Pathogen research includes studies on bacteria, mainly E. coli, Salmonella and Klebsiella spp, on the kinetoplastid parasites (Leishmania and Trypanosomes), and on the liver fluke Schistosoma.
The contribution of population heterogeneity and behavior to the success of pathogens is examined with a focus on the role of phase variation and biofilms. A cellular microbiology approach is used to understand how pathogens survive and grow within a host cell.
With Leishmania, research is focussed on parasite molecules that play a role in parasite transmission through sandflies and on enzymes essential for parasite survival.
Proteomic and functional approaches are being used to identify schistosome molecules that are involved in subverting host immunity.
The success of a bacterial pathogen depends on both the repertoire of genes and the regulatory networks that allow the optimal temporal and spatial expression. This requires integrating signals from the environment but in addition stochastic events generate heterogeneous expression patterns. These can lead to heterogenous phenotypes in a clonal population, which can be beneficial for example in immune evasion. The MvdW lab approaches this by identifying and understanding stochastic events, with a focus on epigenetic phase variation, and then determining how the regulation and the genes controlled contribute to the bacterial success. This work is shedding new insight into the virulence strategies of bacterial pathogens.
Biofilms are communities of cells that are attached to a surface. Biofilm formation on foreign surfaces in the body can lead to chronic infection and is difficult to treat due to enhanced resistance to antimicrobials and to eradication by the innate immune system. Understanding how bacterial populations are formed and disperse is essential to work towards strategies for intervention or treatment. We approach this problem considering the heterogeneity of bacterial populations, examining spatial and temporal processes that influence biofilm formation. This includes examining the effects of cell-cell interactions for population development and structure. We use advanced imaging techniques in combination with genetic approaches and bacterial physiology. Our focus is mainly on Gram-negative human pathogens, and we provide microbiology expertise to colleagues working on molecular aspects of Gram positive pathogens.
Novel antimicrobial therapies
Novel antimicrobial approaches are in demand more than ever in the face of constant increase in antibiotic resistance. A promising novel approach is biomedical plasma: ionized gas delivering antimicrobial species. In collaboration with colleagues at the York Plasma Institute, we are working to understand the molecular events underpinning the antimicrobial activity of plasma jets in context of future clinical applications, and to correlate that with the physical properties of the jet. This will contribute knowledge that will be required to develop plasma as a clinical therapy for infections.
Lysosomes form part of our innate immunity, yet successful intracellular pathogens, such as Salmonella, Chlamydia and Mycobacteria, are able to manipulate the host's trafficking machinery to enable them to avoid/delay delivery to the lysosome and thereby create their replicative niche. We are using the yeast Saccharomyces cerevisiae to identify pathogen proteins that alter membrane trafficking. We then find the mammalian targets of these proteins using a variety of cell biological techniques such as proteomics, fluorescent microscopy, photo-crosslinking, immunoprecipiation and affinity chromatography. Identifying the mammalian targets of the pathogen proteins allows us to dissect how the pathogen can survive intracellularly.
Parasitic protozoa give rise to some of the most widespread life-threatening human diseases in tropical and sub-tropical regions of the world. The kinetoplastid parasite Leishmania lives intracellularly in cells of the host immune system. Human leishmaniasis affects more than 15 million people in 88 countries, resulting in approximately 100,000 deaths annually, with a significant impact on health in developing countries. In southern Europe and countries bordering the Mediterranean, leishmaniasis is a major opportunist infection in HIV-infected individuals. The related extracellular parasite Trypanosoma brucei is the causative agent of African trypanosomiasis or Sleeping Sickness, which has long been a major cause of mortality in sub-Saharan Africa. T. brucei is also responsible for a major veterinary disease of livestock, with a huge potential impact on the economic development of endemic countries.
No vaccines are available to limit the spread of these diseases and current therapies depend on the use of highly toxic drugs that are expensive and difficult to administer in areas with a poor healthcare infrastructure. Emergence of drug-resistant parasites is adding to the disease burden. We are studying fundamental biological mechanisms as the first step towards the development of urgently required new drugs and vaccines to control these deadly pathogens.
We have validated the enzyme myristoyl CoA:protein N-myristoyltransferase (NMT) as a promising drug target against T. brucei and Leishmania spp. Highly potent and specific inhibitors against the parasite enzyme rapidly kill trypanosomes in vitro in the nanomolar range and critically, can cure infection in mice. Work is now in progress to identify and develop highly specific inhibitors of L. donovani NMT as part of a drug development programme for the most deadly form of visceral leishmaniasis.
We are also focusing on the functional analyses of infective-stage Leishmania proteins, including study of non-classical secretory pathways and antigen presentation mechanisms. We have recently shown that the Leishmania infective stage-specific proteins, HASPB and SHERP, are required for differentiation of parasites within the sand fly vector. In addition, we have interests in Leishmania proteomics, including the characterization and functional analysis of acylated proteins, and comparative functional genomics of Leishmania species that cause different types of clinical disease.
These interdisciplinary projects require a wide range of technical approaches from molecular and cell biology, via biochemistry and structural biology, to immunological analyses.
Research at CII
Kintz, E. Davies, MR, Hammarlӧf, D.L., Canals R. Hinton, J.C.D., and van der Woude M. (2015) A BTP1 prophage gene present in invasive non-typhoidal Salmonella determines composition and length of the O-antigen of the LPS. Mol Microbiol. doi: 10.1111/mmi.12933.
Adrian Mountford, (2015) Commensals regulate the schistosome response
James M. Fox, Richard Kasprowicz, Oliver Hartley and Nathalie Signoret CCR5 susceptibility to ligand-mediated down-modulation differs between human T lymphocytes and myeloid cells
J Leukoc Biol July 2015 98:59-71; doi:10.1189/jlb.2A0414-193RR