https://t.co/yo0ADqaJHP Thrilled to share our new study! We show that mirusviruses include lineages packed with spliceosomal introns and likely replicating in the nucleus of unicellular eukaryotes—a sharp contrast to most large eukaryotic viruses that replicate in the cytoplasm.

7/7 The characterization of this vast repertoire of viruses paves the way toward a better understanding of their role in regulating methanogen communities globally as well as the development of much-needed genetic tools. Stay tuned for further developments!

6/7 Methanogens are widespread in the human gut. Are there any signatures of viral adaptation to the gut environment? Yes! We found an enrichment of Ig-like domains and Diversity Generating Retroelements (DGRs) in gut viruses, which can help virions attach to the mucosal layer.

5/7 The largest group of head-tailed viruses infect Methanobacteriales – archaea which harbor a pseudomurein cell wall. We found a large variety of lysins used to enter and egress through the archaeal cell wall, a striking example of convergent evolution with bacteriophages.

4/7 We describe 87 family-level groups, half of them containing a single viral genome. This indicates that there is a large hidden diversity of viruses that remains to be characterized. One of the groups contains not-autonomous viruses (first archaeal cf-PICI elements).

3/7 Using a comprehensive database of 156,000 CRISPR spacers, we identified 282 high-quality (pro)viruses covering all major lineages of methanogens. For many lineages (Methanoliparales, Methanomassiliicoccales, Methanofastidiosales) these are the first ever reported viruses.

2/7 Archaea are major producers of methane, a major greenhouse gas, and inhabit diverse environments, including the human gut. But what are the viruses that infect methanogens?

1/7 What happens when specialists of methanogens join forces with experts in archaeal viruses? Happy to share my last study with @SGribaldo, @mkrupovic, guillaumeborrel, @institutpasteur funded by @ANR. Link: https://t.co/z2HfH9SXvs Thread below