Understanding the interaction of the pathogenic intracellular bacterium <em>Coxiella </em>with the mammalian host: A metabolomics perspective — ASN Events
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  2. Poster Session B
  3. Understanding the interaction of the pathogenic intracellular bacterium Coxiella with the mammalian host: A metabolomics perspective

Understanding the interaction of the pathogenic intracellular bacterium Coxiella with the mammalian host: A metabolomics perspective (#310)

Nitika Neha 1 2 , David P De Souza 2 , Agnes Liew 1 , Hayley J Newton 3 , Fiona M Sansom 1
  1. Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, The University of Melbourne, Parkville, VIC, Australia
  2. Metabolomics Australia, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Parkville, VIC, Australia
  3. Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Parkville, VIC, Australia

Coxiella burnetii is an intracellular bacterium responsible for the zoonotic disease Q fever. A recent outbreak in the Netherlands cost over 300 million Euros to control, and resulted in long-term ill health in some patients. Until recently Coxiella was considered an obligate intracellular organism, hampering attempts to characterise its pathogenic mechanisms. The publication of axenic culture methods in 2009 facilitated the development of genetic manipulation methods for Coxiella, and has now enabled us to optimise methodology to apply metabolomics to Coxiella. This allows us to both dissect its central carbon metabolism, potentially identifying essential pathways and substrates, and to use metabolomics as a tool for functional characterisation of genes we have identified as required for intracellular growth. Following optimisation of quenching and metabolite extraction techniques, we compared the metabolite profiles of 6 day cultures, representing the replicating form of the bacteria (large cell variant; LCV), with the profiles of 20 day cultures that represent the non-replicating form of the bacteria (small cell variant; SCV). Historically, SCVs are considered to be metabolically inactive, and multivariate analysis revealed differing overall metabolic profiles for LCVs and SCVs, with specific differences in metabolites from glycolysis and the tricarboxylic acid (TCA) cycle. Interestingly, 13C-glucose labelling experiments demonstrated labelling of glycolytic and TCA cycle intermediates in both culture stages, suggesting that SCVs are metabolically active. Analysis of the metabolite profiles of wild type Coxiella and the cbu_0364 mutant, which lacks a gene encoding a putative transporter and is attenuated for growth inside mammalian cells, revealed a number of significantly different compounds. This will inform future transport assays to elucidate the function of CBU_0364. Our work is the first application of metabolomics technology to understanding Coxiella pathogenesis, and opens up many new avenues for investigation.

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