Josie Elliott

Josie Elliott

@josie-e.bsky.social

Postdoc studying evolutionary microbiology with phage and pseudomonas at MMSB Lyon, France with Anne Chevallereau in the MEEP group (She/Her)

783 followers606 following47 posts

Josie Elliott
@josie-e.bsky.social

Just finished my first @skypeascientist.bsky.social session and feeling so full of enthusiasm for science from the lovely questions the middle schoolers asked. However I did compare phage specificity to someone who makes chairs ending up in a coca-cola factory and not knowing how to make anything 🤦‍♀️

Josie Elliott reposted

Anne Chevallereau
@annechevallereau.bsky.social

🎉Extremely happy that Josie Elliott was awarded a MCSA postdoctoral fellowship to continue our work on the competition between mobile genetic elements in bacteria ! Congratulations !

Josie Elliott@josie-e.bsky.social

I'm excited and grateful to share that I have been awarded a Marie Skłodowska-Curie postdoc fellowship for my work with @annechevallereau.bsky.social at @mmsb-lyon.bsky.social. I feel incredibly lucky and I'm looking forward to getting to work on all the phage-y experiments we have planned 🧫

Josie Elliott reposted

Sean Meaden
@seanmeaden.bsky.social

Two fully-funded PhD openings in my research group at the University of York. If you’re excited about viromes, phage biology, Nanopore sequencing, soils and the odd bit of alpine or agricultural field sampling, we’d love to hear from you! 🌱🦠🏔️ tiny.cc/c4pv001 tiny.cc/e4pv001

tiny.ccA Farewell to Arms: The Trade-off Between Growth and Defence in Bacteria (York YBDTP Project) at University of York on FindAPhD.comPhD Project - A Farewell to Arms: The Trade-off Between Growth and Defence in Bacteria (York YBDTP Project) at University of York, listed on FindAPhD.com
Josie Elliott
@josie-e.bsky.social

This nutrient dependent efficacy of CRISPR-Cas interference on phage was a really cool finding and potentially opens up bigger questions about what we might be missing when we screen phage and defence systems in only optimal growth conditions.

Josie Elliott
@josie-e.bsky.social

Interestingly we found that CRISPR worked great against a variety of temperate and virulent phages across a range of infection metrics. However, a few phages were resistant to CRISPR, some which made sense (jumbo phage) and others not.

Josie Elliott
@josie-e.bsky.social

We ran all our initial tests in optimal high nutrient conditions. However, when we re-tested some of our CRISPR-impervious phage again in low nutrient conditions we found that two of these phages could no longer resist CRISPR defences, allowing the bacteria to grow unaffected by phage lysis!

Josie Elliott
@josie-e.bsky.social

Because I put restriction sites around all parts of the CRISPR-Cas genes, including the spacers, it made it simple to swap out the spacers with cheap primers before integrating the whole system back into the genome of P. aeruginosa, thus allowing us to target this system against any phage we wanted.

Josie Elliott
@josie-e.bsky.social

Once integrated into the P. aeruginosa genome the synthetic CRISPR-Cas system worked great against plasmids, so we turned our system against a panel of phage to see if, when given targeting spacers, we could find patterns as to what phages CRISPR does and doesn’t work against.

Josie Elliott
@josie-e.bsky.social

We were interested into diving deeper on understanding how useful CRISPR-Cas systems are to the bacteria that carry or acquire them. So at the start of my PhD I spent many hours creating a synthetic, minimal, modular version of the type IF CRISPR-Cas system of Pseudomonas aeruginosa.

Josie Elliott reposted

David Sünderhauf
@davvi36.bsky.social

PhD opportunity, please share: We are looking for a prospective PhD student to start in October 2026 who is excited about bacteria (Klebsiella pneumoniae), how they interact, and how they exchange DNA. All details can be found on the funder website 👉 gw4biomed.ac.uk/developing-c...

gw4biomed.ac.ukDeveloping CRISPR-Cas antimicrobials to tackle antibiotic resistance spread in Klebsiella pneumoniae - GW4 BioMed MRC DTPProject Code MRCIIAR26Ex van Houte Project Type Wet lab Research Theme Infection, Immunity, Antimicrobial Resistance and Repair Project Summary Download Summary Antimicrobial resistance (AMR) poses a ...

Josie Elliott reposted

lenabue.bsky.social
@lenabue.bsky.social

Honored to have our paper featured in the Spotlight of @cp-trendsmicrobiol.bsky.social by authors @josie-e.bsky.social & @annechevallereau.bsky.social Thank you for making our work more accessible and highlighting its relevance! www.cell.com/trends/microbiology/fulltext/S0966-842X%2825%2900158-1

cell.comFast phages outcompete by depleting host resourcesIn nature, phages frequently coinfect bacteria, leading to inter-species competition. Furthermore, phage therapy often involves using a cocktail of different species to circumvent bacterial resistance...

Josie Elliott reposted

Anne Chevallereau
@annechevallereau.bsky.social

✍️ We had a great time writing this Spotlight article on one of our favorite topics: how phages interact with each other! 🦠 From cooperation to competition, phage-phage interactions reveal a fascinating layer of microbial life that’s often overlooked. A piece crafted by the talented Josie Elliott!

lenabue.bsky.social@lenabue.bsky.social

Honored to have our paper featured in the Spotlight of @cp-trendsmicrobiol.bsky.social by authors @josie-e.bsky.social & @annechevallereau.bsky.social Thank you for making our work more accessible and highlighting its relevance! www.cell.com/trends/microbiology/fulltext/S0966-842X%2825%2900158-1

cell.comFast phages outcompete by depleting host resourcesIn nature, phages frequently coinfect bacteria, leading to inter-species competition. Furthermore, phage therapy often involves using a cocktail of different species to circumvent bacterial resistance...
Josie Elliott
@josie-e.bsky.social

Had a great time in Paris at the EMBO workshop on the immune system of bacteria, thank you to all the organisers. Conferences in cool cities are also the perfect opportunities to go to other awesome places like Fontainebleau and try some outdoor bouldering

Josie Elliott reposted

Alexander Harms
@aharms485.bsky.social

Fantastic new preprint of Vaughn Cooper's lab @vscooper.micropopbio.org - filamentous phages can get cancer and it's contagious. 🔥👇🏼 www.biorxiv.org/content/10.1...

biorxiv.orgFilamentous cheater phages drive bacterial and phage populations to lower fitnessMany bacteria carry phage genome(s) in their chromosome (i.e., prophage), and this intertwines the fitness of the bacterium and the phage. Most Pseudomonas aeruginosa strains carry filamentous phages ...
Josie Elliott
@josie-e.bsky.social

I could not be more grateful for having such lovely examiners in @jpjhall.bsky.social and @zaminiqbal.bsky.social and moreover the best lab group ever with the @taylorlabgroup.bsky.social . 4 years has fully converted me to a die hard phage lover 🦠🧬👩‍🔬

Tiffany Taylor@taylorlabgroup.bsky.social

Hooray 🎉 @josie-e.bsky.social who passed her PhD viva with flying colours. Many thanks to examiners @jpjhall.bsky.social & @zaminiqbal.bsky.social. Josie was cosupervised by Edze Westra & will soon start her postdoc with @annechevallereau.bsky.social Go get 'em Dr Elliott.

Josie Elliott
@josie-e.bsky.social

However, without imposing extra costs for mutating the phage receptor, and against a single, lytic phage, we see that something as simple as the difference in the frequencies of phage resistant cells can predict selection for a CRISPR-Cas system. 10/10

Josie Elliott
@josie-e.bsky.social

It's been a huge learning curve to take this paper from abstract discussion, through many revisions, to a real publication out in the world, and I can’t thank my colleagues – both those on this paper and many others not – enough for all the support and help during this process!

Josie Elliott
@josie-e.bsky.social

Over a short 24-hour experiment, the change in population frequency behaved as predicted by the mathematical model! The strains with a CRISPR-Cas system were selected for in the total population when f∆ was positive (>1) and not selected for when f∆ was negative (<1). 8/10

Josie Elliott
@josie-e.bsky.social

This paper is a nice piece of the puzzle to understand how cells that acquire CRISPR-Cas systems via horizontal gene transfer might be selected for in mixed populations, although of course real ecological situations will be a lot more complicated... 9/10

Josie Elliott
@josie-e.bsky.social

As it can be a tricky to tag & track 5 different phenotypes of cells that are identical apart from possession of CRISPR-Cas systems or mutations in their phage receptors, we inserted a very short nonsense region into each strain’s genome and targeted that with qPCR primers. 6/10

Josie Elliott
@josie-e.bsky.social

We followed the relative strain frequency with qPCR with initial set ups of either: a higher frequency of cells in the population with CRISPR-Cas had phage resistance (f∆ >1), or the population lacking CRISPR-Cas had the higher frequency of phage resistant cells (f∆<1). 7/10

Josie Elliott
@josie-e.bsky.social

We called the difference between the frequencies of the populations showing phage resistance f∆. This holds even if the population lacking CRISPR-Cas is larger the population with a CRISPR-Cas system... 4/10

Josie Elliott
@josie-e.bsky.social

(E.g. as you might find in a situation where a small subpopulation recently gained a CRISPR-Cas system via horizontal gene transfer). We also wanted to test this experimentally, so we used Pseudomonas aeruginosa and its obligately lytic phage DMS3vir as our model. 5/10

Josie Elliott
@josie-e.bsky.social

David & Sylvain built a deterministic mathematical model & found that when 2 populations of bacteria, one with, one without a CRISPR-Cas system meet, the difference in the frequencies of cells with phage defences in each population determines which population is selected for 2/10

Josie Elliott
@josie-e.bsky.social

E.g. if 30% of population with CRISPR-Cas has some kind of phage resistance (CRISPR-Cas immunity/phage receptor mutation) & the population lacking CRISPR-Cas has 15% phage resistance (phage receptor mutation) then the population with CRISPR-Cas will be selected for. 3/10

Josie Elliott
@josie-e.bsky.social

Thank you so much @meehubs.bsky.social and the Microbiology Society! I might be a little biased now, but I have had an amazing time at the Oxford Hub 😊

MEEhubs@meehubs.bsky.social

Congratulations to our MEEhubs2024 Oxford Poster Award winner @josie-e.bsky.social! 🎉🏆 Prize generously sponsored by the Microbiology Society UK

Josie Elliott reposted

Tiffany Taylor
@taylorlabgroup.bsky.social

From James Horton (not here). James and myself have recently penned ✍️ a review article for Microbiology titled Mutation Bias and Adaptation in Bacteria: www.microbiologyresearch.org/content/jour... A short 🧵 on why we should care about mutation bias below (1/7)

microbiologyresearch.orgMutation bias and adaptation in bacteriaGenetic mutation, which provides the raw material for evolutionary adaptation, is largely a stochastic force. However, there is ample evidence showing that mutations can also exhibit strong biases, wi...
Josie Elliott
@josie-e.bsky.social

I am of course biased but this is an amazing PhD opportunity and supervisory team. Come join us!

Tiffany Taylor@taylorlabgroup.bsky.social

The field of microbial defence systems is a crazy place to be right now! Competitive #PhD opportunity (SWBioDTP) with me at Life Sciences in Bath in collab with Edze Westra at Exeter ESI (Falmouth): Aiming to explore regulatory control of multiple defence systems. www.findaphd.com/phds/project...