Professor
McGill University
21,111 Lakeshore Road
Ste Anne de Bellevue, QC, H9X 3V9
Office: (514) 398-8668
Fax: (514) 398-7857
Email: john [dot] dalton [at] mcgill [dot] ca
Research Interests
My research interest has always centered on the understanding of the biology and biochemistry of parasitic organisms, and on the interplay between parasites and their hosts. In particular, I am interested in the molecules that parasites release to alter the physiology of their hosts. Of critical importance is how parasites manipulate host immune responses to their advantage. While many aspects of this research are basic, the ultimate goal is the discovery of a strategy(s) by which we can protect animals and humans from parasitic infections by either chemotherapeutic (drugs) or immunological (vaccines) means. Accordingly, I have always been cognizant of the applied and/or commercial potential of the work which led to the development of ildana Biotech, Ireland (see below).
More specifically, in my research on malaria (Plasmodium sp.) we have identified several aminopeptidase enzymes which the parasites employ to release amino acids from haemoglobin within erythrocytes. The parasites utilize these amino acids for protein anabolism and, hence, as our studies show, blocking of these enzymes with broad-range or specific inhibitors prevent parasite growth. We have recently discovered several lead compounds with in vivo activity against rodent models of malaria that will be used for the future development of novel antimalarials.
Research on the Schistosoma sp., the causative agents of schistosomiasis in animals and man, has led to the isolation and characterisation of a battery of enzymes that the parasite employs to systematically degrade haemoglobin from host red blood cells which they use as nutrient. Apart from characterizing the physico- and biochemico-properties of these enzymes we have used these as vaccines using mouse model systems of schistosomiasis mansoni.
Research on liver fluke disease (Fasciola hepatica) has characterised a number of proteolytic enzymes that the parasite uses to penetrate tissue and to obtain nutrients from the host. Other molecules, such as the anti-oxidants, peroxiredoxins, are involved in detoxifying ROS derived from parasite metabolism or by immune effector cells. Our recent studies have demonstrated a role for cathepsin Ls and peroxiredoxin in modulating the host’s innate immune mechanisms. Recombinant forms of these enzymes are in experimental trials as vaccines against liver fluke infection of ruminants.
We have expanded our area of interest to include the immunology of infectious diseases, the regulation of immune responses by parasites and the cross-regulation of immune response between parasitic infections and concurrent infection with bacterial pathogens such as Bordetella pertussis and Salmonella sp., and protozoans such as Toxoplasma gondii. We also are investigating the activity of parasite molecules on host immune cells (dendritic, macrophages and T cells) and the mechanism by which they may alter their function. These molecules have potential in the therapeutic treatment of inflammatory diseases of humans (e.g. rheumatic diseases, IBD, Crone’s Disease).
The techniques that are used in my laboratory can be divided under several headings including -
- Molecular Biology - gene discovery and isolation, cloning and characterisation, general bioinformatics, recombinant expression of cDNAs in prokaryotic (E. coli) yeast (Saccharomyces cerevisiae and Pichia pastoris) and eukaryotic (insect cells) expression systems, optimisation of fermentation processes.
- Biochemistry - purification of native and recombinant proteins by conventional chromatographic techniques, protein analysis and proteomics, enzyme substrate and inhibitor analysis.
- Immunology - routine ELISA, cell isolation, proliferation assay, signal transduction, and cytokine measurement and analysis by ELISA, FACs analysis and RT-PCR/Real-time RT-PCR. Proteomics/Bioinformatics - We have employed the Applied Biosciences QSTAR® Elite System, (LC/MS/MS using the Tempo™ nano LC system, allowing separation of molecules along LC gradients as fast as 1 minute, with the added ability for de novo or “on the fly” sequencing of peptides) at our Faculties’ Center for Proteomics Technology to characterize pathogen secreted proteins that influence host immune responses. New ProteinPilot™ Software combines two state-of-the-art algorithms to perform thorough, reliable, protein identification including post transitional modifications of proteins.
- General expertise - The general area of expertise is in molecular biology, enzymology, immunodiagnostics, immunology, vaccinology in small and large animals, biochemistry, culturing of protozoan and helminth parasites, and basic cell biology.
Recent Publications
Poreba M, McGowan S, Skinner-Adams TS, Trenholme KR, Gardiner DL, Whisstock JC, To J, Salvesen GS, Dalton JP, Drag M.
Fingerprinting the Substrate Specificity of M1 and M17 Aminopeptidases of Human Malaria, Plasmodium falciparum. PLoS One. 2012;7(2):e31938. Epub 2012 Feb 16.
Dalton JP, Demanga CG, Reiling SJ, Wunderlich J, Eng JW, Rohrbach P.
Large-scale growth of the Plasmodium falciparum malaria parasite in a wave bioreactor. Int J Parasitol. 2012 Feb 8. [Epub ahead of print]
Jones PM, Robinson MW, Dalton JP, George AM.
The Plasmodium falciparum malaria M1 alanyl aminopeptidase (PfA-M1): insights of catalytic mechanism and function from MD simulations. PLoS One. 2011;6(12):e28589. Epub 2011 Dec 21.
McVeigh P, Maule AG, Dalton JP, Robinson MW.
Fasciola hepatica virulence-associated cysteine peptidases: a systems biology perspective. Microbes Infect. 2011 Dec 2. [Epub ahead of print]
Donnelly S, Dalton JP, Robinson MW.
How pathogen-derived cysteine proteases modulate host immune responses. Adv Exp Med Biol. 2011;712:192-207. Review.
Stack C, Dalton JP, Robinson MW.
The phylogeny, structure and function of trematode cysteine proteases, with particular emphasis on the Fasciola hepatica cathepsin L family. Adv Exp Med Biol. 2011;712:116-35. Review.
Robinson MW, Donnelly S, Hutchinson AT, To J, Taylor NL, Norton RS, Perugini MA, Dalton JP.
A family of helminth molecules that modulate innate cell responses via molecular mimicry of host antimicrobial peptides. PLoS Pathog. 2011 May;7(5):e1002042. Epub 2011 May 12.
Robinson MW, Corvo I, Jones PM, George AM, Padula MP, To J, Cancela M, Rinaldi G, Tort JF, Roche L, Dalton JP.
Collagenolytic activities of the major secreted cathepsin L peptidases involved in the virulence of the helminth pathogen, Fasciola hepatica. PLoS Negl Trop Dis. 2011 Apr 5;5(4):e1012.