Anouk Willemsen

Most viruses rely on the host to provide the entire translation machinery. However, giant viruses have evolved to encode part of the machinery themselves. Latest discovery: mimivirus (APMV) encodes its own initiation factor (vIF4F) and specifically promotes translation of viral mRNA!

We had a special speaker today at @i2sysbio.es , Anouk Willemsen @willemsenanouk.bsky.social. I have known her since my PhD and I truly admire her work on giant viruses
#viruses #microsky

For some reason, this didn't show up automatically in #giantVirus

Single-cell genomics reveals complex microbial and viral associations in ciliates and testate amoebae

"The frequent co-occurrence of giant viruses and microbial symbionts, especially in amoebae, suggests multipartite interactions"

On our way to the 6th Ringberg Symposium on Giant Virus Biology #ringbergGV2025

We also had bioinformatic exercises going from sequence download to tree building, inference of spillover events and recombination. Shout-out to @amanzanom.bsky.social , @dominikluecking.bsky.social & Büşra for leading this hands-on part. Definitely looking forward to the next edition! 2/2

Last week we wrapped up the first edition of the Virus evolution and ecology course under the umbrella of the brand new Master in Microbiome Science offered @univie.ac.at. We learned about viruses, their evolution, and their ecological impact across different ecosystems. 1/2

#VirEvol

Virus taxonomy: the database of the International Committee on Taxonomy of Viruses Abstract. Taxonomic classification underlies all biological science and is the basis for comparative analysis of biological organisms and therefore our und

#microsky #phagesky #phage #virus

academic.oup.com/nar/advance-...

Strain-level diversity of giant viruses infecting chlorarachniophyte algae in the subtropical North Pacific Giant DNA viruses are ubiquitous among unicellular eukaryotes and occur in marine, freshwater, and terrestrial environments. Despite intense metagenomic data mining, their strain-level diversity remai...

Strain-level diversity of #giantViruses infecting #chlorarachniophyte #algae in the subtropical North Pacific

by @fischerlab.bsky.social

doi.org/10.1101/2025...

Is it a flagellate? A tiny ball with tentacles? Contamination in my ciliate culture? NEW SUPERGROUP OF EUKARYOTES? Yes to all 4! Meet Solarion - just out in #Nature doi.org/10.1038/s415... Huge congrats to Marek Valt, Cepicka Lab & the star team! Very happy to be part of this project. #ProtistsOnSky

Reposting for #VirEvol

Proud moment to see the first Master student of the team (Lotte Mayer) successfully defend her Master's thesis work digging into viral factories of #giantViruses.

A link to part of her work:
doi.org/10.1101/2025...

@erc.europa.eu @univie.ac.at @cemess.bsky.social @dome-vienna.bsky.social

Last week #ESEB2025 wrapped up. It was a great opportunity to chat with colleagues, hear about great evolutionary research, present the group's work, and be a proud PI of Laura, who did a great job presenting her PhD work! Two years to go until next ESEB!

@eseb2025.bsky.social

Melbournevirus encodes a shorter H2B-H2A doublet histone variant that forms structurally distinct nucleosome structures Nature Communications - Melbournevirus encodes a conserved shorter H2B-H2A doublet variant. Here the authors report a cryo-EM structure of a nucleosome-like particle reconstituted with viral H4-H3...

our paper is online! rdcu.be/exXBX . Who would have thought that some #giantviruses not only have #histones, but even histone variants that make weird #nucleosomes (pdb 9CVT). Fantastic work from Ale Villalta and Chelsea Toner, with Hugo Bisio @molbiolgv.bsky.social and Chantal Abergel

Multiple origins, one function: evolutionary pathways of HSP70 proteins in viruses Heat shock proteins 70 (HSP70) are highly conserved molecular chaperones found across all domains of life, where they play essential roles in cellular stress responses. While HSP70 homologs have been ...

Heat Shock Protein 70 (AKA HSP70) in Mimiviridae and Phycodnaviridae likely originated from horizontal transfer from their protist hosts. By @sfelena.bsky.social & @amaachi.bsky.social

doi.org/10.1101/2025...

#giantVirus #VirEvol

Out now in its final peer-reviewed form @asm.org's Journal of Virology!

doi.org/10.1128/jvi....

@dome-vienna.bsky.social @erc.europa.eu @amersocvirology.bsky.social

Thanks for the comment! Originally we did write BONCAT in our manuscript. With your comment as support we might still be able to change it back in the final version.

When transported outside of the viral factory, the translation of viral mRNA takes place in a well-defined ring surrounding it. We expect these methods to be widely applicable to other viruses for the visualisation and quantification of RNA molecules.

4/4

While viral mRNA localisation changes depending on the infection stage, transcription occurs at well-defined spots within the viral factory. The original viral cores released within the cytoplasm most likely define these spots.

3/4

Combined with other labelling techniques, we show the #Mimivirus transcription and translation sites during an infection cycle in the amoeba host cell.

2/4

New work out!

Spearheaded by Lotte, we have developed a single-molecule messenger RNA fluorescence in situ hybridisation (smFISH) protocol for #giantViruses in an #Acanthamoeba host.

doi.org/10.1101/2025...

1/4

#ProtistsOnSky #MicroSky @dome-vienna.bsky.social @cemess.bsky.social @erc.europa.eu

by now you probably know that #giantviruses have #histones, but some also have histone variants! Check out our latest preprint on an essential H2B-H2A histone variant in Melbournevirus - a fantastic collaboration with the Abergel Lab, spearheaded by Ale Villalta. www.biorxiv.org/content/10.1...

Pacmanvirus isolated from the Lost City hydrothermal field extends the concept of transpoviron beyond the family Mimiviridae academic.oup.com/ismej/advanc... #jcampubs

Post-Doc Protist Viruses

Looking for a postdoc in environmental virology? Fascinated by giant viruses and their glycobiology?
We have a position available at the MPI for Marine Microbiology!
@mpimarinemicrobio.bsky.social @maxplanck.de
career.mpi-bremen.de/jobposting/8...

Don't forget the #giantVirus tag! With it, it will get collected in the Giant virus feed

🖐️

also @rubengonzalez.bsky.social @sfelena.bsky.social

🖐️

Reposting for #VirEvol and #giantViruses

Genomic and structural insights into Jyvaskylavirus, the first giant virus isolated from Finland Giant viruses of protists are a diverse and likely ubiquitous group of organisms. Here, we describe Jyvaskylavirus, the first giant virus isolated from Finland. This clade B marseillevirus was found i...

there is a new #giantvirus in town! and it speaks Finnish! www.biorxiv.org/content/10.1...

behold our paper on Medusavirus nucleosomes. Fantastic work by Chelsea Toner, @nhoitsma.bsky.social, and Sashi Weerawarana This giant virus also encodes a linker histone, more about that in the paper 🧪👩‍🔬 🧵.
www.nature.com/articles/s41...