6 November 2015
Improved diagnostic tests may manage the spread of bovine tuberculosis in South Africa
The South African Medical Research Council’s Centre for Tuberculosis Research has developed a new diagnostic technique that will increase the detection of Mycobacterium bovis in infected animals.
The technique, which involves stimulation of whole blood with mycobacterial peptides using a modified human assay, was evaluated during the annual screening of buffalo herds for bovine tuberculosis in Hluhluwe-iMfolozi Game Reserve in South Africa. “We found an increased production of Cytokine IP-10 in stimulated whole blood from bovine TB positive buffalo which appears to be a more sensitive test than the currently used method of measuring interferon gamma,” said the Principal Investigators.
Cytokine IP-10 refers to the interferon gamma-induced protein 10.
Mycobacterium bovis is the causative agent of bovine tuberculosis (BTB) in a wide range of domestic animals and wildlife. BTB in cattle populations is intensively controlled in many countries since it poses a zoonotic risk as well as resulting in reduced productivity and death of infected animals. In South Africa, the African buffalo is a maintenance host of Mycobacterium bovis and the early detection of infected animals is important to control the transmission of the pathogen to other wildlife and domestic species as well as to prevent the geographic spread of this disease by translocation.
Currently African buffalo are tested using the tuberculin skin test which can result in both false positive and false negative results. Interferon gamma release assays utilizing pathogen-derived peptide antigens are highly specific, however they still remain a suboptimal biomarker. The findings suggest that measuring antigen-dependent interferon gamma-induced protein 10 (IP-10) release may be the alternative that will provide optimal detection.
“These findings suggest that this novel biomarker may be a potential diagnostic technique for improving detection of infected buffaloes in programs for the management and control of tuberculosis in wildlife,” investigators said.
The study was conducted in 2013 -2014 and is a collaborative effort between the SAMRC, NRF, and the Division of Molecular Biology and Human Genetics in the Faculty of Medicine and Health Sciences at Stellenbosch University. It was published in the August edition of Clinical and Vaccine Immunology.
NOTE TO THE EDITOR:
Principal Investigators & Authors
- Wynand J. Goosen completed his BSc (undergrad) and BSc (HonsMedSc) in Molecular Biology and Biotechnology at Stellenbosch University. During 2014 he successfully upgraded his MSc to a PhD in Molecular Biology and is currently full-time 2nd year PhD student. His project includes the evaluation of diagnostic assays utilizing M. bovis-specific antigens and the identification of novel diagnostic host biomarkers for the diagnosis of tuberculosis in African buffaloes (Syncerus caffer).
- Dr. David Cooper is the wildlife veterinarian for Emvezelo KZN Wildlife, and has been responsible for implementing the TB testing program of buffalo in Hluhluwe-iMfolzi Game Reserve. He is a key collaborator with the Animal TB Group and provides access to buffalo for sampling.
- Prof Michele A. Miller has a PhD in veterinary Immunology and has worked as a clinical wildlife veterinarian at a number of zoos and as a conservation medicine researcher. She holds the NRF SARChI Chair in Animal Tuberculosis and her current research focus is the immunology, epidemiology, management and control of tuberculosis in animals and those aspects that impact the human-animal interface.
- Prof Paul van Helden is Head of the Department of Biomedical Sciences and Director of the Stellenbosch node of the DST/NRF Centre for Excellence in Biomedical TB Research. He has a wide interest in many fields of animal tuberculosis including genetic host susceptibility to the disease as well as the aetiology, molecular epidemiology, immunology and diagnosis thereof.
- Dr Sven D. C. Parsons worked as a clinical veterinarian in private practice before doing an MSc in veterinary science and a PhD in Molecular Biology. His doctoral and postdoctoral work focussed primarily on the diagnostic immunology of animal TB. Additionally, he has an interest in unusual members of the Mycobacterium tuberculosis complex which are isolated from various wildlife species.
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