Understanding the pathogenesis of Burkholderia cenocepacia infections using blocking antibodies & novel chemistry scaffolds to untangle AMR complexity

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Burkholderia cenocepacia is an opportunistic Gram -ve bacterium which can infect CF patients and immuno-compromised cancer patients undergoing chemotherapy. In CF B. cenocepacia causes a severe (and irreversible) decline in lung function resulting in a life-threatening systemic infection known as cepacia syndrome. B. cenocepacia is intrinsically resistant to multiple classes of antimicrobial agents (hiding away inside cells) and expresses an array of virulence factors. This PhD will develop specific blocking tools that can be used to disarm different components of the bacteria's pathogenic arsenal. One strategy that will be studied in detail is a systemic resistance mechanism that neutralises the potency of existing antibiotic approaches. Interestingly, because of its promiscuous nature, deployment of this approach by B. cenocepacia can even encourage infection from other obligate or non-obligate pathogens. In B. cenocepacia, exposure to sublethal concentrations of antibiotics induces chemotoxic stress which results in the expression and secretion, into the extracellular environment, of a group of conserved bacterial proteins called lipocalins (our focus BcnA) which intercept and sequester antibiotics before these drugs can reach the bacteria inside cells. This aspect of the bacteria's infection strategy can be partially reversed by natural compounds such as Vitamin E which increases antimicrobial sensitivity by inhibiting bacterial lipocalin/antibiotic binding through mechanisms that appear to be both antioxidant and/or through the blocking of lipid peroxidation (both recognised MoAs of Vit E). Here we propose a more detailed and two-pronged strategy to further interrogate and hopefully manipulate the BcnA system. We will develop anti-BcnA antibodies (mAbs) as tools to stop BcnA mopping up antibiotics, whilst at the same time we hope in vivo (mouse) these same mAbs will encourage the mouse immune system to mop-up and neutralise the BcnA molecules. These mAbs may have a third exciting use as diagnostic probes to identify BcnA molecules in urine as an early and specific indicator of infection. In parallel we will use a new super-antioxidant (called Proxison) to determine its protective effects. Whilst a potent molecule (500x Vit E) with a similar MoA, this currently is a molecule with poor bioavailability. One key part of this project will be to use chemistry to design and synthesise more bioavailable versions (pro-drug and biotransformation chemistries) that retain this impressive potency but have improved utility in vitro and hopefully in vivo. The final aims of this PhD would be to combine the use of these two strategies and determine their effects on B. cenocepacia biology. This project will be based in the Scottish Biologics Facility which has developed an international reputation for recombinant antibody generation and is a centre of training excellence in protein engineering and biologics drug discovery, including phage display. The PhD will also require training in medicinal chemistry and the manipulation of the existing scaffold to improve bioavailability (Chemistry Dept and Institute of Medical Sciences). Finally the project will involve microbiological training including the use of in vivo infection models.