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Adaptation and Diagnostic Potential of a Commercial Cat Interferon Gamma Release Assay for the Detection of Mycobacterium bovis Infection in African Lions (Panthera leo). Pathogens 2022; 11:pathogens11070765. [PMID: 35890010 PMCID: PMC9317741 DOI: 10.3390/pathogens11070765] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 06/28/2022] [Accepted: 07/01/2022] [Indexed: 11/25/2022] Open
Abstract
Mycobacterium bovis (M. bovis) infection in wildlife, including lions (Panthera leo), has implications for individual and population health. Tools for the detection of infected lions are needed for diagnosis and disease surveillance. This study aimed to evaluate the Mabtech Cat interferon gamma (IFN-γ) ELISABasic kit for detection of native lion IFN-γ in whole blood samples stimulated using the QuantiFERON® TB Gold Plus (QFT) platform as a potential diagnostic assay. The ELISA was able to detect lion IFN-γ in mitogen-stimulated samples, with good parallelism, linearity, and a working range of 15.6–500 pg/mL. Minimal matrix interference was observed in the recovery of domestic cat rIFN-γ in lion plasma. Both intra- and inter-assay reproducibility had a coefficient of variation less than 10%, while the limit of detection and quantification were 7.8 pg/mL and 31.2 pg/mL, respectively. The diagnostic performance of the QFT Mabtech Cat interferon gamma release assay (IGRA) was determined using mycobacterial antigen-stimulated samples from M. bovis culture-confirmed infected (n = 8) and uninfected (n = 4) lions. A lion-specific cut-off value (33 pg/mL) was calculated, and the sensitivity and specificity were determined to be 87.5% and 100%, respectively. Although additional samples should be tested, the QFT Mabtech Cat IGRA could identify M. bovis-infected African lions.
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CYTOKINE-RELEASE ASSAY FOR THE DETECTION OF MYCOBACTERIUM BOVIS INFECTION IN CHEETAH ( ACINONYX JUBATUS). J Zoo Wildl Med 2022; 52:1113-1122. [PMID: 34998280 DOI: 10.1638/2021-0063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/16/2021] [Indexed: 11/21/2022] Open
Abstract
The lack of species-specific assays for the diagnosis of infectious diseases, such as bovine tuberculosis, poses a threat to the management of wildlife populations, especially for vulnerable species such as cheetah (Acinonyx jubatus). The aim of this study was to identify and develop a cell-mediated immunological cytokine-release assay that could distinguish between Mycobacterium bovis-infected and uninfected cheetahs using commercially available feline cytokine ELISA and domestic cat (Felis catus) recombinant proteins. Antibodies against domestic cat cytokines, tumour necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), and interferon gamma (IFN-γ), were screened for cross-reactivity with plasma cytokines from cheetah whole blood stimulated using QuantiFERON®-TB Gold Plus (QFT) tubes. Evidence of cytokine production in response to QFT mitogen stimulation was observed in all four ELISA assays. However only the Mabtech Cat IFN-γ ELISABasic kit could distinguish between M. bovis-infected (n = 1) and uninfected (n = 1) cheetahs and was therefore selected for further evaluation. A preliminary cheetah specific cutoff value (11 pg/ml) for detecting M. bovis infection using the Mabtech Cat IFN-γ release assay was calculated using a M. bovis uninfected cheetah cohort. Although this study only included one confirmed M. bovis culture-positive and one M. bovis culture-negative cheetah, the Mabtech Cat IFN-γ release assay demonstrated its potential for diagnostic application in this species.
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Mitchell JL, Raper A, Gunn-Moore DA, Hope JC. Recognition of recombinant interferon-gamma from Felidae species by anti-cat antibodies. Vet Immunol Immunopathol 2021; 241:110327. [PMID: 34564047 DOI: 10.1016/j.vetimm.2021.110327] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 09/15/2021] [Accepted: 09/18/2021] [Indexed: 11/29/2022]
Abstract
Mycobacterial infections cause a reasonable burden of morbidity and mortality in global feline populations, many of which are 'Vulnerable' or 'Endangered'. Identifying these infections may facilitate efforts to protect these animals. An interferon-gamma (IFNγ) release assay (IGRA) to diagnose mycobacteriosis in domestic cats has been adapted for use in lions; however, the development of species-specific antibodies may be laborious. Therefore, we investigated whether anti-cat IFNγ antibodies can bind to recombinant IFNγ (rIFNγ) from other Felidae species, permitting use of the feline IGRA in a wider range of felids. Unique Felidae IFNγ protein sequences and their corresponding coding nucleotide sequence were identified from online databases; plasmids with an IFNγ-gene insert were synthesised to transform E. coli-DH5α and subsequently transfect HEK 293 T cells to secrete rIFNγ. Enzyme-linked immunosorbent assay using a commercial anti-cat IFNγ kit was performed to detect rIFNγ from Felidae, the domestic dog and cattle. Five unique rIFNγ Felidae proteins were synthesised; anti-cat IFNγ antibodies were able to bind to all five proteins, while cross-reactivity with canine and bovine rIFNγ was negligible. This suggests that anti-cat IFNγ antibodies are sufficient for detection of IFNγ across other Felidae species, namely the lion, tiger, cheetah, cougar, Iberian lynx and the Canadian lynx.
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Affiliation(s)
- Jordan L Mitchell
- The Royal (Dick) School of Veterinary Studies and The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, United Kingdom.
| | - Anna Raper
- The Royal (Dick) School of Veterinary Studies and The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, United Kingdom
| | - Danièlle A Gunn-Moore
- The Royal (Dick) School of Veterinary Studies and The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, United Kingdom
| | - Jayne C Hope
- The Royal (Dick) School of Veterinary Studies and The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, United Kingdom
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Mitchell JL, Stanley P, McDonald K, Burr P, Rhodes SG, Gunn-Moore DA, Hope JC. Diagnostic accuracy of the interferon-gamma release assay (IGRA) for cases of feline mycobacteriosis. Prev Vet Med 2021; 193:105409. [PMID: 34126470 DOI: 10.1016/j.prevetmed.2021.105409] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/22/2021] [Accepted: 06/06/2021] [Indexed: 10/21/2022]
Abstract
The aim of this study was to evaluate the sensitivity and specificity of the interferon-gamma release assay (IGRA) for diagnosing infections with members of the Mycobacterium (M.) tuberculosis-complex (MTBC) and non-tuberculous mycobacteria (NTM) in domestic cats, and to generate defined feline-specific cut-off values using receiver operating characteristic (ROC) curve analysis to improve test performance. Records of 594 cats that had been tested by IGRA were explored to identify individuals that had a culture and/or polymerase chain reaction (PCR)-confirmed case of mycobacterial disease, and those that had a final diagnosis of non-mycobacterial disease. A total of 117 cats - 80 with mycobacterial disease and 37 diagnosed with a condition other than mycobacteriosis - were identified for further detailed analysis. This population was used to estimate test sensitivity and specificity, as well as likelihood ratios for the IGRA to correctly identify a cat with or without mycobacterial disease. Agreement between IGRA results and culture/PCR using current and proposed new cut-off values was also determined. ROC analysis of defined confirmed infected and non-mycobacterial disease control cats allowed an adjustment of current test cut-offs that increased the overall test sensitivity for MTBC infections from 83.1 % (95 % confidence interval [CI]: 71.5-90.5 %) to 90.2 % (95 % CI: 80.2-95.4%), and M. bovis infection from 43 % (95 % CI: 28.2-60.7%) to 68 % (95 % CI: 51.4-82.1%) while maintaining high test specificity (100 % in both cases). Overall agreement between IGRA results and culture/PCR, while recognising that neither culture nor PCR tests have perfect sensitivity, improved from weak (κ = 0.57) to moderate (κ = 0.71) using new proposed IGRA test cut-off values. Application of these results, based upon the statistical analysis of accumulated test data, can improve the diagnostic performance of the feline IGRA, particularly for identifying infections with M. bovis, without compromising specificity.
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Affiliation(s)
- Jordan L Mitchell
- The Royal (Dick) School of Veterinary Studies and The Roslin Institute, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, United Kingdom.
| | - Paul Stanley
- The Royal (Dick) School of Veterinary Studies and The Roslin Institute, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, United Kingdom
| | - Kieran McDonald
- Biobest Laboratories Ltd, 6 Charles Darwin House, Edinburgh Technopole, Milton Bridge, Near Penicuik, EH26 0PY, United Kingdom
| | - Paul Burr
- Biobest Laboratories Ltd, 6 Charles Darwin House, Edinburgh Technopole, Milton Bridge, Near Penicuik, EH26 0PY, United Kingdom
| | - Shelley G Rhodes
- Animal & Plant Health Agency, Woodham Lane, New Haw, Addlestone, Surrey, KT15 3NB, United Kingdom
| | - Danièlle A Gunn-Moore
- The Royal (Dick) School of Veterinary Studies and The Roslin Institute, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, United Kingdom
| | - Jayne C Hope
- The Royal (Dick) School of Veterinary Studies and The Roslin Institute, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, United Kingdom
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CONSERVATION CHALLENGES: THE LIMITATIONS OF ANTEMORTEM TUBERCULOSIS TESTING IN CAPTIVE ASIATIC LIONS ( PANTHERA LEO PERSICA). J Zoo Wildl Med 2020; 51:426-432. [PMID: 32549574 DOI: 10.1638/2019-0084] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/16/2020] [Indexed: 11/21/2022] Open
Abstract
Genetic diversity of captive wild animals can be enhanced by moving those individuals with valuable genes between collections and through introduction of a new pair from a range country. This requires movement of animals, which is inherent with disease risks, such as the introduction of pathogenic Mycobacterium sp. (MTBC) into a zoological collection. Decisions need to be made based on the outcome of perimovement disease screening using an array of tests, the majority of which are unvalidated in the species. A pair of endangered Asiatic lions (Panthera leo persica) imported from India to the United Kingdom were screened for MTBC using the comparative intradermal tuberculosis (TB) test, the feline interferon-γ blood test, and the experimental bacteriophage assay. Reactions on all three tests prompted screening of the three resident Asiatic lions using the same tests, all of which were negative for MTBC. Based on these test results, the decision had to be made to exclude the genetically valuable pair from the current collection. MTBC could not be identified using further tests, including culture and PCR on a bronchoalveolar lavage, on feces, or on postmortem tissues. This case series highlights the usefulness of a control group when interpreting unvalidated test results for detection of MTBC, the value of training big cats for conscious blood sampling, and the practical implications of placing the comparative intradermal TB test in the eyelids, when dealing with a species that requires a general anesthetic for most hands-on interventions.
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Songthammanuphap S, Puthong S, Pongma C, Buakeaw A, Prammananan T, Warit S, Tipkantha W, Kaewkhunjob E, Yindeeyoungyeon W, Palaga T. Detection of Mycobacterium tuberculosis complex infection in Asian elephants (Elephas maximus) using an interferon gamma release assay in a captive elephant herd. Sci Rep 2020; 10:14551. [PMID: 32883961 PMCID: PMC7471291 DOI: 10.1038/s41598-020-71099-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 08/10/2020] [Indexed: 11/25/2022] Open
Abstract
Tuberculosis is highly contagious disease that can be transmitted between humans and animals. Asian elephants (Elephas maximus) in captivity live in close contact with humans in many Asian countries. In this study, we developed an interferon gamma release assay (IGRA) for elephant TB detection using antigens from the MTB complex (MTBC) and nontuberculous mycobacteria (NTM) as stimulating antigens (PPD, ESAT6, CFP10) to elicit a cell-mediated immune response (CMIR). The developed assay was applied to an elephant herd of more than 60 animals in Thailand, and the results were compared with those obtained through serological detection. IGRA has sufficient sensitivity for detecting elephant interferon gamma (eIFNγ) from specific antigen-stimulated PBMCs. Among 60 animals tested, 20 samples (33.3%) showed negative results for both MTBC and NTM infection. Eighteen samples (30%) showed positive responses against PPD from M. bovis and/or ESAT6 and CFP10, indicating MTBC infection. In contrast, only 15.6% showed seropositivity in a commercial serological test kit for elephant TB. The discrepancies between serological and CMIR highlight that the two methods may detect different stages of elephant TB. Therefore, employing both tests may enable them to complement each other in correctly identifying elephants that have been exposed to MTBC.
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Affiliation(s)
- Songkiat Songthammanuphap
- Graduate Program in Microbiology and Microbial Technology, Department of Microbiology, Faculty of Science, Chulalongkorn University, Phayathai Road, Pathumwan, Bangkok, 10330, Thailand.,Center of Excellence in Immunology and Immune-Mediated Diseases, Chulalongkorn University, Phayathai Road, Pathumwan, Bangkok, 10330, Thailand
| | - Songchan Puthong
- Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Phayathai Road, Pathumwan, Bangkok, 10330, Thailand
| | - Chitsuda Pongma
- Center of Excellence in Immunology and Immune-Mediated Diseases, Chulalongkorn University, Phayathai Road, Pathumwan, Bangkok, 10330, Thailand.,Inter-Department Graduate Program in Biotechnology, Faculty of Science, Chulalongkorn University, Phayathai Road, Pathumwan, Bangkok, 10330, Thailand
| | - Anumart Buakeaw
- Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Phayathai Road, Pathumwan, Bangkok, 10330, Thailand
| | - Therdsak Prammananan
- The National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency (NSTDA), 113 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand
| | - Saradee Warit
- The National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency (NSTDA), 113 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand
| | - Wanlaya Tipkantha
- The Zoological Park Organization of Thailand, Bureau of Conservation and Research, Pracharat Sai 1 Road, BangSue, Bangkok, 10800, Thailand
| | - Erngsiri Kaewkhunjob
- The Zoological Park Organization of Thailand, Bureau of Conservation and Research, Pracharat Sai 1 Road, BangSue, Bangkok, 10800, Thailand
| | - Wandee Yindeeyoungyeon
- The National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency (NSTDA), 113 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand.
| | - Tanapat Palaga
- Graduate Program in Microbiology and Microbial Technology, Department of Microbiology, Faculty of Science, Chulalongkorn University, Phayathai Road, Pathumwan, Bangkok, 10330, Thailand. .,Center of Excellence in Immunology and Immune-Mediated Diseases, Chulalongkorn University, Phayathai Road, Pathumwan, Bangkok, 10330, Thailand.
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Roux L, McCall AJ, Michel AL. Detection of native interferon-γ in nyala (Tragelaphus angasii): Towards diagnosing tuberculosis. ACTA ACUST UNITED AC 2019; 86:e1-e3. [PMID: 31714142 PMCID: PMC6852497 DOI: 10.4102/ojvr.v86i1.1796] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 08/19/2019] [Accepted: 08/27/2019] [Indexed: 01/01/2023]
Abstract
Mycobacterium bovis is the main cause of tuberculosis in wildlife. In South Africa, African buffaloes (Syncerus caffer) are a wildlife maintenance host while a number of other species are considered spillover hosts. Nyala (Tragelaphus angasii), a large antelope species from Southern Africa, is frequently traded and can be infected with M. bovis. Interferon gamma (IFN-γ) release assays that detect cell-mediated immune (CMI) responses to M. bovis infection have shown promise in elephants, rhinoceroses and buffaloes. The BOVIGAM® assay is a commercial IFN-γ release assay designed to detect tuberculosis in cattle and has been validated in buffaloes. We tested the suitability of the BOVIGAM® assay to detect native IFN-γ release in nyala. Blood samples collected from 17 nyalas were stimulated with different mitogens and IFN-γ release measured. We found that incubating whole blood with phorbol 12-myristate 13-acetate and calcium ionophore (PMA/CaI) resulted in the highest levels of IFN-y release. Samples stimulated with tuberculin purified protein derivatives of M. bovis (PPDb) and M. avium (PPDa) did not show significant IFN-γ production. An intradermal tuberculin test (IDT) and culture of tissues from 15 of the 17 culled nyala were also performed, which supported the findings of the BOVIGAM® assay, suggesting the potential value of this assay for the diagnosis of tuberculosis in nyala.
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Affiliation(s)
- Lezaan Roux
- Department of Veterinary Tropical Diseases, Bovine Tuberculosis and Brucellosis Research Programme, Faculty of Veterinary Science, University of Pretoria, Onderstepoort.
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Paudel S, Villanueva MA, Mikota SK, Nakajima C, Gairhe KP, Subedi S, Rayamajhi N, Sashika M, Shimozuru M, Matsuba T, Suzuki Y, Tsubota T. Development and evaluation of an interferon-γ release assay in Asian elephants (Elephas maximus). J Vet Med Sci 2016; 78:1117-21. [PMID: 26983683 PMCID: PMC4976266 DOI: 10.1292/jvms.15-0701] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
We developed an interferon-γ release assay (IGRA) specific for Asian elephants
(Elephas maximus). Whole blood collected from forty captive Asian
elephants was stimulated with three different mitogens i.e., phytohemagglutinin (PHA),
pokweed mitogen (PWM) and phorbol myristate aceteate/ionomycin (PMA/I). A sandwich ELISA
that was able to recognize the recombinant elephant interferon-γ (rEIFN-γ) as well as
native interferon-γ from the Asian elephants was performed using anti-elephant IFN-γ
rabbit polyclonal antibodies as capture antibodies and biotinylated anti-elephant IFN-γ
rabbit polyclonal antibodies as detection antibodies. PMA/I was the best mitogen to use as
a positive control for an Asian elephant IGRA. The development of an Asian
elephant-specific IGRA that detects native IFN-γ in elephant whole blood provides
promising results for its application as a potential diagnostic tool for diseases, such as
tuberculosis (TB) in Asian elephants.
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Affiliation(s)
- Sarad Paudel
- Laboratory of Wildlife Biology and Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, Hokkaido 060-0818, Japan
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Olivier TT, Viljoen IM, Hofmeyr J, Hausler GA, Goosen WJ, Tordiffe ASW, Buss P, Loxton AG, Warren RM, Miller MA, van Helden PD, Parsons SDC. Development of a Gene Expression Assay for the Diagnosis ofMycobacterium bovisInfection in African Lions (Panthera leo). Transbound Emerg Dis 2015; 64:774-781. [DOI: 10.1111/tbed.12436] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Indexed: 11/26/2022]
Affiliation(s)
- T. T. Olivier
- DST-NRF Centre of Excellence for Biomedical Tuberculosis Research/SAMRC Centre for TB Research/Division of Molecular Biology and Human Genetics; Faculty of Medicine and Health Sciences; Stellenbosch University; Tygerberg South Africa
| | - I. M. Viljoen
- DST-NRF Centre of Excellence for Biomedical Tuberculosis Research/SAMRC Centre for TB Research/Division of Molecular Biology and Human Genetics; Faculty of Medicine and Health Sciences; Stellenbosch University; Tygerberg South Africa
| | - J. Hofmeyr
- Veterinary Wildlife Services; Kruger National Park; Skukuza South Africa
| | - G. A. Hausler
- DST-NRF Centre of Excellence for Biomedical Tuberculosis Research/SAMRC Centre for TB Research/Division of Molecular Biology and Human Genetics; Faculty of Medicine and Health Sciences; Stellenbosch University; Tygerberg South Africa
| | - W. J. Goosen
- DST-NRF Centre of Excellence for Biomedical Tuberculosis Research/SAMRC Centre for TB Research/Division of Molecular Biology and Human Genetics; Faculty of Medicine and Health Sciences; Stellenbosch University; Tygerberg South Africa
| | - A. S. W. Tordiffe
- Department of Paraclinical Sciences; Faculty of Veterinary Science; University of Pretoria; Pretoria South Africa
- National Zoological Gardens of South Africa; Pretoria South Africa
| | - P. Buss
- Veterinary Wildlife Services; Kruger National Park; Skukuza South Africa
| | - A. G. Loxton
- DST-NRF Centre of Excellence for Biomedical Tuberculosis Research/SAMRC Centre for TB Research/Division of Molecular Biology and Human Genetics; Faculty of Medicine and Health Sciences; Stellenbosch University; Tygerberg South Africa
| | - R. M. Warren
- DST-NRF Centre of Excellence for Biomedical Tuberculosis Research/SAMRC Centre for TB Research/Division of Molecular Biology and Human Genetics; Faculty of Medicine and Health Sciences; Stellenbosch University; Tygerberg South Africa
| | - M. A. Miller
- DST-NRF Centre of Excellence for Biomedical Tuberculosis Research/SAMRC Centre for TB Research/Division of Molecular Biology and Human Genetics; Faculty of Medicine and Health Sciences; Stellenbosch University; Tygerberg South Africa
| | - P. D. van Helden
- DST-NRF Centre of Excellence for Biomedical Tuberculosis Research/SAMRC Centre for TB Research/Division of Molecular Biology and Human Genetics; Faculty of Medicine and Health Sciences; Stellenbosch University; Tygerberg South Africa
| | - S. D. C. Parsons
- DST-NRF Centre of Excellence for Biomedical Tuberculosis Research/SAMRC Centre for TB Research/Division of Molecular Biology and Human Genetics; Faculty of Medicine and Health Sciences; Stellenbosch University; Tygerberg South Africa
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Morar D, Schreuder J, Mény M, van Kooten PJS, Tijhaar E, Michel AL, Rutten VPMG. Towards establishing a rhinoceros-specific interferon-gamma (IFN-γ) assay for diagnosis of tuberculosis. Transbound Emerg Dis 2014; 60 Suppl 1:60-6. [PMID: 24171850 DOI: 10.1111/tbed.12132] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Indexed: 11/30/2022]
Abstract
Mycobacterium bovis is the causal agent of bovine tuberculosis (BTB), with a diverse host range, extending from livestock to domestic and captive wild animals as well as free-ranging wildlife species. In South Africa, BTB is endemic in the Kruger National Park (KNP) and the Hluluwe iMfolozi National Park (HiP), where the high prevalence of M. bovis infections in buffalo herds has led to infection of a number of wildlife species. This has raised concerns about the spillover into the rhinoceros population, a species known to be susceptible to both M. bovis and Mycobacterium tuberculosis, jeopardizing breeding and relocation projects that serve to conserve and protect this species. In view of the advantages of the interferon-gamma (IFN-γ) assay in the diagnosis of BTB in a variety of species worldwide, such an assay has been developed for rhinoceroses by Morar and co-workers in 2007. In this study, this assay was optimized using recombinant eukaryotic rhinoceros IFN-γ and the lower detection limit was calculated to be 0.5 ng/ml. Subsequently, assessing the detection of native rhinoceros IFN-γ protein in whole-blood samples revealed stimulation with each of the mitogens: pokeweed (PWM), phytohaemagglutinin (PHA) & phorbol 12-myristate 13-acetate and calcium ionophore (PMA/CaI), though most prominently with the latter two. In addition, samples collected from 52 clinically healthy rhinoceroses, of presumed negative BTB status, from two different areas in South Africa were used to determine the cut-off value for a negative test result. This was calculated to be 0.10 (OD490 nm ) and as determined in this study is a preliminary recommendation based on IFN-γ responses observed in samples from BTB-free rhinoceroses only.
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Affiliation(s)
- D Morar
- Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
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