Dataset Information

Development and evaluation of an interferon gamma assay for the diagnosis of tuberculosis in red deer experimentally infected with Mycobacterium bovis.

ABSTRACT:

Background

Red deer (Cervus elaphus) is regarded as an epidemiologically relevant host for Mycobacterium bovis (M. bovis) and closely related members of the Mycobacterium tuberculosis complex that cause animal tuberculosis (TB). The standard antemortem screening test for the detection of TB in deer is the intradermal tuberculin skin test, but the detection of interferon-gamma (IFN?) produced by white blood cells exposed to M. bovis antigens can be used as an alternative or supplemental assay in most TB eradication/control programs. This study aims to develop an in-house sandwich ELISA for deer IFN?, based on the cross-reactivity of the antibodies to both cervid and bovine IFN?, and to evaluate the potential of this assay to detect M. bovis-infected red deer in response to the in vitro stimulation of whole-blood cells with bovine purified protein derivative (bPPD), p22 protein complex derived from bPPD or using the specific tuberculous mycobacterial proteins ESAT-6/CFP-10, Rv3615c and Rv3020c. The positive control stimulant used in this study was pokeweed mitogen, which resulted in a consistent induction of IFN? in samples from red deer, thus allowing the interpretation of the assay.

Results

The percentage of animals correctly classified by this technique as M. bovis non-infected was 100%. The detection of infected animals as positive was high and ranged widely depending upon the antigen and the cut-off value applied, as well as the time after infection. Our findings indicate that this protocol may serve as a reliable assay for the antemortem diagnosis of TB from the initial stage of M. bovis-infection, and may also be adequately sensitive.

Conclusions

The suggested optimal antigens and cut-off are bPPD, p22 and the combination of ESAT-6/CFP-10 and Rv3020c with a 0.05 ? optical density, which yielded a up to 100% correct classification of TB positive and negatve red deer under our experimental conditions. This technique will aid in TB testing of farmed and translocated deer. Future studies should evaluate the ability of this IFN? assay to detect specific responses under field conditions.

SUBMITTER: Risalde MA

PROVIDER: S-EPMC5691593 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

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Publications

Development and evaluation of an interferon gamma assay for the diagnosis of tuberculosis in red deer experimentally infected with Mycobacterium bovis.

Risalde María Ángeles MÁ Thomas Jobin J Sevilla Iker I Serrano Miriam M Ortíz Jose Antonio JA Garrido Joseba J Domínguez Mercedes M Domínguez Lucas L Gortázar Christian C Ruíz-Fons Jose Francisco JF

BMC veterinary research 20171116 1

<h4>Background</h4>Red deer (Cervus elaphus) is regarded as an epidemiologically relevant host for Mycobacterium bovis (M. bovis) and closely related members of the Mycobacterium tuberculosis complex that cause animal tuberculosis (TB). The standard antemortem screening test for the detection of TB in deer is the intradermal tuberculin skin test, but the detection of interferon-gamma (IFNγ) produced by white blood cells exposed to M. bovis antigens can be used as an alternative or supplemental a ...[more]

PMID: 29145844

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Project description:Reactive oxygen and nitrogen species (ROS-RNS) are important defence substances involved in the immune response against pathogens. An excessive increase in ROS-RNS, however, can damage the organism causing oxidative stress (OS). The organism is able to neutralise OS by the production of antioxidant enzymes (AE); hence, tissue damage is the result of an imbalance between oxidant and antioxidant status. Though some work has been carried out in humans, there is a lack of information about the oxidant/antioxidant status in the presence of tuberculosis (TB) in wild reservoirs. In the Mediterranean Basin, wild boar (Sus scrofa) is the main reservoir of TB. Wild boar showing severe TB have an increased risk to Mycobacterium spp. shedding, leading to pathogen spreading and persistence. If OS is greater in these individuals, oxidant/antioxidant balance in TB-affected boars could be used as a biomarker of disease severity. The present work had a two-fold objective: i) to study the effects of bovine TB on different OS biomarkers (namely superoxide dismutase (SOD), catalasa (CAT), glutathione peroxidase (GPX), glutathione reductase (GR) and thiobarbituric acid reactive substances (TBARS)) in wild boar experimentally challenged with Mycobacterium bovis, and ii) to explore the role of body weight, sex, population and season in explaining the observed variability of OS indicators in two populations of free-ranging wild boar where TB is common. For the first objective, a partial least squares regression (PLSR) approach was used whereas, recursive partitioning with regression tree models (RTM) were applied for the second. A negative relationship between antioxidant enzymes and bovine TB (the more severe lesions, the lower the concentration of antioxidant biomarkers) was observed in experimentally infected animals. The final PLSR model retained the GPX, SOD and GR biomarkers and showed that 17.6% of the observed variability of antioxidant capacity was significantly correlated with the PLSR X's component represented by both disease status and the age of boars. In the samples from free-ranging wild boar, however, the environmental factors were more relevant to the observed variability of the OS biomarkers than the TB itself. For each OS biomarker, each RTM was defined as a maximum by one node due to the population effect. Along the same lines, the ad hoc tree regression on boars from the population with a higher prevalence of severe TB confirmed that disease status was not the main factor explaining the observed variability in OS biomarkers. It was concluded that oxidative damage caused by TB is significant, but can only be detected in the absence of environmental variation in wild boar.

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Dataset Information

Development and evaluation of an interferon gamma assay for the diagnosis of tuberculosis in red deer experimentally infected with Mycobacterium bovis.

Background

Results

Conclusions

Publications

Development and evaluation of an interferon gamma assay for the diagnosis of tuberculosis in red deer experimentally infected with Mycobacterium bovis.

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