MRes Infectious & Tropical Diseases - Pathogen-host Cell Interactions

ID	Title	Overview
PB15	Complement evasion in Klebsiella pneumoniae: the role of Factor H (London)	Klebsiella pneumoniae (Kp), a commensal bacterium, can cause severe infections like pneumonia, sepsis, and urinary tract infections. Its polysaccharide capsule helps resist complement-mediated serum killing, a key immune defense. However, whether Kp exploits additional complement evasion strategies, such as targeting factor H – the primary soluble negative regulator of the alternative complement pathway – has not yet been clearly described. Understanding this potential interaction is essential to better define mechanisms of immune escape. During this project you will address this gap by assessing whether Kp binds factor H, using a combination of flow cytometry, serum resistance assays, and western blot analysis to detect and characterise this binding. Taking advantage of a collection of bacterial mutants will allow you to determine which surface molecules are responsible for factor H recruitment and whether this interaction contributes functionally to enhanced serum resistance. Other negative regulators of complement deposition can be similarly analysed as mechanisms of Kp resistance to complement-mediated killing.
PB16	Investigation of cell-autonomous immune responses to pathogenic bacteria (London)	The confluence of several factors (antimicrobial resistance, human migration, climate change) predict that we will continue to be infected and affected by emerging and re-emerging infectious diseases. When new infections occur, the first line of defence is the ability of single cells to confront and combat the pathogen, a process called cell-autonomous immunity. We discovered that septins, cytoskeletal proteins with well‐characterised roles in cell division, form cage‐like structures around Shigella for cell-autonomous immunity. However, the processes underlying septin cage entrapment, and the breadth of roles for septins in bacterial infection control, remain to be established. You will use pathogenic bacteria, including Shigella, to gain fundamental insights into septin roles during infection. You will discover new roles for the septin cytoskeleton in host defence against bacterial infection and investigate the role of septin-mediated immunity in vivo using zebrafish infection models.
PB17	Modulating antibody production through adaptation of secretory cargo machinery (London)	Antibodies are exclusively produced by B lymphocytes which, once activated, must morph into antibody factories termed plasma cells through progressive cellular and structural changes. Secretory machinery required to process, sort and transport the antibody cargo is upregulated, and the membranes required for export undergo massive proliferation. The central components of this pathway are specialised to adapt to cargo load, and specific molecular combinations have been found to tailor this pathway. Sar1 GTPase regulates the first step of secretory traffic. Sar1b is specifically upregulated during the conversion of B cells to plasma cells, which is unusual as this Sar1 paralogue is rarely expressed. You will knockdown Sar1b using CRISPR/Cas9 technology to investigate the effect on antibody secretion. Starting with cell lines to confirm the knockdown capability, then moving to primary B cells to investigate the longitudinal effect both on differentiation and antibody secretion.

Title

Overview

PB15

Complement evasion in Klebsiella pneumoniae: the role of Factor H

(London)

Klebsiella pneumoniae (Kp), a commensal bacterium, can cause severe infections like pneumonia, sepsis, and urinary tract infections. Its polysaccharide capsule helps resist complement-mediated serum killing, a key immune defense. However, whether Kp exploits additional complement evasion strategies, such as targeting factor H – the primary soluble negative regulator of the alternative complement pathway – has not yet been clearly described. Understanding this potential interaction is essential to better define mechanisms of immune escape.

During this project you will address this gap by assessing whether Kp binds factor H, using a combination of flow cytometry, serum resistance assays, and western blot analysis to detect and characterise this binding. Taking advantage of a collection of bacterial mutants will allow you to determine which surface molecules are responsible for factor H recruitment and whether this interaction contributes functionally to enhanced serum resistance. Other negative regulators of complement deposition can be similarly analysed as mechanisms of Kp resistance to complement-mediated killing.

PB16

Investigation of cell-autonomous immune responses to pathogenic bacteria

(London)

The confluence of several factors (antimicrobial resistance, human migration, climate change) predict that we will continue to be infected and affected by emerging and re-emerging infectious diseases. When new infections occur, the first line of defence is the ability of single cells to confront and combat the pathogen, a process called cell-autonomous immunity. We discovered that septins, cytoskeletal proteins with well‐characterised roles in cell division, form cage‐like structures around Shigella for cell-autonomous immunity. However, the processes underlying septin cage entrapment, and the breadth of roles for septins in bacterial infection control, remain to be established.

You will use pathogenic bacteria, including Shigella, to gain fundamental insights into septin roles during infection. You will discover new roles for the septin cytoskeleton in host defence against bacterial infection and investigate the role of septin-mediated immunity in vivo using zebrafish infection models.

PB17

Modulating antibody production through adaptation of secretory cargo machinery

(London)

Antibodies are exclusively produced by B lymphocytes which, once activated, must morph into antibody factories termed plasma cells through progressive cellular and structural changes. Secretory machinery required to process, sort and transport the antibody cargo is upregulated, and the membranes required for export undergo massive proliferation. The central components of this pathway are specialised to adapt to cargo load, and specific molecular combinations have been found to tailor this pathway.

Sar1 GTPase regulates the first step of secretory traffic. Sar1b is specifically upregulated during the conversion of B cells to plasma cells, which is unusual as this Sar1 paralogue is rarely expressed. You will knockdown Sar1b using CRISPR/Cas9 technology to investigate the effect on antibody secretion. Starting with cell lines to confirm the knockdown capability, then moving to primary B cells to investigate the longitudinal effect both on differentiation and antibody secretion.