. [PMID: 32736581 PMCID: PMC7393333 DOI: 10.1186/s13071-020-04244-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 07/20/2020] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Free-ranging chickens are often infected with Toxoplasma gondii and seroconvert upon infection. This indicates environmental contamination with T. gondii. METHODS Here, we established a bead-based multiplex assay (BBMA) using the Luminex technology for the detection of T. gondii infections in chickens. Recombinant biotinylated T. gondii surface antigen 1 (TgSAG1bio) bound to streptavidin-conjugated magnetic Luminex beads served as antigen. Serum antibodies were detected by a fluorophore-coupled secondary antibody. Beads of differing color codes were conjugated with anti-chicken IgY or chicken serum albumin and served for each sample as an internal positive or negative control, respectively. The assay was validated with sera from experimentally and naturally infected chickens. The results were compared to those from reference methods, including other serological tests, PCRs and bioassay in mice. RESULTS In experimentally infected chickens, the vast majority (98.5%, n = 65/66) of birds tested seropositive in the BBMA. This included all chickens positive by magnetic-capture PCR (100%, n = 45/45). Most, but not all inoculated and TgSAG1bio-BBMA-positive chickens were also positive in two previously established TgSAG1-ELISAs (TgSAG1-ELISASL, n = 61/65; or TgSAG1-ELISASH, n = 60/65), or positive in an immunofluorescence assay (IFAT, n = 64/65) and in a modified agglutination test (MAT, n = 61/65). All non-inoculated control animals (n = 28/28, 100%) tested negative. In naturally exposed chickens, the TgSAG1bio-BBMA showed a high sensitivity (98.5%; 95% confidence interval, CI: 90.7-99.9%) and specificity (100%; 95% CI: 85.0-100%) relative to a reference standard established using ELISA, IFAT and MAT. Almost all naturally exposed chickens that were positive in bioassay or by PCR tested positive in the TgSAG1bio-BBMA (93.5%; 95% CI: 77.1-98.9%), while all bioassay- or PCR-negative chickens remained negative (100%; 95% CI: 85.0-100%). CONCLUSIONS The TgSAG1bio-BBMA represents a suitable method for the detection of T. gondii infections in chickens with high sensitivity and specificity, which is comparable or even superior to other tests. Since assays based on this methodology allow for the simultaneous analysis of a single biological sample with respect to multiple analytes, the described assay may represent a component in future multiplex assays for broad serological monitoring of poultry and other farm animals for various pathogens.
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Affiliation(s)
- Benedikt T. Fabian
- FG16: Mycotic and Parasitic Agents and Mycobacteria, Robert Koch-Institute, Berlin, Germany
| | - Fatima Hedar
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Epidemiology, National Reference Centre for Toxoplasmosis, Greifswald-Insel Riems, Germany
| | - Martin Koethe
- Faculty of Veterinary Medicine, Institute of Food Hygiene, Leipzig University, Leipzig, Germany
| | - Berit Bangoura
- Faculty of Veterinary Medicine, Institute of Parasitology, Leipzig University, Leipzig, Germany
- Department of Veterinary Sciences, Wyoming State Veterinary Laboratory, University of Wyoming, Laramie, USA
| | - Pavlo Maksimov
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Epidemiology, National Reference Centre for Toxoplasmosis, Greifswald-Insel Riems, Germany
| | - Franz J. Conraths
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Epidemiology, National Reference Centre for Toxoplasmosis, Greifswald-Insel Riems, Germany
| | - Isabelle Villena
- EA 7510, UFR Medecine, University of Reims Champagne Ardenne, Reims, France
- Laboratory of Parasitology, National Reference Centre on Toxoplasmosis, Centre Hospitalier Universitaire de Reims, Reims, France
| | - Dominique Aubert
- EA 7510, UFR Medecine, University of Reims Champagne Ardenne, Reims, France
- Laboratory of Parasitology, National Reference Centre on Toxoplasmosis, Centre Hospitalier Universitaire de Reims, Reims, France
| | - Frank Seeber
- FG16: Mycotic and Parasitic Agents and Mycobacteria, Robert Koch-Institute, Berlin, Germany
| | - Gereon Schares
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Epidemiology, National Reference Centre for Toxoplasmosis, Greifswald-Insel Riems, Germany
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Epidemiologic significance of Toxoplasma gondii infections in chickens ( Gallus domesticus): the past decade. Parasitology 2020; 147:1263-1289. [PMID: 32660653 DOI: 10.1017/s0031182020001134] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Toxoplasma gondii infections are common in humans and animals worldwide. Domestic free-range chickens (Gallus domesticus) are excellent sentinels of environmental contamination with T. gondii oocysts because they feed on the ground. Chickens can be easily infected with T. gondii; however, clinical toxoplasmosis is rare in these hosts. Chickens are comparatively inexpensive and thus are good sentinel animals for T. gondii infections on the farms. Here, the authors reviewed prevalence, the persistence of infection, clinical disease, epidemiology and genetic diversity of T. gondii strains isolated from chickens worldwide for the past decade. Data on phenotypic and molecular characteristics of 794 viable T. gondii strains from chickens are discussed, including new data on T. gondii isolates from chickens in Brazil. This paper will be of interest to biologists, epidemiologists, veterinarians and parasitologists.
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Stelzer S, Basso W, Benavides Silván J, Ortega-Mora L, Maksimov P, Gethmann J, Conraths F, Schares G. Toxoplasma gondii infection and toxoplasmosis in farm animals: Risk factors and economic impact. Food Waterborne Parasitol 2019; 15:e00037. [PMID: 32095611 PMCID: PMC7033994 DOI: 10.1016/j.fawpar.2019.e00037] [Citation(s) in RCA: 180] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 01/25/2019] [Accepted: 01/30/2019] [Indexed: 12/23/2022] Open
Abstract
The protozoan parasite Toxoplasma gondii is a zoonotic parasite that can be transmitted from animals to humans. Felids, including domestic cats, are definitive hosts that can shed oocysts with their feces. In addition to infections that occur by accidental oral uptake of food or water contaminated with oocysts, it is assumed that a large proportion of affected humans may have become infected by consuming meat or other animal products that contained infective parasitic stages of T. gondii. Since farm animals represent a direct source of infection for humans, but also a possible reservoir for the parasite, it is important to control T. gondii infections in livestock. Moreover, T. gondii may also be pathogenic to livestock where it could be responsible for considerable economic losses in some regions and particular farming systems, e.g. in areas where the small ruminant industry is relevant. This review aims to summarize actual knowledge on the prevalence and effects of infections with T. gondii in the most important livestock species and on the effects of toxoplasmosis on livestock. It also provides an overview on potential risk factors favoring infections of livestock with T. gondii. Knowledge on potential risk factors is prerequisite to implement effective biosecurity measures on farms to prevent T. gondii infections. Risk factors identified by many studies are cat-related, but also those associated with a potential contamination of fodder or water, and with access to a potentially contaminated environment. Published information on the costs T. gondii infections cause in livestock production, is scarce. The most recent peer reviewed reports from Great Britain and Uruguay suggest annual cost of about 5-15 million US $ per country. Since these estimates are outdated, future studies are needed to estimate the present costs due to toxoplasmosis in livestock. Further, the fact that T. gondii infections in livestock may affect human health needs to be considered and the respective costs should also be estimated, but this is beyond the scope of this article.
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Affiliation(s)
- S. Stelzer
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Epidemiology, Südufer 10, 17493 Greifswald - Insel Riems, Germany
| | - W. Basso
- Institute of Parasitology, University of Bern, Länggassstrasse 122, 3012 Bern, Switzerland
| | - J. Benavides Silván
- Instituto de Ganadería de Montaña (CSIC-Universidad de León) Grulleros, 24346 León, Spain
| | - L.M. Ortega-Mora
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
| | - P. Maksimov
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Epidemiology, Südufer 10, 17493 Greifswald - Insel Riems, Germany
| | - J. Gethmann
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Epidemiology, Südufer 10, 17493 Greifswald - Insel Riems, Germany
| | - F.J. Conraths
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Epidemiology, Südufer 10, 17493 Greifswald - Insel Riems, Germany
| | - G. Schares
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Epidemiology, Südufer 10, 17493 Greifswald - Insel Riems, Germany
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Bier NS, Schares G, Johne A, Martin A, Nöckler K, Mayer-Scholl A. Performance of three molecular methods for detection of Toxoplasma gondii in pork. Food Waterborne Parasitol 2019; 14:e00038. [PMID: 32095606 PMCID: PMC7034005 DOI: 10.1016/j.fawpar.2019.e00038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 01/28/2019] [Accepted: 02/04/2019] [Indexed: 11/29/2022] Open
Abstract
Comparison of epidemiological data on the occurrence of Toxoplasma (T.) gondii tissue cysts in meat is hampered by the lack of standardization and a great variety of methods for molecular detection. Therefore, this study aimed to compare and validate three different polymerase chain reaction (PCR) methods for detection of T. gondii DNA in pork. Analytical performance characteristics of two real time PCRs (qPCRs; Tg-qPCR1, Tg-qPCR2) and one conventional endpoint PCR (cPCR), all targeting the 529 repeated element, were assessed using genomic DNA of three clonal T. gondii types prevailing in Europe and North America. qPCR efficiencies for all three clonal types ranged between 93.8 and 94.4% (Tg-qPCR1) and 94.3–95.6% (Tg-qPCR2). Tg-qPCR1 and Tg-qPCR2 showed an overall PCR performance score of 85% and displayed a similar 95% detection limit of 1.067 and 1.561 genome equivalents per PCR reaction (GE/PCR), respectively. However, T. gondii DNA could be detected at concentrations as low as 0.1 GE/PCR. Reliable quantification is possible over 4 log ranges from 105 to 100 GE/PCR with mean repeatability relative standard deviations of ≤11% and reproducibility relative standard deviations of ≤12.7%. Presumably, both qPCRs are similarly suitable for sensitive and specific detection of T. gondii DNA in pork. In contrast, the cPCR using primer pair TOX5/Tox-8 proved to be highly sensitive with a detection limit of 1.41 GE/PCR, but not suitable for detection of T. gondii DNA in pork as unspecific amplification of porcine DNA was observed resulting in bands with similar size to the desired T. gondii-specific PCR product. Comparison of two real time PCRs and one conventional PCR targeting the 529 RE. Both real time PCRs show comparable performance and can be considered equivalent. qPCRs show 95% detection limits of 1.067 and 1.561 genome equivalents per PCR. Reliable quantification is possible over 4 log ranges from 105 to 100 GE/PCR. cPCR using primer pair TOX5/Tox-8 showed non-specific amplification of porcine DNA.
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Affiliation(s)
- Nadja S Bier
- German Federal Institute for Risk Assessment (BfR), Department for Biological Safety, Berlin, Germany
| | - Gereon Schares
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald, Insel Riems, Germany
| | - Annette Johne
- German Federal Institute for Risk Assessment (BfR), Department for Biological Safety, Berlin, Germany
| | - Annett Martin
- German Federal Institute for Risk Assessment (BfR), Department for Exposure, Berlin, Germany
| | - Karsten Nöckler
- German Federal Institute for Risk Assessment (BfR), Department for Biological Safety, Berlin, Germany
| | - Anne Mayer-Scholl
- German Federal Institute for Risk Assessment (BfR), Department for Biological Safety, Berlin, Germany
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Analysis of Toxoplasma gondii clonal type-specific antibody reactions in experimentally infected turkeys and chickens. Int J Parasitol 2018; 48:845-856. [DOI: 10.1016/j.ijpara.2018.04.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/25/2018] [Accepted: 04/29/2018] [Indexed: 01/28/2023]
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Toxoplasma gondii infections in chickens – performance of various antibody detection techniques in serum and meat juice relative to bioassay and DNA detection methods. Int J Parasitol 2018; 48:751-762. [DOI: 10.1016/j.ijpara.2018.03.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 03/14/2018] [Accepted: 03/22/2018] [Indexed: 10/16/2022]
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Schares G, Bangoura B, Randau F, Goroll T, Ludewig M, Maksimov P, Matzkeit B, Sens M, Bärwald A, Conraths F, Opsteegh M, Van der Giessen J. High seroprevalence of Toxoplasma gondii and probability of detecting tissue cysts in backyard laying hens compared with hens from large free-range farms. Int J Parasitol 2017; 47:765-777. [DOI: 10.1016/j.ijpara.2017.07.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 07/04/2017] [Accepted: 07/11/2017] [Indexed: 01/05/2023]
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