Dr Daniel Humphreys
UKRI Future Leaders Research Fellow
Room: C08 Florey building
My research focusses on the host cell biology underlying infectious diseases with the aim of discovering new ways to combat globally important bacterial pathogens. I am a UKRI Future Leaders Research Fellow studying DNA damage responses and senescence in typhoid fever and its transmission by chronic bacterial carriage. I obtained my PhD and gained postdoctoral training at the University of Cambridge before being appointed as a lecturer in 2016 at the Department of Biomedical Science, University of Sheffield, where I received an MRC New Investigator Research Grant. Before that I studied Microbiology at the University of Liverpool (BSc) and Biological Sciences at the University of Manchester (Masters).
Awards and funding
I am undergraduate module co-ordinator for Pathobiology BMS106/BMS109 in which I teach infection and immunity. I also lecture on the MSc for Molecular Medicine and the MSc for Antimicrobial Resistance.
S.Typhi is transmitted via the faecal-oral route (yellow in Figure), a problem which is exacerbated in impoverished countries that lack access to clean water and good sanitation. Following ingestion, S.Typhi infects cells of the intestine before establishing a systemic, often fatal, infection underlying typhoid fever (pink in Figure).
Our research also investigates how S.Typhi and its typhoid toxin cause chronic infections in humans - ‘chronic carriage’ (turquoise in Figure). S.Typhi establishes chronic carriage by evading immune responses and causing an asymptomatic infection (yellow arrow), or following typhoid fever in 5% of cases (pink arrow). Chronic carriers transmit the pathogen in the population and are difficult to diagnose due to the lack of obvious clinical symptoms. The most infamous ‘chronic carrier’ was a household cook called Typhoid Mary (see figure) who caused numerous outbreaks of typhoid between 1900 - 1906. Chronic carriage is a stealth strategy of S.Typhi that continues today and helps perpetuate the infection cycle (turquoise arrow), which impedes global efforts to eradicate typhoid. By studying decisive disease mechanisms, our research contributes to global efforts combatting multidrug-resistant typhoid with the aim of improving the health and wealth of vulnerable communities in low- and middle-income countries.
Research projects on typhoid and chronic infection
Pathogenic bacteria manipulate the host DNA damage response (DDR) to execute virulence strategies and establish infections. This is exemplified by Salmonella Typhi that causes typhoid fever and fuels the infection cycle by chronic bacterial carriage. Upon infection, S.Typhi deploys the typhoid toxin, which is endocytosed by target host cells where the toxin activates the DDR. How the toxin hijacks the DDR and how this contributes to typhoid and chronic carriage is unclear. Understanding the toxin is especially important as related toxins are encoded by diverse bacterial pathogens that cause disease in humans and food-chain animals worldwide.
DNA damage responses underlying typhoid and chronic Salmonella carriage
We discovered a novel disease mechanism revealing that the typhoid toxin hijacks the activities of Replication Protein A (RPA), a key component of the DNA replication fork, which elicits DNA damage and cellular senescence.
Normally, RPA coats and protects single-stranded DNA (ssDNA) generated at DNA replication forks, thus acting as a cellular safeguard against DNA damage and permitting cell cycle progression (diagram in turquoise box). Remarkably, we found that the typhoid toxin hijacks this RPA mechanism to induce DNA replication stress and senescence (pink box). By inducing ssDNA breaks, toxin nuclease activity sequesters RPA and exhausts the pool of free RPA needed for DNA replication.
This causes irreparable DNA damage observed as signature accumulation of the DNA damage marker γH2AX at the nuclear periphery - Response Induced by a bacterial Genotoxin (RING). We found that the novel RING phenotype marks replication catastrophe and cellular senescence. Investigating this novel virulence mechanism is providing new information on disease while revealing potential therapeutic targets. Read the paper: http://rdcu.be/bQrD3
Investigating how pathogens accelerate the ageing of human host cells
We are investigating the significance of pathogen subversion of cellular ageing in typhoid and chronic Salmonella carriage. Understanding how chronic infection develops, and identifying effective diagnostic, treatment and prevention strategies is vital to typhoid elimination efforts.
Infections are often harder to combat and recover from as we age, which is partly due to senescence, and the idea that bacterial pathogens target this phenomenon could be important to infection and contribute to age-related pathologies such as cancer. We find that the typhoid toxin of S.Typhi induces chronic DNA replication stress via the RING phenotype, which results in cellular senescence, thus accelerating cellular ageing (diagram in yellow box).
Interestingly, proteins are secreted from cells with the RING phenotype that induce senescence in neighbouring cells (transmissible senescence in figure). These senescent cells are rendered more susceptible to intracellular Salmonella infections (see yellow bacteria in grey cells). We are currently investigating the mechanisms of senescence in the host-pathogen interaction. Read more: http://rdcu.be/bQrD3
May 15, 2020
Congratulations to our PhD student Mohamed El Ghazaly who took first prize in the Biology Category of the online research poster competition organised by Scientistt
Thank you to Scientistt for creating an animation summarising our research:
February 1, 2020
A big welcome to our new PhD student Nadia Baseer and our new post-doc Zhou Zhu!
October 1, 2019
A big welcome to our new PhD student Salma Srour!
September 26, 2019
Daniel Humphreys awarded UKRI Future Leaders Fellowship
September 19, 2019
Typhoid Fever: an age-old problem
September 9, 2019
Thanks to Take on Typhoid for highlighting our research.
September 7, 2019
Typhoid toxin accelerates cell ageing to enhance killer infection, study reveals
September 6, 2019
Typhoid toxin exhausts the RPA response to DNA replication stress driving senescence and Salmonella infection
July 31, 2019
Daniel Humphreys and collaborators awarded HIC-Vac Research Grant
May 18, 2019
Dr. Angela Ibler - Congratulations on receiving your PhD at the University of Cambridge!
PhD Project Opportunity
Enquires for postdoc, fellowship and PhD positions are welcome.
We advertise PhD opportunities (Funded or Self-Funded) on FindAPhD.com
For further information and details of other projects on offer, please see the department PhD Opportunities page:
- Typhoid toxin exhausts the RPA response to DNA replication stress driving senescence and Salmonella infection. Nature Communications, 10(1). View this article in WRRO
- MYO6 is targeted by Salmonella virulence effectors to trigger PI3-kinase signaling and pathogen invasion into host cells. Proceedings of the National Academy of Sciences, 114(15), 3915-3920. View this article in WRRO
- Inhibition of WAVE Regulatory Complex Activation by a Bacterial Virulence Effector Counteracts Pathogen Phagocytosis. Cell Reports, 17(3), 697-707. View this article in WRRO
- Arf6 coordinates actin assembly through the WAVE complex, a mechanism usurped by Salmonella to invade host cells. Proceedings of the National Academy of Sciences, 110(42), 16880-16885.
- Salmonella Virulence Effector SopE and Host GEF ARNO Cooperate to Recruit and Activate WAVE to Trigger Bacterial Invasion. Cell Host & Microbe, 11(2), 129-139.
- The Drosophila Arf1 homologue Arf79F is essential for lamellipodium formation. Journal of Cell Science, 125(23), 5630-5635.
- The Salmonella Effector SptP Dephosphorylates Host AAA+ ATPase VCP to Promote Development of its Intracellular Replicative Niche. Cell Host & Microbe, 5(3), 225-233.