Research Opportunities

Apicomplexan pathogens are highly-adapted intracellular parasites of humans causing disease including malaria, toxoplasmosis and cryptosporidiosis. These parasites actively confront, subvert and defend themselves against host immune attack using a complex suite of parasite surface and secreted proteins that hijack immune signalling pathways. Moreover, transmission and generation of genetic novelty occurs in definitive hosts where differentiation into sexual parasite forms occurs. Relatively little is known, however, of the molecules and processes that drive these events, particularly during the sexual stages of parasite development. This project will use new methods in in vitro culture of sexual development in Toxoplasma, advanced methods for global spatial characterisation of parasite cell proteomes in order to identify specific proteins thought to be implicated in these interactions, and then utilise CRISPR/cas9 mutagenesis tools to engineer pools of strains deficient in these specific proteins. By assaying mutant pools both in vitro, and through the definitive host we will identify proteins and processes required for sexual stage conversion.

Bacterial chemotaxis response is crucial for colonization and infection, and the signal transduction systems that mediate such responses are potential new targets for antimicrobial drug development. Such system has emerged as a paradigm for understanding the principles of intracellular signal transduction both in bacterial and eukaryotic cells. In bacterial cells, hundreds of basic core signalling units consisting of three essential components, the chemoreceptors, the histidine kinase and the adaptor protein, assemble into a two-dimensional lattice array which allows cells to amplify and integrate many varied and possibly conflicting signals to locate optimal growing conditions. We aim to determine the structure and dynamics of the chemotaxis signalling arrays using state-of-the-art cryo-electron microscopy and tomography. We will take both in vitro and in situ structural approaches and combined with large-scale all atom molecular dynamic simulations. The ultimate goal is to assemble a time-resolved molecular movie of the entire signalling pathway in bacterial chemotaxis at an atomic level. 

The Higgins laboratory are expert in the structural studies of host-parasite interactions in parasitic diseases such as malaria. They study how interactions at the heart of processes such as erythrocyte invasion are mediated. They explore how parasite surface proteins manipulate the human immune system. They examine antibodies produced in response to human vaccination and determine how these function, and they use this information to design improved vaccine components.

To discuss possible projects, contact: matthew.higgins@bioch.ox.ac.uk

Inflammatory bowel disease (IBD) encompasses two major diseases Crohn’s disease and ulcerative colitis. A subgroup of patients develop extreme phenotypes of intestinal inflammation due to rare monogenic defects. This includes several forms of immunodeficiency with diverse functional pathogenic mechanisms. Those defects inform on the importance of antimicrobial activity, hyperinflammatory responses and immune regulation. We investigate children with very early onset of intestinal inflammation using whole genome or whole exome sequencing to discover novel high impact genes and analyse the involved signaling pathways in vitro, in situ and in vivo. We like to understand the pathogenesis of rare “orphan” diseases to develop better treatment options for those disorders and improve understanding of pathogenic mechanisms of IBD as a whole.

The project will focus on single cell proteomic and transcriptomic analysis of patients with monogenic forms of IBD in order to understand functional mechanisms of monogenic IBD, to understand cellular communication and to identify novel therapeutic targets to induce cellular antimicrobial activity in order to maintain and reinstall intestinal mucosal barrier function.

Malaria is a major burden on global health with about 200 million cases worldwide, and 600,000 deaths per year. Inadequate diagnostics is a major barrier to effective management of cases and elimination of the disease. The current gold standard method for malaria diagnosis is light microscopy of blood films. About 170 million blood films are examined every year for malaria, which involves manually identifying and counting parasites. However, microscopic diagnostics are not standardized and depend heavily on the experience and skill of the microscopist, many of whom work in isolation, with no rigorous system in place for maintenance of their skills. For false negative cases this leads to incorrect diagnosis with unnecessary use of antibiotics, a second consultation, lost days of work, and in some cases progression into severe malaria. For false positive cases, this results in unnecessary use of antimalarial drugs and side effects.

To improve malaria diagnostics, the Lister Hill National Center for Biomedical Communications, an R&D division of the U.S. National Library of Medicine, NIH and Mahidol-Oxford Tropical Medicine Research Unit, University of Oxford, in Bangkok, Thailand are developing a fully automated low-cost system that uses a mobile phone and standard light microscope for parasite detection and counting on blood films. Compared to manual counting, automatic parasite counting is more reliable and standardized, reduces the workload of the malaria field workers and reduces diagnostic costs. To count parasites automatically, the system uses image processing methods to find cells infected with parasites in digitized images of blood films. The system is trained on manually annotated images and machine learning methods then discriminate between infected and uninfected cells, detect the type of parasites that are present, and perform the counting. The system uses a regular smartphone and digital images acquired on standard light microscopy equipment making it ideal for resource-poor settings.

This PhD project will develop and test this system for real-world use for malaria diagnosis. It will include optimisation of the system at NIH and testing of the system in the field at MORU including the smartphone application interface and performance, the system for connecting the smartphone to standard light microscopes, development of a core set of performance metrics for the application, field testing of the entire system for malaria diagnosis together with government healthcare workers and National Malaria Control Programme staff, structured interviews to gather feedback on the system and its potential role in malaria diagnosis in different settings, a formal field trial of the system performance and development of a system implementation guidance document for National Malaria Control Programmes.

The student will join a dynamic team of image analysis specialists at NLM and epidemiologists, modellers and clinicians at the MORU offices in Bangkok. They will spend time at field sites in malaria-endemic areas and will interact with government staff. Training will be provided at NIH on basic image analysis and smartphone application development and at MORU on malaria miscroscopy, clinical study methodology, data analysis and research ethics.

Leishmaniasis is an important disease caused by protozoan parasites that are transmitted by infected sand fly bites in tropical and subtropical regions.  Depending on the strain of Leishmania, disease forms in humans range from localized, self-limiting cutaneous lesions to visceralizing infections that are fatal in the absence of treatment.   The specific contribution of parasite genotype to disease outcome remains largely unknown. Taking advantage of a recently revealed sexual cycle that occurs during Leishmania development in the insect vector, our goal is to generate a series of hybrids between cutaneous and visceral strains that will be phenotyped in mouse models of cutaneous and visceral leishmaniasis.  Each hybrid will be subjected to whole genome DNA and RNA-sequencing to follow parental allele, structural variation, including chromosome somy, gene expression, and epigenetic differences that associate with disease outcome.  Experimental approaches will involve genetic manipulation of the parasite, DNA and RNAseq analysis, single cell genomics, and the application of various computational/bioinformatics methods developed to facilitate QTL and GWAS studies that identify linkage between genes and phenotypes. 

Malaria remains an important global health problem; with increasing drug resistance and the lack of an effective vaccine, new therapies are needed and should be based on a rigorous understanding of parasite biology. Our NIAID lab has used a multidisciplinary approach to discover and characterize the three known ion channels in bloodstream malaria parasites. Through academic and pharmaceutical collaborations, we have also found potent inhibitors that are being pursued as new antimalarial drugs. Research projects will be tailored to the interests of the trainee and expertise available in possible collaborator labs. These projects may utilize molecular biology including CRISPR and heterologous expression, structural biology including cryoEM, biochemical methods including electrophysiology, epigenetics, and high-throughput screening for drug discovery.  These and other methods are actively used in the lab. Dr. Desai has collaborators at Oxford, Cambridge, and Wellcome Sanger, depending on project.

Monoclonal antibodies have emerged in recent years as powerful tools to guide vaccine design and potentially to directly prevent infectious disease. Plasmodium falciparum, which causes malaria, is a relatively unexplored pathogen in this area, with only a few major vaccine candidates dominating the field despite the thousands of proteins expressed by the parasite. This project aims to isolate, characterize and determine the structures of human monoclonal antibodies against known and novel P. falciparum blood-stage antigens using cutting-edge technology. This collaborative project combines the expertise of the Tan lab in isolating human monoclonal antibodies against infectious pathogens and the expertise of the Higgins lab in solving crystal structures of antibody-antigen complexes to identify new sites of vulnerability on parasites at high resolution.

*This project is available for the 2021 Oxford-NIH Pilot Programme*