Proceedings of the 10th International Colloquium on Paratuberculosis

#146 Analysis <strong>of</strong> volatile organic compounds in sera - a future prospect <strong>of</strong> paratuberculosis
diagnosis?
Henri Knobloch, Nicola J Commander, Petra Reinhold, Claire Turner, Andrew Spooner, Mark A Chambers,
Heike U Köhler
Cranfield Health, Cranfield University, Cranfield, Bedfordshire, United Kingdom; Veterinary Laboratories Agency:
Weybridge, New Haw, Addlestone, Surrey, United Kingdom; Institute <strong>of</strong> Molecular Pathogenesis, Friedrich-Loeffler-
Institut, Jena, Germany
Objective: Paratuberculosis (paraTB) in <strong>the</strong> early stages <strong>of</strong> disease is difficult to diagnose due to <strong>the</strong> low
sensitivity <strong>of</strong> established direct and indirect diagnostic methods. Alternative diagnostic methods, which indicate
host-pathogen interaction, may have some value in improving <strong>the</strong> sensitivity <strong>of</strong> diagnosis. Therefore, an
electronic nose was evaluated for <strong>the</strong> ability to discriminate <strong>the</strong> infection status <strong>of</strong> animals through analysis <strong>of</strong>
<strong>the</strong> volatile organic compounds (VOC) present in sera. Electronic noses consist <strong>of</strong> an array <strong>of</strong> non-specific gas
sensors and require complex data analyses. In this study, <strong>the</strong> ability <strong>of</strong> <strong>the</strong> e-nose technology to discriminate
<strong>the</strong> sera <strong>of</strong> paraTB infected- Brucella infected- and healthy cattle was assessed.
Materials and Methods: A total <strong>of</strong> 117 sera from cattle, naturally infected with paraTB (n=43) or
brucellosis (n=26) and from corresponding control animals (2 x 24) were analysed randomly and blinded to
<strong>the</strong>ir infection status using a ST 214 e-nose (Scensive Ltd, Leeds, UK). Samples were collected under field
conditions on different farms. Sensor responses were analysed using multifactor ANOVA, linear regression and
homogeneity testing for biological and methodological variation as well as principle component analysis (PCA)
to identify <strong>the</strong> most powerful factors.
Results: Sensor responses <strong>of</strong> <strong>the</strong> device were influenced by methodological and biological factors.
Despite <strong>of</strong> that, significant differences between populations <strong>of</strong> paraTB infected, Brucella infected, and healthy
animals were detected. However, due to <strong>the</strong> methodological variation, discrimination between single individuals
was not possible.
Conclusions: This particular e-nose cannot be used as a diagnostic tool for paraTB or Brucella detection
and classification. Never<strong>the</strong>less, <strong>the</strong> data indicates that <strong>the</strong>re are differences in <strong>the</strong> sensor responses dependent
upon disease status, and <strong>the</strong>refore suggests that analysis <strong>of</strong> volatiles may be exploited in future for <strong>the</strong>
identification <strong>of</strong> disease specific biomarkers for paraTB and o<strong>the</strong>r infectious diseases.
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