Exploring the role of membrane proteins and adhesins in the infective life cycle of tick-borne Anaplasma

Background: Tick-borne bacterial diseases pose a significant threat to human and animal health and to livestock industries, particularly in low and middle-income countries. Anaplasma, a genus of tick-borne bacteria that cause the disease anaplasmosis, are exquisitely equipped to modulate and escape both innate immunity and adaptive immunity. Crucial to this ability are proteins on the bacterial cell surface which enable these pathogens to target and invade specific host cells. Remarkably, through a process known as antigenic variation, Anaplasma is able to constantly remodel its outer membrane proteins, enabling it to hide from adaptive immunity and hampering efforts to design vaccines against this important livestock pathogen.

The molecular details of how Anaplasma regulates antigenic variation are unknown, as are the specific molecular functions of most of its outer membrane proteins.

In this project you will use multi-disciplinary approaches, underpinned by molecular microbiology and protein biochemistry, to uncover the functions of Anaplasma surface proteins. You will use molecular biology and protein biochemistry to determine the molecular basis by which they recognise and are selective towards specific eukaryotic host cell structures. Using transcriptomics and proteomics, you will also investigate the regulatory mechanisms that control antigenic variation, paving the way to future sub-unit vaccine design.

Aims and objectives: We hypothesize that chemical cues stimulate antigenic variation by Anaplasma, that Anaplasma surface proteins are essential for infection of host cells, and can be targeted to generate anti-infectives.

Your main aims are:

i) Purify recombinant Anaplasma surface proteins and identify their host cell targets (using immunoprecipitations and protein biochemistry).

ii) Understand the structural basis for their ability to bind host cells (using protein crystallography and allied techniques)

iii) Determine how antigenic variation alters in response to chemical cues (using ‘omics)

Methods: This multi-disciplinary project offers you the opportunity to explore your scientific curiosity, supported by our commitment to your career development. Key methodologies encompass molecular biology, biochemistry, infection biology, microscopy, bioinformatics, and protein structure-function analyses.

Molecular techniques (such as cloning, site-directed mutagenesis, and Western blotting) and protein biochemistry (recombinant protein production, purification, and characterisation) will be central to your investigations. You will also receive training in cultivating tick-borne pathogens (Anaplasma and Ehrlichia), a fundamental aspect of this research. We will generate polyclonal antibodies and utilise them for affinity capturing of virulence factors in complex with their host targets within infected cell material and for fluorescence microscopy.

Structural elucidation methods, particularly x-ray crystallography, will help define protein:protein complexes and complementary techniques like isothermal calorimetry and gel filtration will provide further insights into interactions.

For examples of the techniques employed, please refer to references 2-4 below (note that these references relate to studies involving different bacteria).

In addition, we prioritise teamwork and encourage collaboration with local, national, and international partners. We are fully committed to supporting your development, facilitating travel, and fostering collaboration opportunities, to ensure you achieve your career goals.

Key references:

1) Salje, J. (2021) Cells within cells: Rickettsiales and the obligate intracellular bacterial lifestyle. Nature Reviews Microbiology 19: 375–390.

2) Lambert, C., Cadby, I.T., et al. (2015) Ankyrin-mediated self-protection during cell invasion by the bacterial predator Bdellovibrio bacteriovorus. Nature Communications 6(1): 8884.

3) Cadby, I.T., et al. (2019) Nucleotide signalling pathway convergence in a cAMP-sensing bacterial c-di-GMP phosphodiesterase. The EMBO Journal 38(17):e100772.

4) Meek, R.W., Cadby, I.T., Moynihan, P.J. and Lovering, A.L. (2019) Structural Basis for Activation of a Bdellovibrio Diguanylate Cyclase that Licenses Entry into the Predatory Lifecycle. Nature Communications 10(1):4086.

Supervisors: Dr Ian Cadby, Dr Jamie Mann, Dr Katja Klein

How to apply:

Please visit the Bristol Veterinary School website Funded 4-year PhD Scholarship nearmejobs.eu Bristol Veterinary School nearmejobs.eu University of Bristol for details of how to apply and the information you must include in your application – please read the Detailed Application Guidance section from the website for more information about this. If your application is shortlisted, you will be invited to interview on or before 17^th January. Interviews will take place on Microsoft Teams on 29^th January. Start date Sept 2025.

Candidate requirements: Standard University of Bristol eligibility rules apply. Please visit PhD Veterinary Sciences nearmejobs.eu Study at Bristol nearmejobs.eu University of Bristol for more information.

Contacts: please contact [email protected] with any queries about your application. Please contact the project supervisor for project-related queries: [email protected]